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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934

Filed by the Registrant ý

Filed by a Party other than the Registrant o

Check the appropriate box:

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Preliminary Proxy Statement

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Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

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Definitive Proxy Statement

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Definitive Additional Materials

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Soliciting Material under §240.14a-12

 

Trinseo S.A.

(Name of Registrant as Specified In Its Charter)

 

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

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No fee required.

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Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.
    (1)   Title of each class of securities to which transaction applies:
        
 
    (2)   Aggregate number of securities to which transaction applies:
        
 
    (3)   Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):
        
 
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Fee paid previously with preliminary materials.

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Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

 

 

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Amount Previously Paid:
        
 
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GRAPHIC

Trinseo S.A.
Société anonyme
REGISTERED OFFICE:
26-28, rue Edward Steichen
L-2540 Luxembourg
Grand Duchy of Luxembourg
Luxembourg RCS: B 153.549
PRINCIPAL PLACE OF BUSINESS:
1000 Chesterbrook Boulevard, Suite 300
Berwyn, PA 19312 USA

April [    ], 2021

Dear Shareholder:

We cordially invite you to attend our 2021 annual general meeting of shareholders (the "General Meeting") on Monday, June 14, 2021 at 12:00 p.m. (local time), to consider the extraordinary and ordinary resolutions discussed in the attached proxy statement. Due to the COVID-19 pandemic and ongoing travel restrictions and health and safety concerns, the board of directors of Trinseo (the "Board") has decided to again hold the General Meeting via teleconference, without a physical meeting, in accordance with the Luxembourg law dated September 23, 2020 on measures on holding meetings of companies and other legal entities ("portant des mesures concernant la tenue de réunions dans les sociétés et dans les autres personnes morales") (as amended). Shareholders will not be able to attend the General Meeting in person. Further details regarding admission to the General Meeting, via teleconference, as well as the business to be conducted at the meeting is more fully described in the accompanying materials.

In addition to the typical proposals to be voted on at our General Meeting, our board of directors has unanimously approved, and is submitting to our shareholders for approval, several proposals related to a cross-border merger transaction that will, effectively, result in a change of our place of incorporation from Luxembourg to Ireland (see Proposal 1). The proposed transaction would result in you holding shares in an Irish public limited company (Trinseo PLC) rather than a Luxembourg Société anonyme (Trinseo S.A.). As discussed further in the proxy statement, we and the Board believe that Ireland provides the Company a favorable legal and regulatory infrastructure, providing flexibility while continuing to allow access to financial markets and customers, without impacting our business operations or our shareholders. If the proposal is passed, upon effectiveness of the merger, the number of shares you will own in Trinseo PLC will be the same as the number of shares you held in Trinseo S.A. immediately prior to the completion of the transaction.

After the completion of the merger, Trinseo will continue to conduct the same business operations as were conducted prior to the merger, but with Trinseo PLC as the parent company. We expect the ordinary shares of Trinseo PLC to be listed on the New York Stock Exchange under the symbol "TSE," the same symbol under which your shares in Trinseo S.A. are currently listed. After completion of the transaction, we will remain subject to the U.S. Securities and Exchange Commission reporting requirements and the applicable corporate governance rules of the New York Stock Exchange, and we will continue to report our financial results in U.S. dollars and under U.S. generally accepted accounting principles.

We are also asking our shareholders to approve several additional proposals related to the merger. Proposals 3 and 4 are advisory proposals where we are asking our shareholders to approve, on an advisory basis, the Trinseo PLC articles of association to be in effect at the time of the merger, and certain sections of the Trinseo PLC articles of association which would represent material changes to Trinseo S.A.'s current articles of association. Proposal 5 seeks approval of the creation of distributable profits of Trinseo PLC under Irish law by reducing the entire share premium created from the issuance and allotment of ordinary shares of Trinseo PLC pursuant to the merger (or such lesser amount as the Trinseo PLC Board may approve). If this proposal is not approved by shareholders, Trinseo PLC will not be able to pay dividends, make other distributions, or repurchase shares unless and until distributable profits are otherwise generated.

We are also asking our shareholders to approve an amendment to our current Luxembourg articles of association as amended and restated on June 20, 2018 (the "Articles"), to be effective prior to the merger, to increase the size of our Board to thirteen directors (Proposal 2), and to vote to elect the thirteenth director nominee, Victoria Brifo, a talented candidate the Board has unanimously voted to nominate for election at this meeting (see Proposal 7).

We describe in detail the cross-border merger and other actions we expect to take in the attached Notice of General Meeting of Shareholders and proxy statement. We encourage you to read this entire document carefully. You should carefully consider "Risk Factors" beginning on page 12 for a discussion of risks related to the merger before voting. We have also made available a copy of our Annual Report on Form 10-K for our fiscal year ended December 31, 2020. We encourage you to read the Form 10-K, which includes information on our operations and products, as well as our audited financial statements.


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The Board unanimously recommends that you vote to approve the merger and the other proposals described in the accompanying proxy statement.

As in previous years, we will be using the "Notice and Access" method of providing proxy materials to shareholders via the Internet. We believe that this process provides shareholders with a convenient and quick way to access the proxy materials and vote, while allowing us to conserve natural resources and reduce the costs of printing and distributing the proxy materials. We will mail to most of our shareholders a Notice of Internet Availability of Proxy Materials for the General Meeting containing instructions on how to access our proxy statement and Annual Report and vote electronically via the Internet. Each notice will also contain instructions on how to receive a paper copy of the proxy materials. All shareholders who do not receive a notice will receive a paper copy of the proxy materials by mail or an electronic copy of the proxy materials by email.

Your vote is important regardless of the number of shares you own. Whether or not you plan to attend the General Meeting, we encourage you to consider the matters presented in the proxy statement and vote as soon as possible. Instructions for Internet and telephone voting are included with the Notice of Internet Availability of Trinseo's Proxy Materials for the General Meeting. If you prefer, you can request to receive proxy materials by mail, including a proxy card, and vote by mail by completing and signing the proxy card and returning it in the envelope provided.

Sincerely yours,

GRAPHIC

Frank A. Bozich
President and Chief Executive Officer


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Trinseo S.A.

General Meeting of Shareholders

Luxembourg, Grand Duchy of Luxembourg

June 14, 2021
12:00 p.m. CEST
Via teleconference

Trinseo S.A.
Société anonyme
REGISTERED OFFICE:
26-28, rue Edward Steichen
L-2540 Luxembourg
Grand Duchy of Luxembourg
Luxembourg RCS: B 153.549

Principal executive offices of Trinseo S.A.
1000 Chesterbrook Boulevard, Suite 300
Berwyn, Pennsylvania 19312 USA
+1 610-240-3200

NOTICE OF GENERAL MEETING OF SHAREHOLDERS

To the Shareholders of Trinseo S.A.:

Notice is hereby given that an annual general meeting of shareholders (the "General Meeting") of Trinseo S.A. ("we," "Trinseo" or the "Company") will be held on Monday, June 14, 2021, at 12:00 p.m. Central European Summer Time, for the purposes described below and in further detail in the proxy statement accompanying this notice. Due to the COVID-19 pandemic and ongoing travel restrictions and health and safety concerns, the board of directors of Trinseo (the "Board") has decided to again hold the General Meeting via teleconference, without a physical meeting, in accordance with the Luxembourg law dated September 23, 2020 on measures on holding meetings of companies and other legal entities ("portant des mesures concernant la tenue de réunions dans les sociétés et dans les autres personnes morales") (as amended). Shareholders will not be able to attend the General Meeting in person. Only shareholders of record at the close of business on April 20, 2021 (the record date for the General Meeting) may attend. All shareholders must register to attend the General Meeting teleconference. Shareholders may register by going to the Company's voting website, www.proxyvote.com, entering their 16-digit control number found on their proxy card or in their General Meeting materials, and click on the box labeled "Register for Meeting." Shareholders who register to attend the General Meeting will be given dial-in information for the teleconference, and when dialing into the General Meeting will be asked to confirm their name and control number prior to admission into the teleconference.

If you are a shareholder of record, you may vote your shares during the General Meeting. Beneficial shareholders who held their shares through a broker, bank or other nominee on the record date for the General Meeting, who wish to vote their shares by proxy during the General Meeting must register in advance. To register, beneficial holders must first obtain a legal proxy, executed in their favor, from their broker, bank or other nominee. Proof of such legal proxy (e.g., a forwarded email from the beneficial holder's broker, bank or other nominee with the legal proxy attached, or an image of the legal proxy attached to the email) must be sent via email to F21MTGS@trinseo.com and labeled "Legal Proxy" in the subject line. Requests to vote at the General Meeting must be received no later than 6:00p.m. CEST, on Monday, June 7, 2021. Beneficial holders will receive a confirmation of registration by email and may vote at the General Meeting.

The General Meeting is being held for the purpose of approving two extraordinary resolutions, which require approval from two-thirds (2/3) of the votes cast in person or by proxy at the General Meeting. Approval of these extraordinary resolutions are required to be reviewed by a Luxembourg notary. The General Meeting is also being held for the purpose of approving thirteen ordinary resolutions, which require either approval of a majority of the shares represented in person or by proxy at the General Meeting, or require advisory approval by shareholders.

First, for the purpose of approving extraordinary resolutions in order:

1.
After review of the reports required by Luxembourg law, to approve the proposed merger of the Company into Trinseo PLC, a public limited company incorporated under the laws of Ireland with company number 562693 and having its registered office at Riverside One, Sir John Rogerson's Quay, Dublin 2, D02 X576 (the "Merger"), in accordance with the common draft terms of merger dated April [    ·    ] 2021 (the "Common Draft Terms") whereby Trinseo PLC will acquire all assets and liabilities of the Company by universal succession of title, and the Company will cease to exist (the "Merger Proposal");

2.
To approve an amendment to Article 7.1.1 of the Company's articles of association as amended and restated on June 20, 2018 (the "Articles") to increase the size of the Company's Board to a maximum of thirteen (13) directors (the "Board Increase Proposal").

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Second, for the purpose of approving ordinary resolutions in order:

3.
Subject to approval of the Merger Proposal, to consider and approve, on a non-binding advisory basis, the proposed Memorandum and Articles of Association of Trinseo PLC (the "Proposed Constitution"), which are attached to this proxy statement as Annex B, which will be in effect at time of the Merger and which will effectively replace our Articles (the "Irish Constitution Proposal");

4.
Subject to approval of the Merger Proposal, to consider and vote upon separate proposals to approve, on a non-binding advisory basis, the following material differences between our Articles and the Proposed Constitution which are being presented in accordance with the requirements of the Securities and Exchange Commission (the "SEC") as three separate advisory proposals (we refer to such proposals as the "Advisory Constitution Proposals"):

a.
Upon the effective date of the Merger, under the Proposed Constitution, Trinseo PLC will have a share capital of (i) 4,000,000,000 ordinary shares, par value $0.01 per share, (ii) 1,000,000,000 preferred shares, par value $0.01 per share and (iii) 25,000 deferred ordinary shares par value €1.00 per share, in comparison to the Articles which provides for a share capital of up to 50,000,000,000 shares, par value $0.01 per share;

b.
Under the Proposed Constitution, the board of directors of Trinseo PLC will have discretion to issue up to the authorized but unissued amount of Trinseo PLC's share capital for cash without preemptive rights for a period of five years from adoption, in comparison to the Articles which permit the Board to issue up to 20% of the existing share capital without offering those shares to existing shareholders and up to 100% of the existing share capital with preemptive rights, until 2023.

c.
Under the Proposed Constitution, shareholders wishing to nominate persons for election to the Board or to properly bring other business before an annual general meeting of shareholders must give timely notice to Trinseo PLC, which must be received not less than 90 nor more than 120 days prior to the first anniversary of the date Trinseo PLC's proxy statement for the prior year was first mailed to shareholders, in comparison to the Articles under which shareholders may bring nominations for directors for vote at an annual meeting if submitted 90 to 120 days prior to the annual meeting date.

5.
Subject to the approval of the Merger Proposal, to approve the creation of distributable profits of Trinseo PLC under Irish law by reducing the entire share premium of Trinseo PLC (or such lesser amount as may be approved by the board of directors of Trinseo PLC) resulting from the allotment and issue of ordinary shares of Trinseo PLC pursuant to the Merger (the "Distributable Profits Proposal");

6.
To elect twelve (12) directors specifically named in the proxy statement, each to serve for a term of one year expiring at the 2022 annual general meeting;

7.
Subject to approval of the Board Increase Proposal, to elect Ms. Victoria Brifo as our thirteenth director, to serve for a term of one year expiring at the 2022 annual general meeting.

8.
To approve, on an advisory basis, the compensation paid by the Company to its named executive officers;

9.
To approve, on an advisory basis, the frequency of advisory votes on the compensation of our named executive officers;

10.
To approve changes to the Company's director compensation program;

11.
To approve the Company's annual accounts prepared in accordance with accounting principles generally accepted in Luxembourg for the year ended December 31, 2020 and its consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States including a footnote reconciliation of equity and net income to International Financial Reporting Standards for the year ended December 31, 2020;

12.
To approve the allocation of the results of the year ended December 31, 2020, including but not limited to the declaration of an annual dividend in the amount of all interim dividends declared and distributed since the Company's last annual general meeting of shareholders;

13.
To approve the granting and discharge of the Company's directors and auditor for the performance of their respective duties during the year ended December 31, 2020;

14.
To ratify the appointment of PricewaterhouseCoopers Société cooperative to be the Company's independent auditor for all statutory accounts required by Luxembourg law for the year ending December 31, 2021;

15.
To ratify the appointment of PricewaterhouseCoopers LLP to be the Company's independent registered public accounting firm for the year ending December 31, 2021.

Third, for the purpose of approving or authorizing any other business properly brought before the General Meeting.

It is expected that the Notice of General Meeting and this proxy statement will first be available to shareholders on or about April 30, 2021. On or before April 30, 2021, the Company will also begin mailing a Notice of Internet Availability of Trinseo's Proxy Materials to shareholders informing them that this proxy statement and voting instructions are available online. As more fully described in that Notice, all shareholders may choose to access proxy materials on the Internet or may request to receive paper copies of the proxy materials.


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Shareholders of record at the close of business on April 20, 2021 are entitled to notice of, and entitled to vote at, the General Meeting and any adjournments or postponements thereof. Whether or not you expect to attend the General Meeting, please complete, sign, date, and promptly return the enclosed proxy card in the envelope that we or your bank or brokerage firm have provided. Your prompt response will ensure that your ordinary shares of Trinseo S.A. are represented at the General Meeting. You can change your vote and revoke your proxy by following the procedures described in this proxy statement.

    By Order of the Board of Directors

 

 

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Angelo N. Chaclas Senior Vice President, Chief Legal Officer,
Chief Compliance Officer and Corporate Secretary

April [    ], 2021

Important Notice Regarding the Availability of Proxy Materials for the General Meeting To Be Held on June 14, 2021: our proxy statement is attached. Financial and other information concerning Trinseo is contained in our Annual Report to shareholders for the fiscal year ended December 31, 2020. The proxy statement and our fiscal 2020 Annual Report to shareholders are available on the Investor Relations section of our website at www.investor.trinseo.com. Additionally, you may access our proxy materials at www.proxyvote.com, a site that does not have "cookies" that identify visitors to the site.


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  Page

Proxy Statement

  1

Questions and Answers About the General Meeting and the Proxy Materials

  2

Questions and Answers About the Merger

  5

Summary of Merger Proposals

  8

Risk Factors

  12

Material Tax Considerations Relating to the Merger

  15

Description of Trinseo Plc Shares

  23

Proposal 1

  35

Proposal 2

  39

Proposal 3

  40

Proposal 4

  57

Proposal 5

  59

Proposal 6

  60

Proposal 7

  74

Corporate Governance

  75

Board Structure and Committee Composition

  78

Our Company's Executive Officers

  80

Transactions with Related Persons

  82

Stock Ownership Information

  83

Securities Authorized for Issuance under Equity Compensation Plans

  85

Delinquent Section 16(a) Reports

  85

Proposal 8

  86

Compensation Discussion and Analysis

  87

Executive Compensation

  98

CEO Pay Ratio

  108

Proposal 9

  109

Director Compensation

  110

Proposal 10

  111

Proposal 11

  112

Proposal 12

  113

Proposal 13

  113

Audit Committee Matters

  114

Proposal 14

  116

Proposal 15

  116

Shareholder Proposals and Director Nominations

  117

Householding

  117

Appendix A

  118

Appendix B

  140

Appendix C

  173


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Proxy Statement

The Board of Trinseo S.A. solicits your proxy for the General Meeting to be held on June 14, 2021, and at any adjournments or postponements of the General Meeting, for the purposes set forth in the Notice of the General Meeting of Shareholders included in this proxy statement. As used in this proxy statement, the terms "we," "us," "our" "Company" or "Trinseo" refer to Trinseo S.A. Proxy materials, including this proxy statement and the Annual Report for our fiscal year ended December 31, 2020 ("fiscal 2020") are being first provided to shareholders on or before April 30, 2021. Our registered address is 26-28, rue Edward Steichen, L 2540 Luxembourg, Grand Duchy of Luxembourg.

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QUESTIONS AND ANSWERS ABOUT THE
GENERAL MEETING AND THE PROXY MATERIALS

QUESTIONS AND ANSWERS ABOUT THE GENERAL MEETING AND THE PROXY MATERIALS

When and where will the General Meeting be held?

We will hold the General Meeting at 12:00 p.m., local time, on Monday, June 14, 2021. Due to the COVID-19 pandemic and ongoing travel restrictions and health and safety concerns, the Board has decided to again hold the General Meeting via teleconference, without a physical meeting, in accordance with the Luxembourg law dated September 23, 2020 on measures on holding meetings of companies and other legal entities ("portant des mesures concernant la tenue de réunions dans les sociétés et dans les autres personnes morales") (as amended). Shareholders will not be able to attend the General Meeting in person, only by teleconference. All shareholders must register if they wish to attend the General Meeting via teleconference. Shareholders may register by going to the Company's voting website, www.proxyvote.com, entering their 16-digit control number found on their proxy card or in their proxy materials, and click on the box labeled "Register for Meeting." Shareholders who register to attend the General Meeting will be given dial-in information for the teleconference, and when dialing into the General Meeting will be asked to confirm their name and control number prior to admission into the teleconference.

Why did I receive a notice in the mail regarding Internet availability of proxy materials instead of a full set of proxy materials?

We provide access to our proxy materials over the Internet. On or about April 30, 2021 we commenced mailing of a Notice of Internet Availability of Proxy Materials to our shareholders of record and beneficial owners. The Notice explains how to access the proxy materials on the Internet and how to vote your proxy for the General Meeting.

If you received the Notice by mail and would like to receive a printed copy of our proxy materials, please follow the instructions for requesting printed materials included in the Notice.

What will shareholders vote on at the General Meeting?

Shareholders will be asked to vote on:

1.
A proposal to approve the Merger between Trinseo PLC as successor company and Trinseo S.A. as transferor company;

2.
To amend our current Articles to increase the size of our Board of Directors to thirteen;

3.
Subject to approval of the Merger Proposal, to approve, on a non-binding advisory basis, the Proposed Constitution to be in effect at the time of the Merger;
4.
Subject to approval of the Merger Proposal, to approve, on a non-binding advisory basis, certain material differences between our Articles and the Proposed Constitution;

5.
Subject to approval of the Merger Proposal, to approve the creation of distributable profits of Trinseo PLC under Irish law by reducing the entire share premium of Trinseo PLC (or such lesser amount as may be approved by the Trinseo PLC Board) resulting from the allotment and issue of Trinseo PLC shares pursuant to the Merger;

6.
To elect twelve (12) directors specifically named in the proxy statement, each to serve for a term of one year;

7.
Subject to the approval of the Board Increase Proposal, to elect a thirteenth director specifically named in the proxy statement, to serve for a term of one year.

8.
To approve, on an advisory basis, the compensation paid by the Company to its named executive officers;

9.
To approve, on an advisory basis, the frequency of advisory votes on the compensation of our named executive officers.

10.
To approve changes to the Company's director compensation program;

11.
To approve the Company's annual accounts prepared in accordance with accounting principles generally accepted in Luxembourg for the year ended December 31, 2020 and its consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States (including a footnote reconciliation of equity and net income to International Financial Reporting Standards for the year ended December 31, 2020) (the "Luxembourg Statutory Accounts");

12.
To approve the allocation of the results of the year ended December 31, 2020 including but not limited to the declaration of an annual dividend in the amount of all interim dividends declared and distributed since the Company's last annual general meeting of shareholders;

13.
To approve the granting and discharge of the Company's directors and statutory auditor for the performance of their respective duties during the year ended December 31, 2020;

14.
To ratify the appointment of PricewaterhouseCoopers Société cooperative ("PwC Luxembourg") to be the Company's independent auditor for all statutory accounts required by Luxembourg law for the year ended December 31, 2021; and

15.
To ratify the appointment of PricewaterhouseCoopers LLP ("PwC") to be the Company's independent registered public accounting firm for the year ended December 31, 2021.

16.
To approve any other business properly brought before the General Meeting.

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QUESTIONS AND ANSWERS ABOUT THE
GENERAL MEETING AND THE PROXY MATERIALS

We do not expect any other matters to be presented at the General Meeting. If other matters are properly presented for voting, the persons named as proxies will vote in accordance with their best judgment on those matters.

Who is entitled to vote at the General Meeting?

Shareholders of record as of the close of business on April 20, 2021 are entitled to vote at the General Meeting. On that date, there were [                           ] of our ordinary shares outstanding. Each ordinary share is entitled to one vote.

What is a shareholder of record?

If your shares are registered directly in your name with our transfer agent, American Stock Transfer & Trust Company, LLC, you are considered the shareholder of record for those shares. As the shareholder of record, you have the right to vote your shares.

If your shares are held in a stock brokerage account or by a bank, or other holder of record, you are considered the beneficial owner of shares held in street name. Your broker, bank, or other holder of record is the shareholder of record for those shares. As the beneficial owner, you have the right to direct your broker, bank, or other holder of record on how to vote your shares.

What constitutes a quorum for consideration of proposals at the General Meeting?

Under our Articles, the holders of a majority of the ordinary shares outstanding and entitled to vote at the General Meeting shall constitute a quorum for the transaction of business at the General Meeting. Ordinary shares represented in person (via teleconference) or by proxy will be counted for purposes of determining whether a quorum is present. Abstentions and broker non-votes (if any) will be treated as present at the General Meeting and will be counted for quorum purposes.

How many votes are required to elect directors and to adopt the other proposals at the General Meeting?

The proposals related to the extraordinary resolutions to approve the Merger (Proposal 1) and to amend the Articles to increase the size of the Board (Proposal 2) require the affirmative vote of two-thirds of the votes validly cast in person or by proxy at the General Meeting. The election of directors and each of the other proposals related to the ordinary resolutions to be voted on require the affirmative vote of a majority of the ordinary shares represented in person or by proxy at the General Meeting and entitled to vote. Advisory votes (Proposals 3, 4, 8 and 9) are deemed approved if passed by a majority of votes cast in person or by proxy at the General Meeting, and the Board takes the voting results under advisement.

How do I vote?

If you are a shareholder of record, you may vote your shares during the General Meeting. If you do not wish to vote during the meeting or if you will not be attending the General Meeting, you

may vote by telephone, or over the Internet, by following the instructions provided in the Notice of Internet Availability of Proxy Materials. If you requested a printed copy of the proxy materials, you may also complete, sign, and date your proxy card and return it in the prepaid envelope that was included with the printed materials.

Beneficial shareholders who held their shares through a broker, bank or other nominee on the record date, who wish to vote their shares by proxy during the General Meeting must register in advance. To register, beneficial holders must first obtain a legal proxy, executed in their favor, from their broker, bank or other nominee. Proof of such legal proxy (e.g., a forwarded email from the beneficial holder's broker, bank or other nominee with the legal proxy attached, or an image of the legal proxy attached to the email) must be sent via email to F21MTGS@trinseo.com and labeled "Legal Proxy" in the subject line. Requests to vote at the General Meeting must be received no later than 6:00p.m. CEST, on Monday, June 7, 2021. Beneficial holders will receive a confirmation of registration by email that they may vote at the General Meeting.

If you are a beneficial holder and do not wish to vote during the meeting, you may vote by following the instructions provided in the Notice of Internet Availability of Proxy Materials you received from the shareholder of record of your shares. If you requested a printed copy of the proxy materials, you should have received a proxy card and voting instructions from the shareholder of record of your shares.

If you are a shareholder of record and submit a signed proxy card for the General Meeting but do not fill out the voting instructions, the persons named as proxy holders will vote the shares represented by your proxy as follows: (1) "FOR" approval of the Common Draft Terms and entry into the Merger; (2) "FOR" the amendment to the Company's Articles to increase the size of its board of directors; (3) subject to approval of the Merger Proposal, "FOR" approval, on an advisory basis, of the Proposed Constitution to be in effect at the time of the Merger; (4) subject to approval of the Merger Proposal, "FOR" approval, on an advisory basis, of the material changes reflected in the Proposed Constitution; (5) subject to approval of the Merger Proposal, "FOR" approval of the creation of distributable profits of Trinseo plc under Irish law by reducing the entire share premium of Trinseo PLC (or such lesser amount as may be approved by the board of directors of Trinseo PLC) resulting from the allotment and issue of ordinary shares of Trinseo PLC pursuant to the Merger (6) "FOR" the election of twelve directors specifically named in the proxy statement, each to serve for a term of one year expiring at the 2022 annual general meeting; (7) "FOR" the election of Ms. Victoria Brifo, subject to approval of the Board Increase Proposal; (8) "FOR" the proposal regarding advisory approval of the compensation paid by the Company to its named executive officers; (9) "1 YEAR" with respect to the advisory vote on the compensation of our named executive officers; (10) "FOR" approval of changes to the Company's director compensation program; (11) "FOR" approval of the Luxembourg Statutory Accounts; (12) "FOR" approval of the allocation of the results of the year ended December 31, 2020; (13) "FOR" the granting and discharge of the Company's directors and auditor for the performance of their respective duties during the year ended

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QUESTIONS AND ANSWERS ABOUT THE
GENERAL MEETING AND THE PROXY MATERIALS

December 31, 2020; (14) "FOR" ratification of the appointment of PwC Luxembourg to be the Company's independent auditor for all statutory accounts required by Luxembourg law for the year ending December 31, 2021; and (15) "FOR" ratification of the appointment of PwC to be the Company's independent registered public accounting firm for the year ending December 31, 2021.

If there are not sufficient votes to approve one or more of the proposals at the General Meeting, in accordance with the Company's Articles, the chair may adjourn the General Meeting to permit the further solicitation of proxies. Additionally, under Luxembourg law, the Board may adjourn the General Meeting for up to four weeks. The persons named as proxies will vote those proxies for such adjournment, unless marked to be voted against the proposal, to permit the further solicitation of proxies. Abstentions and broker non-votes, if any, will not have any effect on the result of the vote for adjournment. If any nominee should become unavailable, your shares will be voted for another nominee selected by the Board or for only the remaining nominees. If your shares are held in the name of a broker or nominee and you do not instruct the broker or nominee how to vote with respect to the election of directors or if you abstain or withhold authority to vote on any matter, your shares will not be counted as having been voted on those matters, but will be counted as in attendance at the meeting for purposes of a quorum.

If you do not vote your shares, you will not have a say on the important issues to be voted upon at the General Meeting.

What happens if I abstain from voting on a matter or my broker withholds my vote?

For extraordinary resolutions (Proposals 1 and 2) and advisory votes (Proposals 3, 4, 8 and 9), abstentions and broker non-votes (described below) are not counted and will have no effect. For each other matter to be considered at the General Meeting, abstentions are treated as shares that are represented and entitled to vote, and therefore abstaining will have the same effect as a negative vote.

A broker non-vote occurs when a broker does not have discretion to vote on a particular non-routine proposal and the broker has not received instructions from their customers as to how to vote on such proposal. Such broker non-votes are not counted as being represented or entitled to vote on such non-routine proposal, which has the effect of reducing the number of affirmative votes needed to approve the proposal.

Should I submit a proxy even if I plan to attend the General Meeting?

To ensure that your vote is recorded promptly, please vote as soon as possible, even if you plan to attend the General Meeting

via teleconference. If you attend the General Meeting and are a shareholder of record, you may also submit your vote during the meeting, and any previous votes that you submitted will be superseded by the vote that you cast during the General Meeting. Internet and phone voting will be cut-off at 11:59 p.m., Eastern Time, on Thursday, June 10, 2020.

Can I revoke my proxy?

Your proxy may be revoked by giving notice of revocation to Trinseo in writing, by accessing the Internet site, by using the toll-free telephone number, or during the General Meeting via teleconference. A shareholder may also change his or her vote by executing and returning to the Company a later-dated proxy, by submitting a later-dated electronic vote through the Internet site, by using the toll-free telephone number or during the General Meeting via teleconference.

The Internet and telephone procedures for voting and for revoking or changing a vote are designed to authenticate shareholders' identities, to allow shareholders to give their voting instructions and to confirm that shareholders' instructions have been properly recorded.

Who will bear the cost of soliciting votes for the General Meeting?

We will bear the expense of the solicitation of proxies for the General Meeting. Solicitation of proxies may be made by mail, in person or telephone by officers, directors and other employees of the Company. We have hired Okapi Partners LLC to aid in the solicitation of proxies. It is estimated that the fee for Okapi Partners LLC will be approximately $35,000 plus reasonable out-of-pocket costs and expenses. Such fee will be paid by the Company.

We will reimburse the Company's banks, brokers, and other custodians, nominees and fiduciaries for their reasonable costs in the preparation and mailing of proxy materials to shareholders.

A shareholder may also choose to vote electronically by accessing the Internet site stated on the Notice of Internet Availability or by using the toll-free telephone number stated on the Notice of Internet Availability. Shareholders that vote through the Internet should understand that there may be costs associated with electronic access, such as usage charges from Internet access providers and telephone companies, which will be borne by the shareholder.

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QUESTIONS AND ANSWERS ABOUT THE MERGER

QUESTIONS AND ANSWERS ABOUT THE MERGER

Why do you want to merge Trinseo S.A. with and into Trinseo PLC?

Our Board believes that giving effect to the Merger will be in the best interests of the Trinseo group and our shareholders. In arriving at this determination, our Board consulted with Trinseo S.A.'s management along with its legal and tax advisors and considered various factors in its deliberations. Our Board concluded that the Merger is likely to result in benefits to the Trinseo group and our shareholders, including: (i) simplifying regulatory requirements, (ii) increasing flexibility on capital deployment such as increased authority to issue new shares or repurchase shares, (iii) providing dividend withholding tax benefits to shareholders and (iv) providing the Trinseo group with operational efficiencies and reduction of its operating and administrative costs. The Merger will also complement the Company's proposed plan to create a global business services center in Ireland. The Board believes that the Irish regime represents a more flexible and favorable legal and regulatory environment for the Company, with beneficial financial and legal infrastructure, without causing any material change to the Company's current business operations, reporting requirements or share listing.

If Trinseo S.A. shareholders approve this proposal, the Merger will effectively change the legal domicile of Trinseo's parent entity from Luxembourg to Ireland and will result in other changes of a legal nature, the most significant of which are described below under the caption "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution" in Proposal 3. For further detail, see "Proposal 1: The Merger—Reasons for the Merger" and "Risk Factors."

When is the Merger expected to be completed?

We currently expect to complete the Merger in October 2021. However, until the issuance of a final order (the "Final Order") by the High Court of Ireland (the "Irish High Court") under the European Communities (Cross-Border Mergers) Regulations 2008 (S.I. No. 157 of 2008), as amended from time to time (the "Irish Regulations"), which we need in order to complete the Merger, the Merger may be abandoned or delayed by Trinseo S.A., even if the Merger has been approved by Trinseo S.A. shareholders and all other conditions to the Merger (other than the approval of the Irish High Court) have been satisfied or waived. For further detail, see "Proposal 1: The Merger—Amendment, Termination or Delay."

Do I have appraisal or redemption rights with respect to the Trinseo S.A. shares I own?

There are no applicable appraisal rights, and the Trinseo S.A. shares are not redeemable.

How will Trinseo PLC shares differ from Trinseo S.A. shares?

Your rights as a Trinseo S.A. shareholder are currently governed by Luxembourg law and our Articles. Following the Merger, you will become a Trinseo PLC shareholder and your rights as a Trinseo PLC shareholder will be governed by Irish law and the Proposed Constitution of Trinseo PLC. The legal system governing companies organized under Irish law differs from the legal system governing companies organized under Luxembourg law. As a result, while many of the principal attributes of Trinseo S.A. shares and Trinseo PLC shares will be similar under Luxembourg and Irish law, differences will exist. We summarize your rights as a Trinseo PLC shareholder under "Description of Trinseo PLC shares" and provide a summary comparison of your rights as a Trinseo S.A. shareholder and Trinseo PLC shareholder under the heading "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution" in Proposal 3. A copy of the Proposed Constitution is attached as Annex B to this Proxy Statement.

Other Matters Related to Trinseo S.A. Shareholders

Will the Merger dilute my economic interest?

No. Trinseo S.A. shareholders will receive a Trinseo PLC ordinary share for every Trinseo S.A. ordinary share they own, on a one-for-one basis. No preferred shares of Trinseo PLC will be issued as a result of the Merger.

If the Merger is approved, do I have to take any action to participate in the Merger?

No. At the date the Merger is deemed effective by the Irish High Court (the "Effective Date"), you will receive, through the transfer agent, an ordinary share of Trinseo PLC for every ordinary share of Trinseo S.A. that you then hold, on a one-for-one basis, without any further action on your part. For further detail, see "Proposal 1: The Merger—No Action Required to Cancel Trinseo S.A. shares and Receive Trinseo PLC shares."

Whom should I contact if I have questions about the Merger?

If you have any questions concerning the information contained in this Proxy Statement, you may contact Trinseo S.A.'s Investor Relations by email at investorrelations@trinseo.com or by telephone at +1 610-240-3221.

Tax Matters Related to Trinseo S.A. Shareholders

Please refer to "Material Tax Considerations Relating to the Merger" for a description of the material U.S. federal income tax, Irish tax and Luxembourg tax consequences of the Merger to Trinseo S.A. shareholders and Trinseo PLC shareholders. Determining the actual tax consequences of the Merger to you may be complex and will depend on your specific situation. We urge you to consult your personal tax advisors.

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QUESTIONS AND ANSWERS ABOUT THE MERGER

Is the Merger taxable to me?

U.S. Federal Income Tax Consequences to U.S. Taxpayers

The Merger is intended to qualify as a "reorganization" within the meaning of Section 368(a) of the Code. If the Merger is so treated as a "reorganization", (i) a U.S. Holder will not recognize any gain or loss as a result of the Merger, (ii) a U.S. Holder's adjusted tax basis in the Trinseo PLC shares received will be equal to the adjusted tax basis of the Trinseo S.A. shares exchanged therefor and (iii) the holding period of the Trinseo PLC shares received as a result of the exchange will include the holding period of Trinseo S.A. shares surrendered in the Merger. For further detail, see "Material Tax Considerations Relating to the Merger—Material U.S. Tax Considerations."

Irish Tax Consequences to Ireland Taxpayers

It is anticipated that the Merger should not be a taxable event from an Irish tax perspective. As a result, it is anticipated that the Merger should not give rise to any Irish capital gains tax consequences for Trinseo S.A. shareholders. For further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations."

Luxembourg Tax Consequences to Luxembourg Taxpayers

We believe that (i) Trinseo S.A. shareholders who are not resident in Luxembourg will generally not be subject to Luxembourg (corporate) income tax in respect of the Merger, subject to certain exceptions, and (ii) Trinseo S.A. shareholders who are resident in Luxembourg may be subject to Luxembourg (corporate) income tax in respect of the Merger, depending on the tax regime applicable to such holder. For further detail, see "Material Tax Considerations Relating to the Merger—Material Luxembourg Tax Considerations."

Will there be Irish stamp duty on the Merger or on the transfer of Trinseo PLC shares after the Merger?

No stamp duty will be payable on the Merger. Irish stamp duty may, depending upon the manner in which Trinseo PLC shares are held, be payable in respect of transfers of Trinseo PLC shares after the Merger. It is expected that for the majority of transfers of Trinseo PLC shares, there should not be any stamp duty. Transfers of Trinseo PLC shares effected by means of the transfer of book-entry interests held in "street name" in Depository Trust Company ("DTC") should not be subject to Irish stamp duty, subject to confirmation by the Irish Revenue Commissioners in advance of the Merger. However, if a shareholder holds their Trinseo PLC shares directly rather than beneficially through a bank, broker or other nominee at DTC, any transfer of the Trinseo PLC shares could be subject to Irish stamp duty (currently at the rate of 1% of the higher of the price paid or the market value of the Trinseo PLC shares acquired). For further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations."

Impact of the Merger on Trinseo S.A.

Will the Merger affect Trinseo S.A.'s operations?

No. The Merger will not change Trinseo S.A.'s day-to-day operations, how we manage our business or how we serve our customers.

How will the Merger affect Trinseo S.A.'s financial reporting?

The Merger will not affect Trinseo S.A.'s current reporting obligations in the United States. After the Merger, Trinseo PLC will continue to prepare financial statements in accordance with U.S. generally accepted accounting principles ("U.S. GAAP"), which are reported in U.S. dollars, and will file reports on Forms 10-K, 10-Q and 8-K with the SEC. Following the Merger, we will no longer file our financial statements with the Luxembourg authorities other than the final accounts up to the Effective Date. Following the Effective Date we will be required to prepare and make available to you financial statements prepared in accordance with Irish law.

Will the Merger have any impact on Trinseo PLC's ability to pay dividends or repurchase shares?

Under Irish law, Trinseo PLC may only pay dividends, make other distributions and, generally effect share repurchases and redemptions from "distributable profits" shown in Trinseo PLC's unconsolidated financial statements prepared in accordance with the Companies Act 2014 of Ireland, as amended (the "Irish Companies Act") and filed with the Irish Companies Registration Office.

Immediately following the Merger, Trinseo PLC will not have any distributable profits. Accordingly, you are being asked to approve the Distributable Profits Proposal, to enable, subject to the effectiveness of the Merger, the creation of distributable profits of Trinseo PLC under Irish law by reducing the entire share premium of Trinseo PLC (or such lesser amount as may be approved by the Trinseo PLC board of directors) resulting from the allotment and issue of Trinseo PLC shares pursuant to the Merger, such that the reserve resulting from the cancellation of such share premium will be treated as distributable profits.

In addition to the approval of Trinseo S.A. shareholders, the Distributable Profits Proposal also requires the approval of the Irish High Court. If the Distributable Profits Proposal is approved by Trinseo S.A. shareholders, and the Merger becomes effective, Trinseo PLC intends to seek the approval of the Irish High Court for the creation of distributable profits as soon as practicable following the Effective Date. Although Trinseo S.A. is not aware of any reason why the Irish High Court would not approve the Distributable Profits Proposal, such approval is a matter of judicial discretion and there is no guarantee that approval will be provided.

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QUESTIONS AND ANSWERS ABOUT THE MERGER

While the Trinseo S.A. Board recommends that Trinseo S.A. shareholders vote for the Distributable Profits Proposal, the passing of the Distributable Profits Proposal is not a condition to the Merger. If the Distributable Profits Proposal is not approved by Trinseo S.A. shareholders and the Irish High Court, Trinseo PLC will not be able to pay dividends, make other distributions and, generally, effect share repurchases and redemptions until such time as it has otherwise generated sufficient distributable profits from its operational activities following the Merger.

For further detail, see "Risk Factors" and "Proposal 5: The Distributable Profits Proposal."

Is the Merger a taxable transaction for Trinseo S.A.?

The Merger is in principle a taxable transaction for Trinseo S.A. pursuant to which gains and or losses may be recognized for Luxembourg corporate income tax purposes. However, Trinseo S.A. expects that no Luxembourg corporate income tax will be due as a result of the Merger, due to a combination of (i) the application of the Luxembourg "participation exemption" in respect of gains derived from certain qualifying participations in subsidiaries, and (ii) the availability of tax loss carry forwards.

Trinseo S.A. does not believe that the Merger will be a taxable event from an Irish tax perspective. As a result, it is anticipated that the Merger will not give rise to any Irish capital gains tax consequences for Trinseo S.A.

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SUMMARY OF MERGER PROPOSALS

Summary of Merger Proposals

This summary highlights selected information from this Proxy Statement concerning the Merger Proposal. It does not contain all of the information that may be important to you. To understand the Merger more fully, and for a more complete legal description of the Merger, you should carefully read the entire Proxy Statement, including the Annexes. The Common Draft Terms, in the form attached as Annex A to this Proxy Statement, is the legal document that governs the Merger. The Proposed Constitution substantially in the form attached to this Proxy Statement as Annex B, will govern Trinseo PLC upon completion of the Merger. We encourage you to read those documents carefully.

Parties to the Merger

Trinseo S.A.    Trinseo S.A. (NYSE: TSE) is a public limited liability company (société anonyme) formed in 2010 and existing under the laws of Luxembourg. We are a leading global materials company and manufacturer of plastics, latex binders and synthetic rubber, including various advanced specialty products and sustainable solutions. Our products are incorporated into a wide range of our customers' products throughout the world, including products for automotive applications, tires, carpet and artificial turf backing, coated paper, specialty paper and packaging board, food packaging, appliances, medical devices, consumer electronics and construction applications, among others. The Company's registered office is at 26-28, rue Edward Steichen, L 2540 Luxembourg, Grand Duchy of Luxembourg.

Trinseo PLC.    Trinseo Limited was incorporated as a private limited company under the laws of Ireland on May 27, 2015 as "Tribus Investments Limited" and was renamed "Trinseo Limited" on April 7, 2021. Prior to the Effective Date, Trinseo Limited will be re-registered as an Irish public limited company and renamed "Trinseo PLC". To date, Trinseo Limited has not engaged in any business or conducted any activities other than in connection with its formation and the Merger. The registered office of Trinseo PLC will be Sir John, Rogerson's Quay, Riverside One, Dublin 2, D02 X576, Ireland and Trinseo PLC's telephone number will be +1-610-240-3200.

The Merger

Trinseo S.A. shareholders are being asked to approve the Merger in accordance with the Common Draft Terms at the General Meeting. Contingent upon the approval of the Common Draft Terms, and assuming the other conditions to the Merger in the Common Draft Terms are satisfied or waived, on the Effective Date Trinseo S.A. shareholders will receive an ordinary share of Trinseo PLC for every ordinary share of Trinseo S.A. that they then hold, on a one-for-one basis. As a result of the Merger, Trinseo PLC will become our new public holding company with a NYSE trading symbol of "TSE".

Steps Required to Effect the Merger

On June 14, 2021, we will hold the General Meeting to allow shareholders of record to vote on the Merger proposals, including approval of the Merger and the Common Draft Terms.

Luxembourg.

After the Merger Proposal and resolution to enter into the Merger has been approved by Trinseo S.A. shareholders at the General Meeting, the following steps must be taken in Luxembourg in order to effect the Merger:

    Luxembourg notary before whom the General Meeting is held will issue a pre-merger certificate attesting that all formalities required in Luxembourg in connection with the merger have been duly effected which shall be delivered to Trinseo PLC in accordance with Art. 1021-12(2) of the Luxembourg law of 10 August 1915 on commercial companies as amended from time to time (the "Luxembourg Law");

    Upon receipt of the Final Order, the Luxembourg Trade and Company Register will deregister Trinseo S.A. which will have ceased to exist as of the Effective Date.

Ireland.

Following shareholder approval, the following steps must occur for Trinseo PLC to complete the Merger:

    Application will be made to the Irish High Court for a pre-merger certificate; and

    Subject to issuance of a pre-merger certificate by the Irish High Court and the issuance of a pre-merger certificate by a Luxembourg civil law notary, an application will be made to the Irish High Court for an order to confirm legal scrutiny of the Merger and to set the Effective Date. The hearing of this application will be advertised in Iris Oifigiúil, the international editions of The Financial Times and/or The Wall Street Journal and/or such other publications as the Irish High Court may prescribe. Trinseo S.A. shareholders may attend the approval hearing and make representations at such meeting.

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SUMMARY OF MERGER PROPOSALS

Effectiveness.    If all of the conditions are satisfied or waived (and we do not abandon the Merger before obtaining the Irish High Court's Order), the Merger will take effect on the Effective Date. We currently anticipate the Merger to be effective in October 2021. Once the Merger takes effect as provided for in the Irish Regulations, it may not be declared null and void, and the Final Order specifying the Effective Date shall constitute conclusive evidence of the effectiveness of the Merger.

In connection with the Merger, the following steps will occur by operation of law on the Effective Date:

1.
Trinseo S.A. will be merged with and into Trinseo PLC, with Trinseo PLC as the surviving entity, and Trinseo S.A. will cease to exist upon consummation of the Merger;

2.
all assets and liabilities of Trinseo S.A. as at the Effective Date shall transfer to, and be assumed by Trinseo PLC by universal succession of title and by operation of law;

3.
the activities of the Trinseo S.A. business shall be continued by Trinseo PLC;

4.
each Trinseo S.A. shareholder (other than Trinseo S.A.) will receive an ordinary share of Trinseo PLC for every ordinary share of Trinseo S.A. that they then hold, on a one-for-one basis;

5.
in accordance with Luxembourg Law, all Trinseo S.A. treasury shares held by Trinseo S.A. will be canceled by operation of law;

6.
all legal proceedings pending by or against Trinseo S.A. will be continued with the substitution, for Trinseo S.A., of Trinseo PLC as a party; and

7.
contracts, agreements or instruments to which Trinseo S.A. is a party will by operation of law succeed to Trinseo S.A. and be construed and have effect as if Trinseo PLC had been a party thereto instead of Trinseo S.A., and Trinseo PLC will have the same rights and be subject to the same obligations to which Trinseo S.A. is subject to under such contracts, agreements or instruments.

8.
without prejudice to the foregoing, the consequences of the Merger set out in Regulation 19(1) of the Irish Regulations and Art 1021-17 of the Luxembourg Law shall apply to the Merger.

As a result of the Merger, Trinseo S.A. shareholders will become Trinseo PLC shareholders, and Trinseo S.A. will cease to exist.

After the Merger, you will own an interest in a company that will continue to conduct the same functions as conducted by Trinseo S.A. before the Merger. The number of Trinseo PLC shares you will own immediately following the Merger will be the same as the number of Trinseo S.A. shares you owned immediately before the Merger.

Upon completion of the Merger, we will remain subject to SEC reporting requirements and will continue to report our consolidated financial results in U.S. dollars and in accordance with U.S. GAAP. As required by Irish law, in connection with annual general meetings of Trinseo PLC commencing with its 2022 annual general meeting, the Trinseo PLC Irish statutory accounts will also be made available to Trinseo PLC shareholders.

Reasons for the Merger (See page 36)

Our Board believes that giving effect to the Merger will be in the best interests of the Trinseo group and our shareholders. In arriving at this determination, our Board consulted with Trinseo S.A.'s management along with its legal and tax advisors and considered various factors in its deliberations. Our Board concluded that the Merger will simplify our regulatory and governance requirements, provide dividend withholding tax benefits to shareholders, allow for increased flexibility to allocate capital through share issuances or repurchases, and provide Trinseo with other operational efficiencies and cost reductions. The Merger will also complement the Company's proposed plan to create a global business services center in Ireland. If Trinseo S.A. shareholders approve this proposal, the Merger will effectively change Trinseo S.A.'s legal domicile from Luxembourg to Ireland and will result in other changes of a legal nature, the most significant of which are described below under the caption "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution" in Proposal 3.

We cannot assure you that the anticipated benefits of the Merger will be realized. In addition to the potential benefits described above, the Merger will expose us and you to some risks. These risks include, but are not limited to: changes to your rights as a Trinseo S.A. shareholder; the potential application of stamp duty on the transfer of Trinseo PLC shares after the Merger; the potential application of Irish dividend withholding tax; and the potential application of Irish capital acquisitions tax to a gift or inheritance of Trinseo PLC shares.

For further detail, see "Proposal 1: The Merger—Reasons for the Merger" and "Risk Factors" for more information.

Tax Considerations of the Merger (See page 15)

U.S. Federal Income Tax.    The Merger is intended to qualify as a "reorganization" within the meaning of Section 368(a) of the Code. If the Merger is so treated as a "reorganization", (i) a U.S. Holder will not recognize any gain or loss as a result of the Merger, (ii) a U.S. Holder's adjusted tax basis in the Trinseo PLC shares received will be equal to the adjusted tax basis of the Trinseo S.A. shares exchanged therefor and (iii) the holding period of the Trinseo PLC shares received as a result of the exchange will include the holding period of Trinseo S.A. shares surrendered in the Merger.

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Irish Tax.    It is anticipated that the Merger should not be a taxable event from an Irish tax perspective. As a result, it is anticipated that the Merger should not give rise to any Irish capital gains tax consequences for Trinseo S.A. shareholders. No stamp duty will be payable on the Merger. Irish stamp duty may, depending upon the manner in which Trinseo PLC shares are held, be payable in respect of transfers of Trinseo PLC shares after the Merger. It is expected that for the majority of transfers of Trinseo PLC shares following the Merger, no stamp duty should arise. Transfers of Trinseo PLC shares effected by means of the transfer of book-entry interests in DTC should not be subject to Irish stamp duty, subject to confirmation by the Irish Revenue Commissioners in advance of the Merger. However, if a shareholder holds their Trinseo PLC shares directly rather than beneficially through DTC, any transfer of the Trinseo PLC shares could be subject to Irish stamp duty (currently at the rate of 1% of the higher of the price paid or the market value of the shares acquired). For further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations."

Luxembourg Tax.    We believe that (i) Trinseo S.A. shareholders who are not resident in Luxembourg will generally not be subject to Luxembourg (corporate) income tax in respect of the Merger, subject to certain exceptions, and (ii) Trinseo S.A. shareholders who are resident in Luxembourg may be subject to Luxembourg (corporate) income tax in respect of the Merger, depending on the tax regime applicable to such holder. For further detail, see "Material Tax Considerations Relating to the Merger—Material Luxembourg Tax Considerations."

You should consult your personal tax advisors concerning the tax consequences of receiving, holding, disposing of, and receiving dividends on, Trinseo PLC shares received pursuant to the Merger.

Comparison of Rights of Shareholders and Governance (See page 40)

Your rights as a Trinseo S.A. shareholder are currently governed by Luxembourg law and our Articles. Following the Merger, you will become a Trinseo PLC shareholder and your rights as a Trinseo PLC shareholder will be governed by Irish law and the Proposed Constitution. The legal system governing companies organized under Irish law differs from the legal system governing companies organized under Luxembourg law. As a result, while many of the principal attributes of Trinseo S.A. shares and Trinseo PLC shares will be similar under Luxembourg and Irish law, differences will exist.

We summarize your rights as a Trinseo PLC shareholder under "Description of Trinseo PLC shares" and provide a summary comparing your rights as a Trinseo S.A. shareholder and a Trinseo PLC shareholder under the heading "Comparison of Rights of Shareholders and Governance" in Proposal 3. A copy of the Proposed Constitution is attached as Annex B to this Proxy Statement.

Stock Exchange Listing

The Merger is not expected to affect our stock exchange listing on the New York Stock Exchange (the "NYSE"). Trinseo S.A. shares are expected to continue to trade on the NYSE until the Effective Date. Immediately following the Effective Date, Trinseo PLC shares will be listed on the NYSE under the symbol "TSE," the same symbol under which Trinseo S.A. shares are currently listed.

Upon completion of the Merger, we will remain subject to SEC reporting requirements, the mandates of the Sarbanes-Oxley Act of 2002 and the applicable corporate governance rules of the NYSE, and we will continue to report our consolidated financial results in U.S. dollars and in accordance with U.S. GAAP.

Accounting Treatment of the Merger (See page 38)

Under U.S. GAAP, the Merger represents a transaction between entities under common control. Assets and liabilities transferred between entities under common control are accounted for at historical cost. Accordingly, the assets and liabilities of Trinseo PLC will be reflected at their carrying amounts in the accounts of Trinseo S.A. at the time of the Merger .

Irish Constitution Proposal

We are asking shareholders to approve, by non-binding advisory vote, the Proposed Constitution of Trinseo PLC, in the form attached hereto as Annex B (Proposal 3). The Proposed Constitution is the governing document which will be in effect at the time the Merger is completed. If the Merger is not approved, this proposal will have no effect, but the Merger is not conditioned on the separate approval of this advisory proposal. We are asking shareholders to vote for the Proposed Constitution on an advisory basis, to allow shareholders the opportunity to vote for the Proposed Constitution separately from the Merger Proposal. A comparison of the rights of Trinseo S.A. shareholders under our existing Articles and Luxembourg law to the rights of Trinseo PLC shareholders under the Proposed Constitution and Irish law is set forth in detail in the language of the proposal. We encourage you to read these differences carefully when making your decision on how to vote.

We strongly encourage all shareholders that vote "for" the Merger Proposal to also vote "for" the Irish Constitution Proposal, to allow the Company to proceed with the Merger as intended and set forth in the Merger Proposal.

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SUMMARY OF MERGER PROPOSALS

Advisory Constitution Proposals

We are also asking shareholders to vote, on a non-binding advisory basis, to approve certain differences between our Articles and the Proposed Constitution (Proposal 4). These differences are being presented as three separate advisory proposals, and pertain to (a) changes in our authorized share capital; (b) changes in our share issuance authority and preemptive rights, and (c) changes to the advance notice provision for shareholder director nominations. If the Merger is not approved, this proposal will have no effect, but the Merger is not conditioned on the separate approval of these advisory proposals.

We strongly encourage shareholders who vote "for" the Merger Proposal to also vote "for" these three advisory proposals. We believe these provisions are necessary to adequately address the needs of Trinseo PLC following the Merger.

Description of Distributable Profits

Under Irish law, Trinseo PLC may only pay dividends, make other distributions and, generally, effect share repurchases and redemptions from "distributable profits" shown in Trinseo PLC's unconsolidated financial statements prepared in accordance with the Irish Companies Act and filed with the Irish Companies Registration Office.

Immediately following the Merger, Trinseo PLC will not have any distributable profits of its own. Accordingly, you are being asked to approve the Distributable Profits Proposal (Proposal 5), to enable, subject to the effectiveness of the Merger, the creation of distributable profits of Trinseo PLC under Irish law by reducing the entire share premium of Trinseo PLC as created by the Merger (or such lesser amount as may be approved by the Trinseo PLC Board). Trinseo PLC must also seek approval from the Irish High Court.

The Trinseo S.A. Board recommends that Trinseo S.A. shareholders vote for the Distributable Profits Proposal, though it is not a condition to the Merger. If the Distributable Profits Proposal is not approved by Trinseo S.A. shareholders and the Irish High Court, Trinseo PLC will not be able to pay dividends, make other distributions and, generally, effect share repurchases and redemptions until such time as it has otherwise generated sufficient distributable profits from its operational activities following the Merger.

Recommendation of the Board

Our Board recommends that Trinseo S.A. shareholders vote "FOR" the Merger Proposal, "FOR" the Irish Constitution Proposal, "FOR" the Advisory Constitution Proposals and "FOR" the Distributable Profits Proposal.

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Risk Factors

Before you decide how to vote, you should carefully consider the following risk factors related to the Merger, in addition to the other information contained in this Proxy Statement, including, without limitation, our Form 10-K and subsequent filings with the SEC.

Your rights as a Trinseo S.A. shareholder will change as a result of the Merger due to differences between Irish law and Luxembourg law.

Your rights as a Trinseo S.A. shareholder are currently governed by Luxembourg law and our Articles. Following the Merger, you will become a Trinseo PLC shareholder and your rights as a Trinseo PLC shareholder will be governed by Irish law and the Proposed Constitution. The legal system governing companies organized under Irish law differs from the legal system governing companies organized under Luxembourg law. As a result, while many of the principal attributes of Trinseo S.A. shares and Trinseo PLC shares will be similar under Luxembourg and Irish law, differences will exist, which, in some cases, may provide fewer protections for Trinseo PLC shareholders. We summarize your rights as a Trinseo PLC shareholder under "Description of Trinseo PLC shares" and provide a summary comparing your rights as a Trinseo S.A. shareholder and a Trinseo PLC shareholder under the heading "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution" in Proposal 3.

Attempted takeovers of Trinseo PLC will be subject to the Irish Takeover Rules and will be under the supervisory jurisdiction of the Irish Takeover Panel.

Following the completion of the Merger, Trinseo PLC will be subject to the Irish Takeover Panel Act 1997, as amended, and the Irish Takeover Rules promulgated thereunder, which regulate the conduct of takeovers of, and certain other relevant transactions affecting, Irish public limited companies listed on certain stock exchanges, including the NYSE.

Under the Irish Takeover Rules, if an acquisition of Trinseo PLC shares were to increase the aggregate holding of the acquirer and its concert parties to a level that represents 30% or more of the voting rights of Trinseo PLC, the acquirer and, in certain circumstances, its concert parties would be required (except with the consent of the Irish Takeover Panel) to make an offer for the outstanding Trinseo PLC shares at a price not less than the highest price paid by the acquirer or its concert parties for Trinseo PLC shares during the previous 12 months. This requirement would also be triggered by an acquisition of Trinseo PLC shares by a person holding (together with its concert parties) Trinseo PLC shares that represent between 30% and 50% of the voting rights in the company if the effect of such acquisition were to increase that person's percentage of the voting rights by 0.05% within a 12-month period.

For a description of certain takeover provisions applicable to Trinseo PLC, see "Description of Trinseo PLC shares—Irish Takeover Rules" beginning on page 29.

Anti-takeover provisions in the Proposed Constitution could make an acquisition of Trinseo PLC more difficult, limit attempts by Trinseo PLC shareholders to replace or remove our directors and management team and limit the market price of Trinseo PLC shares.

The Proposed Constitution will contain provisions that may delay or prevent a change of control, discourage bids at a premium over the market price of Trinseo PLC shares and adversely affect the market price of Trinseo PLC shares and the voting and other rights of Trinseo PLC shareholders. These provisions include: (1) permitting the Trinseo PLC board of directors (the "Trinseo PLC Board") to issue preference shares without shareholder approval, with such rights, preferences and privileges as they may designate; (2) allowing the Trinseo PLC Board to adopt a shareholder rights plan upon such terms and conditions as it deems expedient; (3) establishing an advance notice procedure for shareholder proposals to be brought before the annual general meeting, including proposed nominations of persons for election to the Trinseo PLC Board; (4) permitting the Trinseo PLC Board or directors to fill vacancies on the Trinseo PLC Board in certain circumstances; and (5) imposing particular approvals and other requirements in relation to certain business combinations. For a description of certain takeover provisions applicable to Trinseo PLC, see "Description of Trinseo PLC shares—Irish Takeover Rules" beginning on page 29.

These provisions do not make Trinseo PLC immune from takeovers. However, these provisions may frustrate or prevent any attempts by shareholders to replace or remove the management team by making it more difficult for shareholders to replace members of the Trinseo PLC Board.

If the Distributable Profits Proposal is not approved by Trinseo S.A. shareholders and the Irish High Court, Trinseo PLC will not be able to pay dividends, make other distributions and, generally, effect share repurchases and redemptions until such time as it has otherwise generated sufficient distributable profits from its operational activities following the Merger.

Under Irish law, Trinseo PLC may only pay dividends, make other distributions and, generally, effect share repurchases and redemptions from "distributable profits" shown in Trinseo PLC's unconsolidated financial statements prepared in accordance with the Irish Companies Act and filed with the Irish Companies Registration Office.

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Immediately following the Merger, Trinseo PLC will not have any distributable profits. Accordingly, you are being asked to approve the Distributable Profits Proposal, to enable, subject to the effectiveness of the Merger, the creation of distributable profits of Trinseo PLC under Irish law by reducing the entire share premium of Trinseo PLC (or such lesser amount as may be approved by the Trinseo PLC Board) resulting from the allotment and issuance of Trinseo PLC shares pursuant to the Merger, such that the reserve resulting from the cancellation of such share premium will be treated as distributable profits.

In addition to the approval of Trinseo S.A. shareholders, the Distributable Profits Proposal also requires the approval of the Irish High Court. If the Distributable Profits Proposal is approved by Trinseo S.A. shareholders prior to the Effective Date and the Merger becomes effective, Trinseo PLC intends to seek the approval of the Irish High Court for the Distributable Profits Proposal as soon as practicable following the Effective Date. Although Trinseo S.A. is not aware of any reason why the Irish High Court would not approve the Distributable Profits Proposal, such approval is a matter of judicial discretion and there is no guarantee that such approval will be forthcoming.

If the Distributable Profits Proposal is not approved by Trinseo S.A. shareholders and the Irish High Court, Trinseo PLC will not be able to pay dividends, make other distributions and, generally, effect share repurchases and redemptions until such time as it has otherwise generated sufficient distributable profits from its operational activities following the Merger.

We may choose to abandon or delay the Merger. In addition, we may not be able to receive the requisite governmental approvals to consummate the Merger.

We currently expect to complete the Merger in October 2021. However, our Board may delay the Merger for a significant time or may abandon the Merger after the General Meeting and before the issuance of the Final Order because, among other reasons, of a determination by our Board that completing the Merger is no longer in our best interest or the best interests of Trinseo S.A. shareholders or may not result in the benefits we expect. Additionally, we may not be able to obtain the requisite court or other approvals. For further detail, see "Proposal 1: The Merger—Conditions to the Consummation of the Merger" and "Proposal 1: The Merger—Amendment, Termination or Delay."

If Trinseo PLC shares are not eligible for deposit and clearing within the facilities of DTC, then transactions in Trinseo PLC shares may be disrupted.

The facilities of DTC are a widely used mechanism that allow for rapid electronic transfers of securities between the participants in the DTC system, which include many large banks and brokerage firms.

Upon the completion of the Merger, Trinseo PLC shares will be eligible for deposit and clearing within the DTC system. We expect to enter into arrangements with DTC whereby Trinseo PLC will agree to indemnify DTC for any Irish stamp duty that may be assessed upon it as a result of its service as a depositary and clearing agency for Trinseo PLC shares. We expect that these actions, among others, will result in DTC agreeing to accept the shares for deposit and clearing within its facilities upon completion of the Merger.

DTC is not obligated to accept Trinseo PLC shares for deposit and clearing within its facilities at the closing of the Merger and, even if DTC does initially accept the Trinseo PLC shares, it will generally have discretion, as it currently has with regard to Trinseo S.A. shares, to cease to act as a depositary and clearing agency for the shares. If DTC determined prior to the completion of the Merger that Trinseo PLC shares are not eligible for clearance within the DTC system, then we would not expect to complete the transactions contemplated by this Proxy Statement in their current form. However, if DTC determined at any time after the completion of the Merger that Trinseo PLC shares were not eligible for continued deposit and clearance within its facilities, then we believe Trinseo PLC shares would not be eligible for continued listing on a U.S. securities exchange and trading in Trinseo PLC shares would be disrupted. Although we expect Trinseo PLC would pursue alternative arrangements to preserve its listing and maintain trading, any such disruption could have a material adverse effect on the trading price of Trinseo PLC shares.

Transfers of Trinseo PLC shares, other than by means of the transfer of book-entry interests in the DTC, may be subject to Irish stamp duty.

It is expected that for the majority of transfers of Trinseo PLC shares, no stamp duty should arise. Transfers of Trinseo PLC shares effected by means of the transfer of book-entry interests in DTC should not be subject to Irish stamp duty, subject to confirmation by the Irish Revenue Commissioners in advance of the Merger. However, if a shareholder holds their Trinseo PLC shares directly rather than beneficially through DTC, any transfer of the Trinseo PLC shares could be subject to Irish stamp duty (currently at the rate of 1% of the higher of the price paid or the market value of the shares acquired).

A Trinseo PLC shareholder who directly holds Trinseo PLC shares of record may transfer those shares into his or her own broker account to be held through DTC (or vice versa) and this should not give rise to Irish stamp duty provided that there is no change in the beneficial ownership of the shares as a result of the transfer and the transfer is not in contemplation of a sale of the shares by a beneficial owner to a third party.

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Due to the potential Irish stamp duty charge on transfers of Trinseo PLC shares held outside DTC, those Trinseo S.A. shareholders who do not hold their Trinseo S.A. shares through DTC (or through a broker who in turn holds such shares through DTC) should, upon completion of the Merger, consider holding Trinseo PLC shares received by them through DTC.

For further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations."

You should consult your personal tax advisors as to the tax consequences of disposing of Trinseo PLC shares received pursuant to the Merger.

Dividends you receive after the Merger may be subject to Irish dividend withholding tax ("DWT"), subject to exemptions.

As an Irish tax resident company, we may be required to deduct DWT (currently at the rate of 25%) from dividends paid on Trinseo PLC shares unless Trinseo PLC shareholders qualify for a DWT exemption. Trinseo PLC shareholders resident in the EU, and other countries with which Ireland has a tax treaty (which includes the United States) should generally be eligible for an exemption from DWT, provided that, in each case, they file a valid DWT Form with the Irish Revenue Commissioners. However, Trinseo PLC shareholders residing in other countries may be subject to DWT. For further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations."

You should consult your personal tax advisors as to the tax consequences of receiving dividends on Trinseo PLC shares.

Trinseo PLC shares received by means of a gift or inheritance may be subject to Irish capital acquisitions tax ("CAT"), subject to any exemptions and reliefs.

CAT could apply to a gift or inheritance of Trinseo PLC shares irrespective of the place of residence, ordinary residence or domicile of the parties. This is because Trinseo PLC shares are regarded as property situated in Ireland as the share register of Trinseo PLC must be held in Ireland. The person who receives the gift or inheritance has primary liability for CAT. For further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations."

We recommend that you consult your personal advisors to consider your estate planning needs, including transfers of Trinseo PLC shares to family members and charitable organizations.

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Material Tax Considerations Relating to the Merger

Material U.S. Federal Income Tax Considerations

The following is a general discussion of the material U.S. federal income tax consequences of the Merger to U.S. Holders (as defined below) of Trinseo S.A. shares, and of the subsequent ownership and disposition of Trinseo PLC shares received by such U.S. Holders in the Merger. This discussion does not address any U.S. federal income tax consequences of the Merger to non-U.S. Holders, except to the limited extent discussed below under "U.S. Federal Income Tax Consequences of the Merger to Trinseo S.A. Shareholders—Material Tax Consequences to Non-U.S. Holders".

This discussion is based on provisions of the Internal Revenue Code of 1986, as amended, the Treasury Regulations promulgated thereunder (whether final, temporary, or proposed), administrative rulings of the U.S. Internal Revenue Service (the "IRS"), and judicial decisions all as in effect on the date hereof, and all of which are subject to differing interpretations or change, possibly with retroactive effect. This discussion does not purport to be a complete analysis or listing of all potential U.S. federal income tax considerations that may apply to a U.S. Holder as a result of the Merger or as a result of the ownership and disposition of Trinseo PLC shares. In addition, this discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular U.S. Holders nor does it take into account the individual facts and circumstances of any particular U.S. Holders that may affect the U.S. federal income tax consequences to such U.S. Holder, and accordingly, is not intended to be, and should not be construed as, tax advice. This discussion does not address the U.S. federal 3.8% Medicare tax imposed on certain net investment income or any aspects of U.S. federal taxation other than those pertaining to the income tax (including any gift, estate or alternative minimum tax), nor does it address any tax consequences arising under any U.S. state and local tax laws. U.S. Holders should consult their own tax advisors regarding such tax consequences in light of their particular circumstances.

No ruling has been requested or will be obtained from the IRS regarding the U.S. federal income tax consequences of the Merger or any other related matter; thus, there can be no assurance that the IRS will not challenge the U.S. federal income tax treatment described below or that, if challenged, such treatment will be sustained by a court.

This summary is limited to considerations relevant to U.S. Holders that hold Trinseo S.A. shares, and, following consummation of the Merger, Trinseo PLC shares, as "capital assets" within the meaning of section 1221 of the Code (generally, property held for investment). This discussion does not address all aspects of U.S. federal income taxation that may be important to U.S. Holders in light of their individual circumstances, including U.S. Holders subject to special treatment under the U.S. tax laws, such as, for example:

    banks or other financial institutions, underwriters, or insurance companies;

    traders in securities who elect to apply a mark-to-market method of accounting;

    real estate investment trusts and regulated investment companies;

    tax-exempt organizations, qualified retirement plans, individual retirement accounts, or other tax-deferred accounts;

    expatriates or former long-term residents of the United States;

    partnerships or other pass-through entities or investors in such entities;

    dealers or traders in securities, commodities or currencies;

    grantor trusts;

    U.S. Holders whose "functional currency" is not the U.S. dollar;

    persons who received Trinseo S.A. shares or Trinseo PLC shares through the issuance of restricted stock under an equity incentive plan or through a tax-qualified retirement plan or otherwise as compensation;

    persons who own (directly or through attribution) 10% or more (by vote or value) of the outstanding Trinseo S.A. shares, or, after the Merger, the outstanding Trinseo PLC shares; or

    U.S. Holders holding Trinseo S.A. shares, or, after the Merger, Trinseo PLC shares, as a position in a "straddle," as part of a "synthetic security" or "hedge," as part of a "conversion transaction," or other integrated investment or risk reduction transaction.

As used in this Proxy Statement, the term "U.S. Holder" means a beneficial owner of Trinseo S.A. shares, and, after the Merger, Trinseo PLC shares received in the Merger, that is, for U.S. federal income tax purposes:

    an individual who is a citizen or resident of the United States;

    a corporation or other entity taxable as a corporation created or organized in or under the laws of the United States or any State thereof or the District of Columbia;

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    an estate the income of which is subject to U.S. federal income tax regardless of its source; or

    a trust (i) if a court within the United States is able to exercise primary supervision over the administration of the trust and one or more U.S. persons have the authority to control all substantial decisions of the trust, or (ii) that has a valid election in effect under applicable Treasury Regulations to be treated as a U.S. person for U.S. federal income tax purposes.

As used in this Proxy Statement, the term "non-U.S. Holder" means a beneficial owner of Trinseo S.A. shares, and, after the Merger, Trinseo PLC shares received in the Merger, other than a U.S. Holder or an entity or arrangement treated as a partnership for U.S. federal income tax purposes.

If a partnership, including for this purpose any entity or arrangement that is treated as a partnership for U.S. federal income tax purposes, is a beneficial owner of Trinseo S.A. shares, and, following consummation of the Merger, Trinseo PLC shares received in the Merger, the U.S. federal income tax treatment of a partner in such partnership generally will depend on the status of the partner and the activities of the partnership. A U.S. Holder that is a partnership and the partners in such partnership should consult their own tax advisors with regard to the U.S. federal income tax consequences of the Merger and the subsequent ownership and disposition of Trinseo PLC shares received in the Merger.

THIS SUMMARY DOES NOT PURPORT TO BE A COMPREHENSIVE ANALYSIS OR DESCRIPTION OF ALL POTENTIAL U.S. FEDERAL INCOME TAX CONSEQUENCES OF THE MERGER. TRINSEO S.A. SHAREHOLDERS AND TRINSEO PLC SHAREHOLDERS SHOULD CONSULT WITH THEIR TAX ADVISORS REGARDING THE PARTICULAR TAX CONSEQUENCES TO THEM OF THE MERGER AND OF THE OWNERSHIP AND DISPOSITION OF TRINSEO PLC SHARES AFTER THE MERGER, INCLUDING THE APPLICABILITY AND EFFECTS OF U.S. FEDERAL, STATE, LOCAL, AND OTHER TAX LAWS.

U.S. Federal Income Tax Consequences of the Merger to Trinseo S.A. and Trinseo PLC

For U.S. federal income tax purposes, the Merger is intended to qualify as a "reorganization" within the meaning of Section 368(a)(1)(F) of the Code, i.e. a "mere change in identity, form, or place of organization of one corporation." Assuming that the Merger is treated as a reorganization under Section 368(a)(1)(F), neither Trinseo S.A. nor Trinseo PLC are expected to recognize any gain or loss for U.S. federal income tax purposes as a result of the Merger.

U.S. Federal Income Tax Consequences of the Merger to Trinseo S.A. Shareholders

Material Tax Consequences to U.S. Holders

Assuming that the Merger is treated as a reorganization under Section 368(a)(1)(F), (i) a U.S. Holder will not recognize any gain or loss as a result of the Merger, (ii) a U.S. Holder's adjusted tax basis in the Trinseo PLC shares received will be equal to the adjusted tax basis of the Trinseo S.A. shares exchanged therefor and (iii) the holding period of the Trinseo PLC shares received as a result of the exchange will include the holding period of Trinseo S.A. shares surrendered in the Merger.

Material Tax Consequences to Non-U.S. Holders

A non-U.S. holder generally will not be subject to U.S. federal income or withholding tax on gain realized, if any, on the exchange of Trinseo S.A. shares for Trinseo PLC shares in the Merger.

U.S. Federal Income Tax Consequences to U.S. Holders of the Ownership and Disposition of Trinseo PLC shares

The following discussion is a summary of certain material U.S. federal income tax consequences of the ownership and disposition of Trinseo PLC shares to U.S. Holders who receive such Trinseo PLC shares pursuant to the Merger.

Distributions on Trinseo PLC shares

The gross amount of any distribution on Trinseo PLC shares that is made out of Trinseo PLC's current or accumulated earnings and profits (as determined for U.S. federal income tax purposes) generally will be included in the gross income of a U.S. Holder as ordinary dividend income on the date such distribution is actually or constructively received by such U.S. Holder. Any such dividends paid to corporate U.S. Holders generally will not qualify for the dividends-received deduction that may otherwise be allowed under the Code. In general, the dividend income would be treated as foreign source, passive income for U.S. federal foreign tax credit limitation purposes.

Dividends received by non-corporate U.S. Holders (including individuals), subject to the discussion below under "—Passive Foreign Investment Company Status," from a "qualified foreign corporation" may be eligible for reduced rates of taxation, provided that certain holding period requirements and other conditions are satisfied. For these purposes, a non-U.S. corporation will be treated as a qualified foreign corporation with respect to dividends paid by that corporation on shares that are readily tradable on an established securities market in the United States. U.S. Treasury guidance indicates that shares listed on the NYSE (which the Trinseo PLC shares are expected to be) will be considered readily tradable on an established securities market in the United States. There can be no assurance that Trinseo PLC shares will be considered readily tradable on an established securities market in future years. Trinseo PLC will not

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constitute a qualified foreign corporation for purposes of these rules if it is a passive foreign investment company, or "PFIC," for the taxable year in which it pays a dividend or for the preceding taxable year. For further details, see the discussion below under "—Passive Foreign Investment Company Status."

The amount of any dividend paid in foreign currency will be the U.S. dollar value of the foreign currency distributed by Trinseo PLC, calculated by reference to the exchange rate in effect on the date the dividend is includible in the U.S. Holder's income, regardless of whether the payment is in fact converted into U.S. dollars on the date of receipt. Generally, a U.S. Holder should not recognize any foreign currency gain or loss if the foreign currency is converted into U.S. dollars on the date the payment is received. However, any gain or loss resulting from currency exchange fluctuations during the period from the date the U.S. Holder includes the dividend payment in income to the date such U.S. Holder actually converts the payment into U.S. dollars will be treated as ordinary income or loss. That currency exchange income or loss (if any) generally will be income or loss from U.S. sources for foreign tax credit limitation purposes.

To the extent that the amount of any distribution made by Trinseo PLC on Trinseo PLC shares exceeds Trinseo PLC's current and accumulated earnings and profits for a taxable year (as determined under U.S. federal income tax principles), the distribution will first be treated as a tax-free return of capital, causing a reduction in the adjusted basis of the U.S. Holder's Trinseo PLC shares, and to the extent the amount of the distribution exceeds the U.S. Holder's tax basis, the excess will be taxed as capital gain recognized on a sale or exchange as described below under "—Sale, Exchange, Redemption or Other Taxable Disposition of Trinseo PLC shares."

It is possible that Trinseo PLC is, or at some future time will be, at least 50% owned by U.S. persons. Dividends paid by a foreign corporation that is at least 50% owned by U.S. persons may be treated as U.S. source income (rather than foreign source income) for foreign tax credit purposes to the extent the foreign corporation has more than an insignificant amount of U.S. source income. The effect of this rule may be to treat a portion of any dividends paid by Trinseo PLC as U.S. source income. Treatment of the dividends as U.S. source income in whole or in part may limit a U.S. holder's ability to claim a foreign tax credit with respect to foreign taxes payable or deemed paid in respect of the dividends paid by Trinseo PLC or on other items of foreign source, passive income for U.S. federal foreign tax credit limitation purposes.

Sale, Exchange, Redemption or Other Taxable Disposition of Trinseo PLC shares

Subject to the discussion below under "—Passive Foreign Investment Company Status," a U.S. Holder generally will recognize gain or loss on any sale, exchange, redemption, or other taxable disposition of Trinseo PLC shares in an amount equal to the difference between the amount realized on the disposition and such U.S. Holder's adjusted tax basis in such Trinseo PLC shares. Any gain or loss recognized by a U.S. Holder on a taxable disposition of Trinseo PLC shares generally will be capital gain or loss and will be long-term capital gain or loss if the Trinseo PLC shareholder's holding period in such Trinseo PLC shares exceeds one year at the time of the disposition. Preferential tax rates may apply to long-term capital gains of non-corporate U.S. Holders (including individuals). The deductibility of capital losses is subject to limitations. Any gain or loss recognized by a U.S. Holder on the sale or exchange of Trinseo PLC shares generally will be treated as a U.S. source gain or loss.

Passive Foreign Investment Company Status ("PFIC")

Notwithstanding the foregoing, certain adverse U.S. federal income tax consequences could apply to a U.S. Holder if Trinseo PLC is treated as a PFIC for any taxable year during which such U.S. Holder holds Trinseo PLC shares. A non-U.S. corporation, such as Trinseo PLC, will be classified as a PFIC for U.S. federal income tax purposes for any taxable year in which, after the application of certain look-through rules, either (i) 75% or more of its gross income for such year is "passive income" (as defined in the relevant provisions of the Code) or (ii) 50% or more of the value of its assets (determined on the basis of a quarterly average) during such year consists of assets which produce or are held for the production of passive income. Passive income generally includes dividends, interest, royalties, rents, annuities, net gains from the sale or exchange of property producing such income and net foreign currency gains.

Trinseo PLC is not currently expected to be treated as a PFIC for U.S. federal income tax purposes, but this conclusion is a factual determination made annually and, thus, is subject to change. With certain exceptions, Trinseo PLC shares would be treated as stock in a PFIC with respect to a U.S. Holder if Trinseo PLC were a PFIC at any time during that U.S. Holder's holding period in such U.S. Holder's Trinseo PLC shares. There can be no assurance that Trinseo PLC will not be treated as a PFIC for any taxable year or at any time during a U.S. Holder's holding period.

If Trinseo PLC were to be treated as a PFIC, unless a U.S. Holder elects to be taxed annually on a mark-to-market basis with respect to its Trinseo PLC shares or the U.S. Holder makes an effective qualified electing fund election, gain realized on any sale or exchange of such Trinseo PLC shares and certain distributions received with respect to such Trinseo PLC shares could be subject to additional U.S. federal income taxes, plus an interest charge on certain taxes treated as having been deferred under the PFIC rules. In addition, dividends received with respect to Trinseo PLC shares would not constitute qualified dividend income eligible for preferential tax rates if Trinseo PLC is treated as a PFIC for the taxable year of the distribution or for its preceding taxable year. If a U.S. Holder makes an effective qualified electing fund election, or QEF Election, the U.S. Holder will be required to include in gross income each year, whether or not we make distributions, as capital gains, such U.S. Holder's pro rata share of Trinseo PLC's net capital gains and, as ordinary income, such U.S. Holder's pro rata share of our earnings in excess of Trinseo PLC's net capital gains. We do not currently intend to

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provide the information necessary for U.S. holders to make QEF Elections if we are treated as a PFIC for any taxable year. U.S. Holders should consult their own tax advisors regarding the application of the PFIC rules to their investment in Trinseo PLC shares.

Information Reporting and Backup Withholding

U.S. Holders that own at least five percent of the Trinseo S.A. shares (by vote or value) or Trinseo S.A. shares with a tax basis of $1,000,000 or more immediately before the Merger will be required to file certain Section 368(a) reorganization statements. Trinseo S.A. shareholders should consult their tax advisors about the other information reporting requirements that could be applicable to the exchange of Trinseo S.A. shares for Trinseo PLC shares in the Merger.

In general, information reporting requirements will apply to dividends received by U.S. Holders of Trinseo PLC shares, and the proceeds received on the disposition of Trinseo PLC shares effected within the United States (and, in certain cases, outside the United States), in each case, other than U.S. Holders that are exempt recipients (such as corporations). Backup withholding (currently at a rate of 24%) may apply to such amounts if the U.S. Holder fails to provide an accurate taxpayer identification number (generally on an IRS Form W-9 provided to the paying agent or the U.S. Holder's broker) or is otherwise subject to backup withholding.

Certain U.S. Holders holding specified foreign financial assets with an aggregate value in excess of the applicable dollar threshold are required to report information to the IRS relating to Trinseo PLC shares, subject to certain exceptions (including an exception for Trinseo PLC shares held in accounts maintained by U.S. financial institutions), by attaching a complete IRS Form 8938, Statement of Specified Foreign Financial Assets, with their tax return, for each year in which they hold Trinseo PLC shares. Such U.S. Holders should consult their own tax advisors regarding information reporting requirements relating to their ownership of Trinseo PLC shares.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or credit against a holder's U.S. federal income tax liability, if any, provided the required information is timely furnished to the IRS.

Material Irish Tax Considerations

Irish Tax Considerations

The following is a summary of the material Irish tax consequences of the Merger for certain beneficial owners of Trinseo S.A. shares in connection with the Merger, including the ownership and disposal of Trinseo PLC shares received by such holders pursuant to the Merger. This discussion is based on Irish tax laws and the practice of the Irish Revenue Commissioners in effect on the date of this Proxy Statement, all of which are subject to differing interpretations or change, possibly with retroactive effect. This summary does not purport to be a complete analysis or listing of all potential Irish tax considerations that may apply to a holder as a result of the Merger or as a result of the ownership and disposition of Trinseo PLC shares by a holder. In addition, this discussion does not address all aspects of Irish taxation that may be relevant to particular holders nor does it take into account the individual facts and circumstances of any particular holder that may affect the Irish tax consequences to such holder. Accordingly, this summary is not intended to be, and should not be construed as, tax advice. This discussion does not address Irish pay related social insurance, nor does it address any tax consequences specific to stock options, free shares or warrants. The summary is not exhaustive, and Trinseo S.A. shareholders should consult their tax advisors about the Irish tax consequences (and tax consequences under the laws of other relevant jurisdictions) of the transactions and of the acquisition, ownership and disposal of Trinseo PLC shares.

There can be no assurance that the Irish tax authorities will not challenge the Irish tax treatment described below or that, if challenged, such treatment will be sustained by a court.

The summary applies only to Trinseo S.A. shareholders who will own Trinseo PLC shares as capital assets and does not apply to other categories of Trinseo S.A. shareholders, such as dealers in securities, trustees, insurance companies, collective investment schemes, pension funds and Trinseo S.A. shareholders who have, or who are deemed to have, acquired their Trinseo PLC shares by virtue of an Irish office or employment (performed or carried on in Ireland).

Irish Capital Gains Tax ("CGT")

The rate of tax on chargeable gains (where applicable) in Ireland is 33%.

Non-resident Trinseo PLC shareholders

Trinseo PLC shareholders who are neither resident nor ordinarily resident in Ireland for Irish tax purposes and do not hold their Trinseo PLC shares in connection with a trade carried on by such Trinseo PLC shareholders through an Irish branch or agency will not be liable for Irish tax on chargeable gains realized on a subsequent disposal of their Trinseo PLC shares.

Trinseo S.A. shareholders who are neither resident nor ordinarily resident in Ireland for Irish tax purposes and do not hold their Trinseo S.A. shares in connection with a trade carried on by such Trinseo S.A. shareholders through an Irish branch or agency will not

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be liable for Irish tax on chargeable gains on the cancellation of their Trinseo S.A. shares, or on receipt of Trinseo PLC shares pursuant to the Merger.

Irish resident Trinseo PLC shareholders

The receipt by a Trinseo S.A. shareholder who is either resident or ordinarily resident in Ireland for Irish tax purposes or who holds their Trinseo S.A. shares in connection with a trade carried on in Ireland through a branch or agency of Trinseo PLC shares pursuant to the Merger will generally have the following consequences for such Trinseo S.A. shareholders.

The receipt of Trinseo PLC shares should be treated as a reconstruction for the purposes of Irish CGT. Accordingly, such Trinseo S.A. shareholders should not be treated as having made a disposal of their Trinseo S.A. shares for the purposes of Irish CGT to the extent that they receive Trinseo PLC shares. Instead, Trinseo PLC shares should be treated as the same asset as Trinseo S.A. shares in respect of which they are issued and treated as acquired at the same time and for the same acquisition cost as those Trinseo S.A. shares for Irish tax purposes. A chargeable gain or allowable loss should therefore only arise on a subsequent disposal of Trinseo PLC shares.

A subsequent disposal of Trinseo PLC shares by a Trinseo PLC shareholder who is resident or ordinarily resident in Ireland for Irish tax purposes or who holds his, her or its Trinseo PLC shares in connection with a trade carried on by such person through an Irish branch or agency will, subject to the availability of any exemptions and reliefs, generally be within the charge to Irish CGT.

A Trinseo PLC shareholder who is an individual and who is temporarily not resident in Ireland may, under Irish anti-avoidance legislation, still be liable to Irish tax on any chargeable gain realized upon a subsequent disposal of Trinseo PLC shares during the period in which such individual is a non-resident.

Stamp Duty

The rate of stamp duty (where applicable) on transfers of shares of Irish incorporated companies is 1% of the price paid or the market value of the shares acquired, whichever is greater. Where Irish stamp duty arises, it is generally a liability of the transferee.

No stamp duty will be payable on the Merger. Irish stamp duty may, depending upon the manner in which Trinseo PLC shares are held, be payable in respect of transfers of Trinseo PLC shares after the Merger.

Shares held through DTC

A transfer of Trinseo PLC shares effected by means of a transfer of book-entry interests in Trinseo PLC shares within the facilities of DTC will not be subject to Irish stamp duty, subject to confirmation from the Irish Revenue Commissioners in advance of the Merger.

Shares Held Directly and Shares Held Outside of DTC or Transferred Into or Out of DTC

A transfer of Trinseo PLC shares where any party to the transfer holds such shares directly (i.e., outside of DTC) may be subject to Irish stamp duty. Shareholders wishing to transfer their shares into (or out of) DTC may do so provided that:

    there is no change in the beneficial ownership of such shares as a result of the transfer; and

    the transfer into (or out of) DTC is not effected in contemplation of a sale of such shares by a beneficial owner to a third party.

Due to the potential Irish stamp charge on transfers of Trinseo PLC shares, it is strongly recommended that those Trinseo S.A. shareholders who do not hold their Trinseo S.A. shares through DTC should arrange for the transfer of their Trinseo S.A. shares into DTC as soon as possible and before the Merger is effected. It is also strongly recommended that any person who wishes to acquire Trinseo PLC shares after the Effective Date of the Merger acquires such Trinseo PLC shares through DTC.

Withholding Tax on Dividends

Distributions made by Trinseo PLC will, in the absence of one of many exemptions, be subject to Irish DWT currently at a rate of 20%.

For DWT purposes, a distribution includes any distribution that may be made by Trinseo PLC to Trinseo PLC shareholders, including cash dividends, non-cash dividends and additional stock taken in lieu of a cash dividend. Where an exemption does not apply in respect of a distribution made to a particular Trinseo PLC shareholder, Trinseo PLC is responsible for withholding DWT prior to making such distribution.

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General Exemptions

Irish domestic law provides that a non-Irish resident Trinseo PLC shareholder is not subject to DWT on dividends received from Trinseo PLC if such Trinseo PLC shareholder is beneficially entitled to the dividend and is either:

    a person (not being a company) resident for tax purposes in a "relevant territory" (including the U.S.) and is neither resident nor ordinarily resident in Ireland (for a list of "relevant territories" for DWT purposes, please see Annex C to this Proxy Statement);

    a company resident for tax purposes in a "relevant territory," provided such company is not under the control, whether directly or indirectly, of a person or persons who is or are resident in Ireland;

    a company, wherever resident, that is controlled, directly or indirectly, by persons resident in a "relevant territory" and who is or are (as the case may be) not controlled by, directly or indirectly, persons who are not resident in a "relevant territory";

    a company, wherever resident, whose principal class of shares (or those of its 75% direct or indirect parent) is substantially and regularly traded on a stock exchange in Ireland, on a recognized stock exchange in a "relevant territory" or on such other stock exchange approved by the Irish Minister for Finance; or

    a company, wherever resident, that is wholly owned, directly or indirectly, by two or more companies where the principal class of shares of each of such companies is substantially and regularly traded on a stock exchange in Ireland, on a recognized stock exchange in a "relevant territory" or on such other stock exchange approved by the Irish Minister for Finance;

and provided, in all cases noted above Trinseo PLC or, in respect of Trinseo PLC shares held through DTC, any qualifying intermediary appointed by Trinseo PLC, has received from the Trinseo PLC shareholder, where required, the relevant Irish Revenue Commissioners DWT forms (the "DWT Forms") prior to the payment of the dividend. In practice, in order to ensure sufficient time to process the receipt of relevant DWT Forms, the Trinseo PLC shareholder where required should furnish the relevant DWT Forms to:

    its broker (and the relevant information is further transmitted to any qualifying intermediary appointed by Trinseo PLC) before the record date for the dividend (or such later date before the dividend payment date as may be notified to the shareholder by the broker) if the Trinseo PLC shareholder holds Trinseo PLC shares through DTC; or

    Trinseo PLC transfer agent at least seven business days before the record date for the dividend if Trinseo PLC shares are held directly.

Links to the various DWT Forms are available at: http://www.revenue.ie/en/tax/dwt/forms/index.html

The information on such website does not constitute a part of, and is not incorporated by reference into, this Proxy Statement.

Such forms are generally valid, subject to a change in circumstances, until December 31 of the fifth year after the year in which such forms were completed.

For non-Irish resident Trinseo PLC shareholders who cannot avail themselves of one of Ireland's domestic law exemptions from DWT, it may be possible for such Trinseo PLC shareholders to rely on the provisions of a double tax treaty to which Ireland is party to reduce the rate of DWT.

Trinseo PLC shares Held by Residents of "Relevant Territories"

Trinseo PLC shareholders who are residents of "relevant territories," must satisfy the conditions of one of the exemptions referred to above under the heading "—General Exemptions", including the requirement to furnish valid DWT forms, in order to receive dividends without suffering DWT. If such Trinseo PLC shareholders hold their Trinseo PLC shares through DTC, they must provide the appropriate DWT forms to their brokers (so that such brokers can further transmit the relevant information to a qualifying intermediary appointed by Trinseo PLC) before the record date for the dividend (or such later date before the dividend payment date as may be notified to the Trinseo PLC shareholder by the broker). If such Trinseo PLC shareholders hold their Trinseo PLC shares directly, they must provide the appropriate DWT forms to Trinseo PLC's transfer agent at least seven business days before the record date for the dividend. It is strongly recommended that such Trinseo PLC shareholders complete the appropriate DWT Forms and provide them to their brokers or Trinseo PLC's transfer agent, as the case may be, as soon as possible after receiving their Trinseo PLC shares.

If any Trinseo PLC shareholder who is resident in a "relevant territory" receives a dividend from which DWT has been withheld, the Trinseo PLC shareholder may be entitled to a refund of DWT from the Irish Revenue Commissioners provided the Trinseo PLC shareholder is beneficially entitled to the dividend.

Trinseo PLC shares Held by Residents of Ireland

Most Irish tax resident or ordinarily resident Trinseo PLC shareholders (other than Irish resident companies that have completed the appropriate DWT forms) will be subject to DWT in respect of dividends paid on their Trinseo PLC shares.

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Shareholders that are residents of Ireland, but are entitled to receive dividends without DWT, must complete the appropriate DWT Forms and provide them to their brokers (so that such brokers can further transmit the relevant information to a qualifying intermediary appointed by Trinseo PLC) before the record date for the dividend (or such later date before the dividend payment date as may be notified to the Trinseo PLC shareholder by the broker) (in the case of Trinseo PLC shares held through DTC), or to Trinseo PLC's transfer agent at least seven business days before the record date for the dividend (in the case of Trinseo PLC shares held directly).

Trinseo PLC shares Held by Other Persons

Trinseo PLC shareholders that do not fall within any of the categories specifically referred to above may nonetheless fall within other exemptions from DWT. If any Trinseo PLC shareholders are exempt from DWT, but receive dividends subject to DWT, such Trinseo PLC shareholders may apply for refunds of such DWT from the Irish Revenue Commissioners.

Trinseo PLC will rely on information received directly or indirectly from brokers and its transfer agent in determining where Trinseo PLC shareholders reside, whether they have provided the required DWT Forms.

Income Tax on Dividends Paid on Trinseo PLC shares

Irish income tax may arise for certain persons in respect of dividends received from Irish resident companies.

A Trinseo PLC shareholder that is not resident or ordinarily resident in Ireland and that is entitled to an exemption from DWT generally has no liability to Irish Income Tax or the universal social charge on a dividend from Trinseo PLC. An exception to this position may apply where such Trinseo PLC shareholder holds Trinseo PLC shares through a branch or agency in Ireland through which a trade is carried on.

A Trinseo PLC shareholder that is not resident or ordinarily resident in Ireland and that is not entitled to an exemption from DWT generally has no additional liability to Irish income tax or the universal social charge. An exception to this position may apply where the Trinseo PLC shareholder holds Trinseo PLC shares through a branch or agency in Ireland through which a trade is carried. The DWT deducted by Trinseo PLC discharges the liability to Irish income tax.

Irish resident or ordinarily resident Trinseo PLC shareholders may be subject to Irish tax and/or the universal social charge on dividends received from Trinseo PLC. Credit should be available against this Irish tax for any DWT declared by Trinseo PLC. Such Trinseo PLC shareholders should consult their own tax advisors.

Withholding Tax on Share Repurchases

It is anticipated that Irish DWT should not generally apply to payments made by Trinseo PLC on the redemption or repurchase of its own shares. This is because an Irish tax resident company that is a quoted company is not treated as making a distribution for Irish tax purposes on making payments to redeem, repay or repurchase its own shares, provided the redemption or repurchase does not form part of a scheme or arrangement the main purpose (or one of the main purposes of which) is to enable shareholders to participate in the profits of the company without receiving a dividend.

Capital Acquisitions Tax

Irish capital acquisitions tax ("CAT") is comprised of principally gift tax and inheritance tax. CAT could apply to a gift or inheritance of Trinseo PLC shares irrespective of the place of residence, ordinary residence or domicile of the parties. This is because Trinseo PLC shares are regarded as property situated in Ireland as the share register of Trinseo PLC must be held in Ireland. The person who receives the gift or inheritance has primary liability for CAT.

CAT is currently levied at a rate of 33% above certain tax-free thresholds. The appropriate tax-free threshold is dependent upon (i) the relationship between the donor and the donee and (ii) the aggregation of the values of previous gifts and inheritances received by the donee from persons within the same group threshold. Gifts and inheritances passing between spouses are exempt from CAT. Trinseo PLC shareholders should consult their own tax advisors as to whether CAT is creditable or deductible in computing any domestic tax liabilities.

Material Luxembourg Tax Considerations

The information set out below is a general summary of certain material Luxembourg tax consequences in connection with the Merger. This summary is not a comprehensive or complete description of all the Luxembourg tax considerations that may be relevant for a particular Trinseo S.A. shareholder and it does not address the tax consequences that may arise in any jurisdiction other than Luxembourg in connection with the Merger. For Luxembourg tax purposes, a Trinseo S.A. shareholder may include an individual who or an entity that does not have the legal title to the Trinseo S.A. shares, but to whom nevertheless Trinseo S.A. shares, or the income thereof, are attributed based either on such individual or entity holding a beneficial interest in Trinseo S.A. shares or based on specific statutory provisions.

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This summary is based on the tax laws of Luxembourg as in effect on the date of this Proxy Statement, including regulations, rulings and decisions of Luxembourg and its taxing and other authorities available in printed form on or before this date and now in effect, and as applied and interpreted by Luxembourg courts, without prejudice to any developments or amendments introduced at a later date and implemented with or without retroactive effect.

Any reference in this summary to Luxembourg or Luxembourg tax law are to the European part of the Grand Duchy of Luxembourg and its law, respectively, only.

As this summary is intended as general information only, Trinseo S.A. shareholders should consult their own tax advisors as to the Luxembourg or other tax consequences of the Merger, including the application to their particular situations of the tax considerations discussed below.

This summary does not address the tax consequences for any Trinseo S.A. shareholder:

    who is an individual and for whom the income or capital gains derived from Trinseo S.A. shares are attributable to employment activities, the income from which is taxable in Luxembourg;

    who has, or that has, a substantial shareholding (more than 10% in the share capital in Trinseo S.A. the Luxembourg Income Tax Law (Loi modifiée du 4 Décembre 1967 concernant l'impôt sur le revenue, "LITL");

    that is an entity that is resident or deemed to be resident in Luxembourg and that is, in whole or in part, not subject to or exempt from Luxembourg corporate income tax (such as qualifying pension funds);

    that is an entity for which the income and/or capital gains derived from the Trinseo S.A. shares are exempt under the participation exemption as set out in LITL;

    that is an exempt Undertaking for Collective Investment in Transferable Securities (UCITS) governed by the Luxembourg Law of 17 December 2010 or Alternative Investment Funds (AIFs) within the meaning of the Luxembourg Law of 12 July 2013;

    who is, or that is, not considered the beneficial owner of Trinseo S.A. shares and/or the income and/or capital gains derived from Trinseo S.A. shares.

Taxation of Exchange of Trinseo S.A. shares for Trinseo PLC shares pursuant to the Merger

Luxembourg Resident Trinseo S.A. Shareholders

A Trinseo S.A. shareholder who is resident or deemed to be resident in Luxembourg for purposes of Luxembourg taxation (a "Luxembourg Resident"), may be subject to Luxembourg corporate income tax and Luxembourg municipal business tax in respect of the exchange of Trinseo S.A. shares for Trinseo PLC shares pursuant to the Merger, depending on the tax regime applicable to such holder.

Non-Luxembourg Resident Trinseo S.A. Shareholders

A Trinseo S.A. shareholder who is not, nor deemed to be, a Luxembourg Resident, (a "Non-Luxembourg Resident") is generally not subject to Luxembourg income tax or Luxembourg corporate income tax (as applicable) in respect of the exchange of Trinseo S.A. shares for Trinseo PLC shares pursuant to the Merger, provided that:

    in case of a Non-Luxembourg Resident that is an entity, such entity has held a shareholding representing more than 10% in the share capital of Trinseo S.A. for more than six months from the acquisition of the shareholding;

    in case of a Non-Luxembourg Resident that is an entity, which holds a substantial shareholding of more than 10% for less than six months, such entity is a qualified tax resident in a jurisdiction with which Luxembourg has concluded a double tax treaty under which the right to tax gains from the alienation of movable property is attributable to the State of which the alienator is a resident;

    such Non-Luxembourg Resident does not derive profits from an enterprise or deemed enterprise, whether as an entrepreneur or pursuant to a co-entitlement to the net worth of such enterprise (other than as an entrepreneur or a shareholder) which enterprise is, in whole or in part, carried on through a permanent establishment in Luxembourg and to which enterprise or part of an enterprise, as the case may be, the Trinseo S.A. shares are attributable or deemed attributable;

    in case of a Non-Luxembourg Resident who is an individual, such individual does not derive income or capital gains from Trinseo S.A. shares, as the case may be, that are taxable as benefits from 'miscellaneous activities performed in Luxembourg', which include the performance of activities in respect of Trinseo S.A. shares, that exceed regular, active portfolio management and also includes benefits resulting from a lucrative interest;

    in case of a Non-Luxembourg Resident who is an individual, such individual is not entitled to a share in the profits of an enterprise effectively managed in Luxembourg, other than by way of the holding of securities or through an employment relationship, to which enterprise Trinseo S.A. shares or payments in respect of Trinseo S.A. shares are attributable; and

    in case of a Non-Luxembourg Resident that is an entity, such entity is neither entitled to a share in the profits of an enterprise nor co-entitled to the net worth of an enterprise effectively managed in Luxembourg, other than by way of the holding of securities, to which enterprise Trinseo S.A. shares or payments in respect of Trinseo S.A. shares are attributable.

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DESCRIPTION OF TRINSEO PLC SHARES

Description of Trinseo PLC Shares

The following description of the share capital of Trinseo PLC, including the Trinseo PLC ordinary shares to be issued in the Merger, is a summary. This summary does not purport to be complete and, along with the other statements in this section, is qualified in its entirety by reference to, and is subject to, the complete text of the Proposed Constitution that will be in effect on completion of the Merger, which will be substantially in the form filed as Annex B to this Proxy Statement. You are urged to read the Proposed Constitution and relevant provisions of the Irish Companies Act for a more complete understanding of the rights conferred by Trinseo PLC shares. The following summary is not a description of the Proposed Constitution currently in effect.

There are differences between our Articles and the Proposed Constitution. Certain provisions of Trinseo S.A.'s current Articles will not be replicated in the Proposed Constitution, and certain provisions that will be included in the Proposed Constitution are not in Trinseo S.A.'s current Articles. For further detail, see the section captioned "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution" in Proposal 3, beginning on page 40.

Except where otherwise indicated, the description below reflects the Proposed Constitution as such document will be in effect as of the Effective Date.

Capital Structure

The rights of and restrictions applicable to the share capital of Trinseo PLC are prescribed in the Proposed Constitution, subject to the Irish Companies Act.

Authorized Share Capital

Trinseo PLC has an authorized share capital of US$50,000,000 and €25,000, comprised of 4,000,000,000 ordinary shares of US$0.01 each, 1,000,000,000 preferred shares of €0.01 each, and 25,000 deferred ordinary shares of €1.00 each.

The authorized share capital includes 25,000 deferred ordinary shares of €1.00 each, which were created solely to satisfy minimum statutory capital requirements that apply to all Irish public limited companies. The holders of the deferred ordinary shares are not entitled to receive any dividend or distribution, to attend, speak or vote at any general meeting, and effectively have no rights to participate in the assets of Trinseo PLC on a winding-up.

Immediately following completion of the Merger, Trinseo PLC will have an issued share capital comprising such number of Trinseo PLC ordinary shares as will be equal to the number of Trinseo S.A. ordinary shares issued immediately prior to completion of the Merger (excluding any treasury shares held by Trinseo S.A.), together with the 25,000 deferred ordinary shares. Each Trinseo PLC ordinary share will be entitled to one vote.

Under the Proposed Constitution, Trinseo PLC may issue new shares in Trinseo PLC up to its maximum authorized share capital. The authorized share capital may be increased or reduced by a resolution approved by a simple majority of the votes cast at a general meeting of shareholders of Trinseo PLC, referred to under Irish law as an "ordinary resolution".

Under Irish law, the directors of a company may issue new ordinary or preferred shares without shareholder approval once authorized to do so by the constitution or by an ordinary resolution adopted by the shareholders at a general meeting. The authorization may be granted for a maximum period of five years, at which point it must be renewed by the shareholders by an ordinary resolution. The Proposed Constitution authorizes the Trinseo PLC Board to allot shares in Trinseo PLC with an aggregate par value amount up to the maximum of its authorized but unissued share capital as at the date of adoption of the Proposed Constitution without approval from shareholders for a period of five years from the date of adoption of the Proposed Constitution.

Under the Proposed Constitution, the Trinseo PLC Board will be authorized to issue preferred shares with discretion as to the terms attaching to the preferred shares, including as to voting, dividend and conversion rights and priority relative to other classes of shares with respect to dividends and upon a liquidation. As described in the preceding paragraph, the authority to issue new shares in Trinseo PLC extends until five years from the date of the adoption of the Proposed Constitution, at which time it will expire unless renewed by Trinseo PLC's shareholders.

Notwithstanding this authority, under the Irish Takeover Rules (as defined below) the Trinseo PLC Board would not be permitted to issue any shares in Trinseo PLC, including ordinary or preferred shares, during a period when an offer has been made for Trinseo PLC or is believed to be imminent unless the issue falls within one of the exceptions described in the section below captioned "—Anti-Takeover Measures—Frustrating Action".

While Trinseo PLC does not have any current specific plans, arrangements or understandings, written or oral, to issue any preferred shares for any purpose, we are continually evaluating our financial position and analyzing the possible benefits of issuing additional debt securities, equity securities, convertible securities or a combination thereof in connection with, among other things: (i) repaying indebtedness; (ii) financing acquisitions; or (iii) strengthening our balance sheet. The availability of preferred shares gives us flexibility to

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respond to future capital raising, financing and acquisition needs and opportunities without the delay and expense associated with holding an extraordinary general meeting of Trinseo PLC's shareholders to obtain further approval.

Irish law does not recognize fractional shares held of record. Accordingly, the Proposed Constitution does not provide for the issuance of fractional shares, and our official Irish share register will not reflect any fractional shares.

Issued Share Capital

The Merger will result in each Trinseo S.A. ordinary share being cancelled and an equivalent number of Trinseo PLC ordinary shares being issued to the former Trinseo S.A. shareholders on a one-for-one basis.

In addition, 25,000 Trinseo PLC deferred ordinary shares will be held by MSFD Nominees Limited, to meet the Irish statutory minimum capital requirements of an Irish public limited company. The deferred ordinary shares will remain outstanding following the completion of the Merger and will continue to be held thereafter by MSFD Nominees Limited until redeemed at par or surrendered. These Trinseo PLC deferred ordinary shares (i) will not have any voting rights; (ii) will not entitle the holders thereof to any dividends or other distributions of Trinseo PLC; and (iii) will not entitle the holders thereof to participate in the surplus assets of Trinseo PLC on a winding-up beyond, in total, the nominal value of such Trinseo PLC deferred ordinary shares held (subject to the prior repayment of the amount paid-up on each of the Trinseo PLC shares plus an additional amount of $5,000,000 in cash per Trinseo PLC ordinary share). Accordingly, these Trinseo PLC deferred ordinary shares will not dilute the economic ownership of Trinseo PLC shareholders.

Under the Proposed Constitution, subject to the Irish Companies Act, the Trinseo PLC Board (or an authorized committee of the Trinseo PLC Board) is authorized to approve the allotment, issue, grant and disposal of, or otherwise deal with, shares, options, equity awards, rights over shares, warrants, other securities and derivatives (including unissued shares) in or of Trinseo PLC to such persons, at such times and on such terms as it thinks fit (including specifying the conditions of allotment of shares for the purposes of the Irish Companies Act).

Preemptive Rights

Under Irish law, certain statutory preemption rights apply automatically in favor of shareholders where shares are to be issued for cash. As permitted by Irish law, Trinseo PLC has opted to disapply these preemption rights in the Proposed Constitution, such that the Trinseo PLC Board will be authorized to allot shares of any class in Trinseo PLC with an aggregate par value amount up to the maximum of its authorized but unissued share capital as at the date of adoption of the Proposed Constitution without approval from Trinseo PLC's shareholders for a period of five years from the date of adoption of the Proposed Constitution.

Irish law requires this disapplication to be renewed at least every five years by 75% of the votes cast at a general meeting of shareholders, referred to under Irish law as a "special resolution". If the disapplication is not renewed, new equity shares in Trinseo PLC issued for cash must be offered to existing shareholders of Trinseo PLC on a pro rata basis to their existing shareholdings before the shares may be issued to any new shareholders.

Statutory preemption rights do not apply (i) where shares are issued for non-cash consideration (such as in a share-for-share acquisition); (ii) to the issue of non-equity shares (that is, shares that have the right to participate only up to a specified amount in any income or capital distribution); or (iii) where shares are issued pursuant to an employee stock option or similar equity plan.

Dividends

Under Irish law, Trinseo PLC will be able to declare dividends and make distributions only out of "distributable profits". Distributable profits are the accumulated realized profits of Trinseo PLC that have not previously been utilized in a distribution or capitalization less accumulated realized losses that have not previously been written off in a reduction or reorganization of capital, and include reserves created by way of a reduction of capital. In addition, no distribution or dividend may be paid or made by Trinseo PLC unless the net assets of Trinseo PLC are equal to, or exceed, the aggregate of Trinseo PLC's called-up share capital plus its undistributable reserves and the distribution does not reduce Trinseo PLC's net assets below such aggregate. Undistributable reserves include the undenominated capital, the capital redemption reserve fund and the amount by which Trinseo PLC's accumulated unrealized profits that have not previously been utilized by any capitalization exceed Trinseo PLC's accumulated unrealized losses that have not previously been written off in a reduction or reorganization of capital.

The determination as to whether Trinseo PLC has sufficient distributable profits to fund a dividend must be made by reference to its "relevant financial statements". The "relevant financial statements" will be either the last set of unconsolidated annual audited financial statements or other financial statements properly prepared in accordance with the Irish Companies Act, which give a "true and fair view" of Trinseo PLC's unconsolidated financial position and accord with accepted accounting practice and have been filed with the Irish Companies Registration Office.

The mechanism as to who declares a dividend and when a dividend becomes payable is governed by the Proposed Constitution. The Proposed Constitution authorizes the Trinseo PLC Board to declare interim dividends without approval from Trinseo PLC's shareholders if it considers that the financial position of Trinseo PLC justifies such payment. The Trinseo PLC Board may also

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recommend a dividend to be approved and declared by Trinseo PLC's shareholders at a general meeting. No dividend issued may exceed the amount recommended by the Trinseo PLC Board. The Proposed Constitution provides that dividends may be paid in cash, property or paid-up shares. Any cash payment may be made by check or warrant or sent by any electronic or other means of payment.

Except as otherwise provided by the rights attached to shares in Trinseo PLC, all shares in Trinseo PLC will carry a pro rata entitlement to the receipt of dividends. Unless provided for by the rights attached to shares in Trinseo PLC, no dividend or other monies payable by Trinseo PLC in respect of a share in Trinseo PLC shall bear interest.

If a dividend cannot be paid to a holder of shares in Trinseo PLC or otherwise remains unclaimed, the Trinseo PLC Board may pay it into a separate Trinseo PLC account and Trinseo PLC will not be a trustee in respect thereof. A dividend that remains unclaimed for a period of six years from the date of its declaration will be forfeited and will revert to Trinseo PLC.

Share Repurchases, Redemptions and Conversions

Repurchases and Redemptions

The Proposed Constitution provides that Trinseo PLC may purchase its own shares and redeem outstanding redeemable shares. Under the Irish law, shares can only be purchased or redeemed out of: (i) distributable profits; or (ii) the proceeds of a new issue of shares made for the purpose of the purchase or redemption.

Under the Irish Companies Act, a company may purchase its own shares either (i) "on-market" on a recognized stock exchange, which includes the NYSE; or (ii) "off-market" (i.e., otherwise than on a recognized stock exchange).

For Trinseo PLC to make "on-market" purchases of shares in Trinseo PLC, Trinseo PLC's shareholders must provide general authorization to Trinseo PLC to do so by way of an ordinary resolution. For so long as a general authority is in force, no additional shareholder authority for a particular "on-market" purchase is required. Such authority can be given for a maximum period of five years before it is required to be renewed and must specify: (i) the maximum number of shares that may be purchased; and (ii) the maximum and minimum prices that may be paid for the shares by specifying particular sums or providing a formula.

For an "off-market" purchase, the proposed purchase contract must be authorized by special resolution of the shareholders before the contract is entered into.

Separately, Trinseo PLC can redeem (as opposed to purchase) its redeemable shares once permitted to do so by the Proposed Constitution (without the requirement for additional shareholder authority). The Proposed Constitution provides that, unless the Trinseo PLC Board determines otherwise, any Trinseo PLC share that Trinseo PLC has agreed to acquire shall be automatically converted into a redeemable share. Accordingly, for purposes of the Irish Companies Act, unless the Trinseo PLC Board determines otherwise, the acquisition of Trinseo PLC shares by Trinseo PLC will technically be effected as a redemption of those Trinseo PLC shares. If the Proposed Constitution did not contain such provision, acquisitions of Trinseo PLC shares by Trinseo PLC would require to be effected as "on-market" or "off-market" purchases, as described above.

Repurchased and redeemed shares may be cancelled or held as treasury shares, provided that the par value of treasury shares held by Trinseo PLC at any time must not exceed 10% of the par value of Trinseo PLC's company capital (comprising the aggregate of all amounts of par value plus share premium paid for Trinseo PLC's shares plus certain other sums, which may be credited as such).

Trinseo PLC cannot exercise any rights in respect of any treasury shares. Treasury shares can either be held in treasury, re-issued "on-market" or "off-market" or cancelled. Depending on the circumstances of their acquisition, treasury shares may be held indefinitely or require to be cancelled after one or three years. The re-issue of treasury shares requires to be made pursuant to a valid and subsisting shareholder authority given by way of a special resolution.

Purchases by Subsidiaries

Under Irish law, a subsidiary of Trinseo PLC may purchase shares in Trinseo PLC either "on-market" or "off market," provided such purchases are authorized by Trinseo PLC's shareholders as outlined above. The redemption option is not available to a subsidiary of Trinseo PLC.

The number of shares in Trinseo PLC held by Trinseo PLC's subsidiaries at any time will count as treasury shares and will be included in any calculation of the 10% permitted treasury share threshold, as described above. While a subsidiary holds any of our shares, it cannot exercise voting rights in respect of those shares. The acquisition of our shares by a subsidiary must be funded out of distributable profits of the subsidiary.

Consolidation and Division; Subdivision

Under the Irish Companies Act, Trinseo PLC may, by ordinary resolution, consolidate and divide all or any of its share capital into shares of larger par value than its existing shares, or subdivide its shares into smaller amounts.

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Reduction of Share Capital

Trinseo PLC may reduce its share capital by way of a court approved procedure that also requires approval by special resolution of Trinseo PLC's shareholders at a general meeting.

Lien on Shares, Calls on Shares and Forfeiture of Shares

The Proposed Constitution provides that Trinseo PLC will have a first and paramount lien on every share that is not a fully paid-up share for an amount equal to the unpaid portion of such share. Subject to the terms of their allotment, directors may call for any unpaid amounts in respect of any shares in Trinseo PLC to be paid, and if payment is not made, the shares may be forfeited.

These provisions are customary in the constitution of an Irish public company limited by shares.

General Meetings of Shareholders

Trinseo PLC must hold its annual general meeting no more than nine months after its accounting year end (which is currently December 31).

In addition to any SEC mandated resolutions, the business of Trinseo PLC's annual general meeting is required to include: (a) the consideration of Trinseo PLC's statutory financial statements; (b) the review by shareholders of Trinseo PLC of Trinseo PLC's affairs; (c) the election and reelection of directors in accordance with the Proposed Constitution; (d) the appointment or reappointment of the Irish statutory auditors; (e) the authorization of the directors to approve the remuneration of the statutory auditors; and (f) the declaration of dividends (other than interim dividends).

The Proposed Constitution provides that the Trinseo PLC Board may convene general meetings of the Trinseo PLC's shareholders at any place they so designate. All general meetings, other than annual general meetings, are referred to as "extraordinary general meetings" at law.

If a general meeting is held outside Ireland, Trinseo PLC has a duty, at its expense, to make all necessary arrangements to ensure that Trinseo PLC's shareholders can by technological means participate in any such meeting without leaving Ireland.

The Proposed Constitution requires that notice of an annual general meeting of Trinseo PLC's shareholders must be delivered to the shareholders at least 21 clear days before the meeting. Shareholders must be notified of all general meetings (other than annual general meetings) at least 14 clear days prior to the meeting (provided that, in the case of an extraordinary general meeting for the passing of a special resolution, at least 21 clear days' notice is required). "Clear days" means calendar days and excludes (1) the date on which a notice is given, or a request received; and (2) the date of the meeting itself. The Company will continue to be bound by U.S. securities regulations governing notice & proxy statement delivery.

Calling Special Meetings of Shareholders

The Proposed Constitution provides that general meetings of shareholders may be called on the order of the Trinseo PLC board. Under Irish law, one or more shareholders representing at least 10% of the paid-up share capital of Trinseo PLC carrying voting rights have the right to requisition the holding of an extraordinary general meeting.

Serious Loss of Capital

If the directors of Trinseo PLC become aware that the assets of Trinseo PLC are half or less of the amount of Trinseo PLC's called-up share capital, the directors must convene an extraordinary general meeting of Trinseo PLC no later than 28 days after the earliest day on which that fact is known to a director (and the general meeting must be convened for a date not later than 56 days from that day). The meeting must be convened for the purpose of considering whether any, and if so what, measures should be taken to address the situation.

Quorum for Meetings of Shareholders

Under the Proposed Constitution, holders of at least a simple majority of the shares issued and entitled to vote at a general meeting constitute a quorum.

The necessary quorum at a separate general meeting of the holders of any class of shares is holders of at least a simple majority of that class of shares issued and entitled to vote.

Voting Rights

Under the Proposed Constitution, each Trinseo PLC shareholder is entitled to one vote for each Trinseo PLC share that they hold as of the record date for the meeting. A holder of the deferred ordinary shares is not entitled to a vote. No voting rights can be exercised in respect of any shares held as treasury shares, including shares held by subsidiaries.

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All resolutions at an annual general meeting or other general meeting will be decided on a poll.

On a poll every Trinseo PLC shareholder who is present, in person or by proxy, at the general meeting, is entitled to one vote for every Trinseo PLC share held by such Trinseo PLC shareholder.

On a separate general meeting of the holders of any class of shares, all votes will be taken on a poll and each holder of shares of the class will, on a poll, have one vote in respect of every share of that class held by such shareholder.

Under the Irish Companies Act and the Proposed Constitution, certain matters require "ordinary resolutions", which must be approved by at least a majority of the votes cast, in person or by proxy, by shareholders at a general meeting, and certain other matters require "special resolutions", which require the affirmative vote of at least 75% of the votes cast, in person or by proxy, by shareholders at a general meeting.

An ordinary resolution is needed (among other matters) to remove a director, provide, vary or renew the directors' authority to allot shares and to appoint directors (where appointment is by shareholders).

A special resolution is needed (among other matters) to: alter a company's constitution, exclude statutory preemptive rights on allotment of securities for cash (up to five years); reduce a company's share capital; re-register a public company as a private company (or vice versa); and approve a scheme of arrangement.

Cumulative voting is not recognized under Irish law.

Variation of Rights Attaching to a Class of Shares

Under the Proposed Constitution and the Irish Companies Act, any variation of class rights attaching to our issued shares must be approved by a special resolution of our shareholders of the affected class or with the consent in writing of the holders of three-quarters of all the votes of that class of shares.

Inspection of Books and Records

Generally, the register of Trinseo PLC's shareholders may be inspected during business hours (1) for free, by Trinseo PLC's shareholders; and (2) for a fee by any other person.

Documents may be copied for a fee.

The service contracts, if any, of Trinseo PLC's directors can be inspected by Trinseo PLC's shareholders without charge and during business hours. A "service contract" includes any contract under which such a director undertakes personally to provide services to the company or a subsidiary company, whether in that person's capacity as a director, an executive officer or otherwise. Service contracts with an unexpired term of less than three years are not required to be kept for inspection.

Trinseo PLC's shareholders have the right to receive a copy of the Proposed Constitution.

Trinseo PLC's shareholders may also inspect, without charge and during business hours, the minutes of meetings of the shareholders and obtain copies of the minutes for a fee.

In addition, the published annual statutory financial statements of Trinseo PLC are required to be available for Trinseo PLC's shareholders at a general meeting and a shareholder is entitled to a copy of these financial statements. Shareholders have a right to receive financial statements of subsidiaries that have previously been produced to an annual general meeting of such subsidiary in the preceding ten years. The auditors' report must be circulated to the Trinseo PLC's shareholders with the financial statements prepared in accordance with Irish law at least 21 days before the annual general meeting.

Under Irish law, the shareholders of a company do not have the right to inspect the corporate books of a subsidiary of that company.

Acquisitions

Shareholder Approval of Merger or Consolidation

Irish law recognizes the concept of a statutory merger in three situations: (1) a domestic merger where an Irish private limited company merges with another Irish company (not being a public limited company) under Part 9 of the Irish Companies Act; (2) a domestic merger where an Irish public limited company merges with another Irish company under Part 17 of the Irish Companies Act; and (3) a cross-border merger, where an Irish company merges with another company based in the European Economic Area ("EEA") under the European Communities (Cross-border Merger) Regulations 2008 of Ireland.

Under Irish law and subject to applicable U.S. securities laws and the NYSE's rules and regulations, where Trinseo PLC proposes to acquire another company, approval of Trinseo PLC's shareholders is not required, unless effected as a direct domestic merger or direct cross-border merger as referred to above.

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Under Irish law, where another company proposes to acquire Trinseo PLC, the requirement for the approval of Trinseo PLC's shareholders depends on the method of acquisition.

Schemes of Arrangement

Under Irish law, schemes of arrangement are arrangements or compromises between a company and any class of shareholders or creditors, and are used in certain types of reconstructions, amalgamations, capital reorganizations or takeovers (similar to a merger in the United States). Such arrangements require the approval of: (i) a majority in number of shareholders or creditors (as the case may be) representing 75% in value of the creditors or each class of creditors or shareholders or each class of shareholders present and voting either in person or by proxy at a special meeting convened by order of the court; and (ii) the Irish High Court.

Once approved by the requisite shareholder and creditor majority, sanctioned by the Irish High Court and becoming effective, all shareholders and/or, as the case may be, creditors of the relevant class are bound by the terms of the scheme. Dissenting shareholders and/or, as the case may be, creditors have the right to appear at the Irish High Court hearing and make representations in objection to the scheme.

Takeover Offer

The Irish Companies Act also provides that where (i) a takeover offer is made for shares, and (ii) following the offer, the offeror has acquired or contracted to acquire not less than 80% of the shares to which the offer relates, the offeror may require the other shareholders who did not accept the offer to transfer their shares on the terms of the offer.

A dissenting shareholder may object to the transfer on the basis that the offeror is not entitled to acquire its shares or to specify terms of acquisition different from those in the offer by applying to the court within 30 days of the date on which notice of the transfer was given. In the absence of fraud or oppression, and subject to strict compliance with the terms of the statute, the court is unlikely to order that the acquisition shall not take effect, but it may specify terms of the transfer that it finds appropriate.

A minority shareholder is also entitled in similar circumstances to require the offeror to acquire his or her shares on the terms of the offer.

Statutory Mergers

It is also possible for Trinseo PLC to be acquired by way of a domestic or cross-border statutory merger, as described above. Such mergers must be approved by a special resolution of shareholders. If the consideration being paid to shareholders is not all in the form of cash, dissenting shareholders may be entitled, in certain circumstances, to require that their shares be acquired for cash.

Related-Party Transactions

Trinseo PLC will be subject to the rules of the NYSE and the SEC regarding related-party transactions.

Under Irish law, certain transactions between Trinseo PLC and any director of Trinseo PLC are prohibited unless approved by Trinseo PLC's shareholders, such as loans, credit transactions and substantial property transactions. This prohibition extends to transactions with close personal relations and companies controlled by any such director.

Shareholder Suits

Under Irish law, the power to initiate a lawsuit on behalf of the company is generally a matter for its board of directors, and shareholders' rights to initiate a derivative lawsuit on behalf of the company are limited.

The central question at issue in deciding whether a shareholder may be entitled to bring a derivative action is whether, unless the action is brought, a wrong committed against the company would go unredressed.

The principal case law in Ireland indicates that to bring a derivative action, a person must first establish a prima facie case: (a) that the company is entitled to the relief claimed; and (b) that the action falls within one of the five exceptions derived from case law, as follows: (1) where an ultra vires or illegal act is perpetrated; (2) where more than a bare majority is required to ratify the "wrong" complained of; (3) where the shareholders' personal rights are infringed; (4) where a fraud has been perpetrated upon a minority by those in control; or (5) where the justice of the case requires.

While Irish law only permits a shareholder to bring a derivative action and initiate a lawsuit on behalf of the company in limited circumstances, it does permit a shareholder whose name is on the register of shareholders of a company to apply for a court order where the company's affairs are being conducted or the powers of the company's directors are being exercised: (1) in a manner oppressive to him or her or any of the shareholders; or (2) in disregard of his or her or their interests as shareholders.

Oppression connotes conduct that is burdensome, harsh and wrongful. Furthermore, the oppression or the disregard of interests must result from either the conduct of the affairs of the company or the exercise of the powers of the directors.

This is a statutory remedy and an Irish court has wide discretion to make such order as it sees fit.

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Lawsuits brought by a shareholder on behalf of the company must be brought exclusively in the courts of Ireland when they are related to or in connection with a derivative claim, an alleged breach of fiduciary or other duty by a director, officer or employee of Trinseo PLC or any other claim against Trinseo PLC or its directors, officers and employees under Irish law or pursuant to the constitution.

Disclosure of Interests in Shares

The Schedule 13D and Schedule 13G reporting regime will continue to apply to Trinseo PLC as it will have its shares registered under Section 12 of the Exchange Act.

Under the Irish Companies Act, a person must notify us if, as a result of a transaction, the person will become interested in three percent or more of our voting shares, or if as a result of a transaction a person who was interested in three percent or more of our voting shares ceases to be so interested. Under the Irish Companies Act, an "interest" is broadly defined and includes direct and indirect holdings, beneficial interests and, in some cases, derivative interests. Furthermore, a person's interests are aggregated with the interests of related persons and entities (including controlled companies). Where a person is interested in three percent or more of our voting shares, the person must notify us of any alteration of his or her interest that brings his or her total holding through the nearest whole percentage number, whether an increase or a reduction. The relevant percentage figure is calculated by reference to the aggregate nominal value of the voting shares in which the shareholder is interested as a proportion of the entire nominal value of our issued share capital (or any such class of share capital in issue). Where the percentage level of the person's interest does not amount to a whole percentage, this figure is rounded down to the next whole number. We must be notified within five business days of the transaction or alteration of the shareholder's interests that gave rise to the notification requirement. If a person fails to comply with these notification requirements, the person's rights in respect of any of our shares it holds will not be enforceable, either directly or indirectly, by action or legal proceeding. However, such person may apply to the court to have the rights attaching to such shares reinstated.

In addition, Irish law provides that a company may, by notice in writing, require a person whom the company knows or reasonably believes to be or to have been within the three preceding years, interested in its issued voting share capital to: (1) confirm whether this is or is not the case; and (2) if this is the case, to give further information that it requires relating to his or her interest and any other interest in the company's shares of which he or she is aware.

The disclosure must be made within a reasonable period as specified in the relevant notice which may be as short as one or two days. If the recipient of the notice fails to respond within the reasonable time period specified in the notice, we may apply to the Irish High Court for an order directing that the affected shares be subject to certain restrictions, as prescribed by the Irish Companies Act, as follows: (1) any transfer of those shares or, in the case of unissued shares, any transfer of the right to be issued with shares and any issue of shares, shall be void; (2) no voting rights shall be exercisable in respect of those shares; (3) no further shares shall be issued in right of those shares or in pursuance of any offer made to the holder of those shares; and (4) no payment shall be made of any sums due from us on those shares, whether in respect of capital or otherwise.

The court may also order that shares subject to any of these restrictions be sold with the restrictions terminating upon the completion of the sale.

In the event we are in an offer period pursuant to the Irish Takeover Rules, accelerated disclosure provisions apply for persons holding an interest in our securities of one percent or more.

Irish Takeover Rules

Following the completion of the Merger, Trinseo PLC will be subject to the Irish Takeover Panel Act 1997, as amended, and the Irish Takeover Rules promulgated thereunder, or the Irish Takeover Rules, which regulate the conduct of takeovers of, and certain other relevant transactions affecting, Irish public limited companies listed on certain stock exchanges, including the NYSE. The Irish Takeover Rules are administered by the Irish Takeover Panel, which has supervisory jurisdiction over such transactions. Among other matters, the Irish Takeover Rules operate to ensure that no offer is frustrated or unfairly prejudiced and, in the case of multiple bidders, that there is a level playing field. For example, pursuant to the Irish Takeover Rules, the Trinseo PLC Board will not be permitted, without approval from Trinseo PLC's shareholders, to take certain actions that might frustrate an offer for Trinseo PLC once the Trinseo PLC Board has received an approach that may lead to an offer or has reason to believe an offer is, or may be, imminent.

A transaction in which a third party seeks to acquire 30% or more of our voting rights and any other acquisitions of our securities will be governed by the Irish Takeover Panel Act 1997, as amended, and the Irish Takeover Rules and will be regulated by the Irish Takeover Panel. The "General Principles" of the Irish Takeover Rules and certain important aspects of the Irish Takeover Rules are described below.

General Principles

The Irish Takeover Rules are built on the following General Principles which will apply to any transaction regulated by the Irish Takeover Panel: (1) in the event of an offer, all holders of securities of the target company must be afforded equivalent treatment and, if a person acquires control of a company, the other holders of securities must be protected; (2) the holders of securities in the target company must have sufficient time and information to enable them to reach a properly informed decision on the offer; where it advises the holders of

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securities, the board of directors of the target company must give its views on the effects of the implementation of the offer on employment, employment conditions and the locations of the target company's place of business; (3) a target company's board of directors must act in the interests of that company as a whole and must not deny the holders of securities the opportunity to decide on the merits of the offer; (4) false markets must not be created in the securities of the target company, the bidder or any other company concerned by the offer in such a way that the rise or fall of the prices of the securities becomes artificial and the normal functioning of the markets is distorted; (5) a bidder can only announce an offer after ensuring that he or she can fulfill in full the consideration offered, if such is offered, and after taking all reasonable measures to secure the implementation of any other type of consideration; (6) a target company may not be hindered in the conduct of its affairs longer than is reasonable by an offer for its securities; and (7) a "substantial acquisition" of securities, whether such acquisition is to be effected by one transaction or a series of transactions, shall take place only at an acceptable speed and shall be subject to adequate and timely disclosure.

Mandatory Bid

Under certain circumstances, a person who acquires shares, or other voting securities, of a company may be required under the Irish Takeover Rules to make a mandatory cash offer for the remaining outstanding voting securities in that company at a price not less than the highest price paid for the securities by the acquirer, or any parties acting in concert with the acquirer, during the previous 12 months. This mandatory bid requirement is triggered if an acquisition of securities would increase the aggregate holding of an acquirer, including the holdings of any parties acting in concert with the acquirer, to securities representing 30% or more of the voting rights in a company, unless the Irish Takeover Panel otherwise consents. An acquisition of securities by a person holding, together with its concert parties, securities representing between 30% and 50% of the voting rights in a company would also trigger the mandatory bid requirement if, after giving effect to the acquisition, the percentage of the voting rights held by that person, together with its concert parties, would increase by 0.05% within a 12-month period. Any person, excluding any parties acting in concert with the holder, holding securities representing more than 50% of the voting rights of a company is not subject to these mandatory offer requirements in purchasing additional securities.

Voluntary Bid; Requirements to Make a Cash Offer and Minimum Price Requirements

If a person makes a voluntary offer to acquire outstanding Trinseo PLC shares, the offer price must not be less than the highest price paid for Trinseo PLC shares by the bidder or its concert parties during the three-month period prior to the commencement of the offer period. The Irish Takeover Panel has the power to extend the "look back" period to 12 months if the Irish Takeover Panel, taking into account the General Principles, believes it is appropriate to do so.

If the bidder or any of its concert parties has acquired Trinseo PLC shares (1) during the 12-month period prior to the commencement of the offer period that represent more than 10% of the outstanding Trinseo PLC shares or (2) at any time after the commencement of the offer period, the offer must be in cash or accompanied by a full cash alternative and the price per Trinseo PLC share must not be less than the highest price paid by the bidder or its concert parties during, in the case of (1) above, the 12-month period prior to the commencement of the offer period or, in the case of (2) above, the offer period. The Irish Takeover Panel may apply this Rule to a bidder who, together with its concert parties, has acquired less than 10% of the total Trinseo PLC shares in the 12-month period prior to the commencement of the offer period if the Irish Takeover Panel, taking into account the General Principles, considers it just and proper to do so.

An offer period will generally commence from the date of the first announcement of the offer or proposed offer.

Substantial Acquisition Rules

The Irish Takeover Rules also contain rules governing substantial acquisitions of shares and other voting securities which restrict the speed at which a person may increase his or her holding of shares and rights over shares to an aggregate of between 15% and 30% of the voting rights of the company. Except in certain circumstances, an acquisition or series of acquisitions of shares or rights over shares representing 10% or more of the voting rights of the company is prohibited, if such acquisition(s), when aggregated with shares or rights already held, would result in the acquirer holding 15% or more but less than 30% of the voting rights of the company and such acquisitions are made within a period of seven days. These rules also require accelerated disclosure of acquisitions of shares or rights over shares relating to such holdings.

Rights of Dissenting Shareholders

Irish law does not generally provide for appraisal rights. However Irish law provides for dissenters' rights in certain situations, as described below: (1) under a takeover offer, an offeror which has acquired or contracted to acquire not less than 80% of the shares to which the offer relates may require the other shareholders who did not accept the offer to transfer their shares on the terms of the offer. Dissenting shareholders have the right to apply to the High Court of Ireland for relief; (2) a takeover scheme of arrangement which has been approved by the requisite shareholder majority and sanctioned by the High Court of Ireland will be binding on all shareholders. Dissenting shareholders have the right to appear at the High Court hearing and make representations in objection to the scheme; and

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(3) in the case of a domestic or cross-border statutory merger, if the consideration being paid to shareholders is not all in the form of cash, dissenting shareholders may, in certain circumstances, be entitled to require that their shares be acquired for cash.

Anti-Takeover Measures

Frustrating Action

Under the Irish Takeover Rules, the Trinseo PLC Board is not permitted to take any action that might frustrate an offer for our shares once the Trinseo PLC Board has received an approach that may lead to an offer or has reason to believe that such an offer is or may be imminent, subject to certain exceptions. Potentially frustrating actions such as (1) the issue of shares, options, restricted share units or convertible securities; (2) material acquisitions or disposals; (3) entering into contracts other than in the ordinary course of business; or (4) any action, other than seeking alternative offers, which may result in frustration of an offer, are prohibited during the course of an offer or at any earlier time during which the Trinseo PLC Board has reason to believe an offer is or may be imminent. Exceptions to this prohibition are available where: (a) the action is approved by our shareholders at a general meeting; or (b) the Irish Takeover Panel has given its consent, where: (i) it is satisfied the action would not constitute frustrating action; (ii) our shareholders holding more than 50% of the voting rights state in writing that they approve the proposed action and would vote in favor of it at a general meeting; (iii) the action is taken in accordance with a contract entered into prior to the announcement of the offer, or any earlier time at which the Board considered the offer to be imminent; or (iv) the decision to take such action was made before the announcement of the offer and either has been at least partially implemented or is in the ordinary course of business.

Shareholder Rights Plan

Although the Proposed Constitution allows the Trinseo PLC Board to adopt a shareholder rights plan and to grant rights to subscribe for Trinseo PLC ordinary shares or preferred shares thereunder, Trinseo S.A. currently has no intention of adopting a shareholder rights plan or issuing share purchase rights. Irish law does not expressly authorize or prohibit companies from issuing share purchase rights or adopting a shareholder rights plan as an anti-takeover measure. However, there is no directly relevant case law on the validity of such plans under Irish law. In addition, such a plan would be subject to the Irish Takeover Rules and the General Principles underlying the Irish Takeover Rules.

Subject to the Irish Takeover Rules and the terms of the Proposed Constitution and any related shareholder approvals, the Trinseo PLC Board also has power to issue any of our authorized and unissued shares on such terms and conditions as it may determine, and any such action should be taken in Trinseo PLC's best interests. It is possible, however, that the terms and conditions of any issue of preference shares could discourage a takeover or other transaction that holders of some or a majority of the Trinseo PLC shares believe to be in their best interests or in which holders might receive a premium for their shares over the then-market price of the shares.

Insider Dealing

The Irish Takeover Rules also provide that no person, other than the bidder, who is privy to confidential price-sensitive information concerning an offer made in respect of the acquisition of a company (or a class of securities) or a contemplated offer shall deal in relevant securities of the target during the period from the time at which such person first has reason to suppose that such an offer, or an approach with a view to such an offer being made, is contemplated to the time of (i) the announcement of such offer or approach; or (ii) the termination of discussions relating to such offer, whichever is earlier.

Corporate Governance

Under Irish law and the Proposed Constitution, the authority for the overall management of Trinseo PLC is vested in the Trinseo PLC Board. The Trinseo PLC Board may delegate any of its powers on such terms as it thinks fit in accordance with the Proposed Constitution and Irish law, although, the Trinseo PLC Board will remain responsible, as a matter of Irish law, for the proper management of the affairs of Trinseo PLC. The directors must ensure that any delegation is and remains appropriate and that an adequate system of control and supervision is in place.

The Trinseo PLC Board will have a standing audit committee, compensation committee, and nominating and governance committee. It is also the intention of Trinseo PLC to assume Trinseo S.A.'s existing code of business conduct and insider trading policy and to adopt governance guidelines in accordance with Irish law and the NYSE.

Directors

Number of Directors

The Proposed Constitution provides that the number of directors will be as the Trinseo PLC board may determine from time to time, at its discretion, but which shall not be less than three. Immediately following the completion of the Merger there will be the same number of directors on the Trinseo PLC Board that sit on the board of Trinseo S.A.

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Appointment of Directors

Directors are elected by ordinary resolution at general meetings, provided that, if there is a contested election (as provided for in the Proposed Constitution), each of the nominees shall be voted upon as a separate resolution and the nominees who shall be elected as directors shall be only those nominees (in number equal to the number of available positions) who receive the highest number of votes of all nominees in favor of their election or re-election.

Under the Proposed Constitution, shareholders have further notification requirements in addition to what is required under Irish law in order to bring a resolution before a meeting of shareholders. For further detail, see the section captioned "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution—Proposing Resolutions at a General Meeting", beginning on page 49.

Election of Directors

Under the Proposed Constitution, starting with the annual general meeting to be held in 2022, any Director whose term expires at an annual general meeting shall stand for re-election at the annual general meeting. Notwithstanding that a Director might not be re-elected at a general meeting, such Director shall nevertheless hold office until the conclusion of that meeting.

Removal of Directors and Vacancies

Under Irish law and the Proposed Constitution, Trinseo PLC's shareholders have the power to remove a director without cause by simple majority resolution. At least 28 clear days' notice of the resolution is given to Trinseo PLC and the shareholder(s) comply with the relevant procedural requirements.

The power of removal is without prejudice to any claim for damages for breach of contract (e.g., employment contract) which the director may have against Trinseo PLC in respect of his or her removal.

Under Irish law, one or more shareholders representing at least 10% of the paid-up share capital of Trinseo PLC carrying voting rights have the right to requisition the holding of an extraordinary general meeting at which such a resolution to remove a director (and appoint a replacement) may be proposed.

The Proposed Constitution provides that vacancies in the board of directors may be filled by the Trinseo PLC Board.

Duration; Dissolution; Rights upon Liquidation

The duration of Trinseo PLC will be unlimited. Trinseo PLC may be dissolved and wound up at any time by way of a shareholders' voluntary winding up or a creditors' winding up. In the case of a shareholders' voluntary winding up, a special resolution of shareholders is required. Trinseo PLC may also be dissolved by way of court order on the application of a creditor, or by the Companies Registration Office as an enforcement measure if it has failed to file certain returns. Trinseo PLC may also be dissolved by the Director of Corporate Enforcement in Ireland where our affairs have been investigated by an inspector and it appears from the report or any information obtained by the Director of Corporate Enforcement that Trinseo PLC should be wound up.

Under the Proposed Constitution, if Trinseo PLC is wound up and the assets available for distribution among the shareholders of Trinseo PLC are insufficient to repay the whole of the paid-up or credited as paid-up share capital, those assets are required to be distributed so that, as nearly as may be, the losses are borne by the shareholders of Trinseo PLC in proportion to the capital paid-up or credited as paid-up at the commencement of the winding up on the shares in Trinseo PLC held by them respectively. If in a winding-up the assets available for distribution among the Trinseo PLC shareholders are more than sufficient to repay the whole of the share capital paid-up or credited as paid- up at the commencement of the winding-up, the excess is required to be distributed among the shareholders in proportion to the capital at the commencement of the winding-up paid- up or credited as paid-up on the said Trinseo PLC shares held by them respectively. The position described above is subject to any special terms and conditions applying to any class of shares.

No Liability for Further Calls or Assessments

The shares to be issued in connection with the Merger will be duly and validly issued and fully paid and non-assessable.

Transfer and Registration of Shares

Trinseo PLC will maintain a share register or otherwise cause a share register to be maintained. The registration in that register will be used to determine which Trinseo PLC shareholders are entitled to vote at meetings of Trinseo PLC shareholders. A Trinseo PLC shareholder who holds shares beneficially will not be the holder of record of such shares. Instead, the depository or other nominee will be the holder of record of those shares.

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DESCRIPTION OF TRINSEO PLC SHARES

Accordingly, a transfer of shares from a person who holds such shares beneficially to a person who also holds such shares beneficially through a depository or other nominee will not be registered in Trinseo PLC's official share register, as the depository or other nominee will remain the record holder of any such shares.

Under the Proposed Constitution, subject to the Irish Companies Act, certificated shares may be transferred upon surrender for cancellation of the share certificate(s) for the shares in question along with an instrument of transfer, duly executed, with such proof of authenticity of the signature as Trinseo PLC or its agents may reasonably require.

A written instrument of transfer is required under Irish law in order to register on Trinseo PLC's official share register any transfer of shares (i) from a person who holds such shares directly to any other person; (ii) from a person who holds such shares beneficially to a person who will hold such shares directly; or (iii) from a person who holds such shares beneficially to another person who will hold such shares beneficially where the transfer involves a change in the depository or other nominee that is the record owner of the transferred shares. An instrument of transfer is also required for a shareholder who directly holds shares to transfer those shares into his or her own broker account (or vice versa). Such instruments of transfer may give rise to Irish stamp duty, which must be paid prior to registration of the transfer on Trinseo PLC's official Irish share register. However, a shareholder who directly holds shares may transfer those shares into his or her own broker account (or vice versa) and this should not give rise to Irish stamp duty provided there is no change in the ultimate beneficial ownership of the shares as a result of the transfer and the transfer is not made in contemplation of a sale of the shares.

Any transfer of shares in Trinseo PLC that is subject to Irish stamp duty will not be registered in the name of the transferee unless an instrument of transfer is duly stamped and provided to the Trinseo PLC transfer agent. Trinseo PLC, in its absolute discretion and insofar as the Irish Companies Act or any other applicable law permits, may, or may provide that a subsidiary of Trinseo PLC will, pay Irish stamp duty arising on a transfer of shares in Trinseo PLC on behalf of the transferee of such shares. If stamp duty resulting from the transfer of shares in Trinseo PLC which would otherwise be payable by the transferee is paid by Trinseo PLC or any of its subsidiaries on behalf of the transferee, then in those circumstances, Trinseo PLC will, on its behalf or on behalf of its subsidiary (as the case may be), be entitled to (i) seek reimbursement of the stamp duty from the transferee; (ii) set-off the stamp duty against any dividends payable to the transferee of those shares; and (iii) to the extent permitted by law claim a first and permanent lien on the shares on which stamp duty has been paid by Trinseo PLC or its subsidiary for the amount of stamp duty paid. Trinseo PLC's lien shall extend to all dividends paid on those shares. Parties to a share transfer may assume that any Irish stamp duty arising in respect of a transaction in Trinseo PLC shares has been paid unless one or both of such parties is otherwise notified by Trinseo PLC.

The Proposed Constitution delegates to Trinseo PLC's secretary, any assistant secretary or a relevant authorized delegate the authority to execute an instrument of transfer on behalf of a transferor.

To help ensure that our official share register is regularly updated to reflect trading of shares in Trinseo PLC occurring through electronic systems, Trinseo PLC intends to regularly produce such instruments of transfer as may be required to effect any transfers of registered interests in shares. These may involve transactions for which it pays stamp duty, subject to the reimbursement and set-off rights described above. In the event that Trinseo PLC notifies one or both of the parties to a share transfer that it believes stamp duty is required to be paid in connection with such transfer and that it will not pay such stamp duty, the parties may either themselves arrange for the execution of the required instrument of transfer (and may request a form of instrument of transfer from Trinseo PLC for this purpose) or request that Trinseo PLC execute an instrument of transfer on behalf of the transferring party in a form determined by Trinseo PLC. In either event, if the parties to the share transfer have the instrument of transfer duly stamped (to the extent required) and then provide it to Trinseo PLC's transfer agent, the transferee named therein will be registered as the registered holder of the relevant shares on Trinseo PLC's official share register (subject to the matters described below).

The registration of transfers may be suspended by our directors at such times and for such period, not exceeding in the whole 30 days in each year, as our directors may from time to time determine.

Indemnification of Directors and Officers

Subject to exceptions, Irish law does not permit a company to exempt a director or certain officers from, or indemnify a director against, liability in connection with any negligence, default, breach of duty or breach of trust by a director in relation to the company.

The exceptions allow a company to: (a) purchase and maintain directors and officers insurance against any liability attaching in connection with any negligence, default, breach of duty or breach of trust owed to the company; and (b) indemnify a director or such other officer against any liability incurred in defending proceedings, whether civil or criminal: (i) in which judgment is given in his or her favor or in which he or she is acquitted; or (ii) in respect of which an Irish court grants him or her relief from any such liability on the grounds that he or she acted honestly and reasonably and that, having regard to all the circumstances of the case, he or she ought fairly to be excused for the wrong concerned.

The Proposed Constitution includes a provision which entitles every director to be indemnified by Trinseo PLC (including by funding any expenditure incurred or to be incurred by him or her) against any loss or liability incurred in his or her capacity as a director to the fullest extent permitted by law. The Proposed Constitution provides that where a person is so indemnified, such indemnity may extend to all costs, losses, expenses and liabilities incurred by him or her. Any funds provided in compliance with Irish law to a director to meet any

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DESCRIPTION OF TRINSEO PLC SHARES

expenditure incurred by him or her in connection with defending himself or in an investigation of any negligence, default, breach of duty or breach of trust by him or her or otherwise, must be given on the basis of an undertaking from the director that the funds will be repaid if he or she is convicted, or judgment is given against him or her.

The Proposed Constitution also provides the Trinseo PLC Board with authority to purchase and maintain insurance at the expense of Trinseo PLC for the benefit of any person who is, or was at any time, a director or other officer or employee of the company or any associated company.

In addition to the provisions of the Proposed Constitution, it is common for a public limited company to enter into separate a deed of indemnity with a director or officer which essentially indemnifies the director or officer against claims brought by third parties to the fullest extent permitted under Irish law. Trinseo PLC intends to enter into such deeds of indemnity with each of its directors and officers. In addition, given the director indemnification limitations arising under Irish law, it is expected Trinseo PLC will procure that one or more of its subsidiaries will enter into indemnification agreements with each of the Trinseo PLC directors indemnifying them in respect of any liability incurred by them while acting as a director of Trinseo PLC.

Limitation on Director Liability

Subject to exceptions, as described above, Irish law does not permit a company to exempt any director or certain officers from any liability arising from negligence, default, breach of duty or breach of trust against the company. One of the exceptions is that an Irish company is permitted to purchase and maintain insurance for a director or executive officer of the company against any such liability.

Separately, in proceedings where negligence, default, breach of duty or breach of trust against a director has or may be established (or in anticipation of any such proceedings), an Irish court has the power to grant a director or other officer relief from liability on the grounds that he or she acted honestly and reasonably and that, having regard to all the circumstances of the case, he or she ought fairly to be excused for the wrong concerned.

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PROPOSAL 1

Proposal 1—The Merger

Trinseo S.A. shareholders are being asked to approve the Common Draft Terms and the Merger at the General Meeting. Upon the approval thereof, and assuming the other conditions to the Merger are satisfied or waived, Trinseo S.A. shareholders will receive an ordinary share of Trinseo PLC for every ordinary share of Trinseo S.A. that they then hold, on a one-for-one basis.

A cross-border merger of companies from different states within the EEA is governed by Directive 2005/56/EC on Cross-Border Mergers of Limited Liability Companies as repealed and codified by Chapter II, Title II of Directive 2017/1132/EU (the "Directive"), which provides a set of procedures for the merger of companies from different states within the EEA. Because the Merger comes within the scope of the Directive, it must comply with both the Irish Regulations and the relevant provisions of Luxembourg Law, which implemented the Directive in Ireland and Luxembourg, respectively. Although the Directive is binding with respect to the ends it must achieve, each EEA state has a degree of autonomy regarding the means with which it will implement the Directive domestically. Some differences therefore arise between the measures implementing the Directive across EEA jurisdictions, including between Ireland and Luxembourg.

The Merger is to be structured as a "merger by acquisition" under the Irish Regulations and as a "merger by absorption" by Luxembourg Law, the result of which is that all the assets of Trinseo S.A. will be acquired by Trinseo PLC by operation of law and all of the liabilities of Trinseo S.A. will be assumed by Trinseo PLC by operation of law, and Trinseo S.A. will be dissolved without going into liquidation.

Steps Required to Effect the Merger

General Meeting.    On June 14, 2021 we will hold the General Meeting to ask shareholders of record to approve the Common Draft Terms and entry into the Merger.

Luxembourg.

In connection with the Merger, the following steps will occur:

    The Common Draft Terms will be published in the Luxembourg official gazette (RESA) at least one month before the General Meeting;

    The convening notice to the General Meeting will be published with the RESA and with two Luxembourg newspapers and will be sent out by mail to the registered shareholder, directors and Company auditor;

    As of publication of the convening notice all documents required by Luxembourg law will be made available, on a continuous basis, on the Company's website and at the registered office of Trinseo S.A. for inspection by the Trinseo S.A. shareholders;

After the Merger Proposal and resolution to enter into the Merger has been approved by Trinseo S.A. shareholders at the General

Meeting, the following steps must be taken in Luxembourg in order to effect the Merger:

    The Luxembourg notary before whom the General Meeting is held will issue a pre-merger certificate attesting that all formalities required in Luxembourg in connection with the merger have been duly effected which shall be delivered to Trinseo PLC in accordance with Art. 1021-12(2) of the Luxembourg Law;

    The Luxembourg notary will register and file the deed with the Luxembourg Trade and Company Register which will indicate that Trinseo S.A. is currently involved in a merger process.

    Upon receipt of the Final Order, the Luxembourg Trade and Company Register will deregister Trinseo S.A. which will have ceased to exist as of the Effective Date.

Ireland.

In connection with the Merger, the following steps will occur:

    The Common Draft Terms, as well as all other documents required by the Irish Regulations, will be notified to and filed with the Irish Companies Registration Office and will be made available at the registered office of Trinseo PLC in Ireland;

    Such notice and filing will be published in two Irish national daily newspapers and the CRO Gazette;

    Trinseo PLC shareholders will pass a resolution to approve the Common Draft Terms by special resolution under Irish law;

    Application will be made to the Irish High Court for a pre-merger certificate; and

    Subject to issuance of a pre-merger certificate by the Irish High Court and the issuance of a pre-merger certificate by a Luxembourg civil law notary, an application will be made to the Irish High Court for an order to confirm legal scrutiny of the Merger and to set the Effective Date. The hearing of this application will be advertised in Iris Oifigiúil, the international editions of The Financial Times and/or The Wall Street Journal and/or such other publications as the Irish High Court may prescribe. Trinseo S.A. shareholders may attend the approval hearing and make representations at such meeting.

Effectiveness.    If all of the conditions are satisfied or waived (and we do not abandon the Merger before obtaining the Final Order), the Merger will take effect at a time on the Effective Date. We currently anticipate the Merger will take place in October 2021. Once the Merger takes effect as provided for in the Irish Regulations, it may not be declared null and void and the Final Order, specifying the Effective Date, shall constitute conclusive evidence of the effectiveness of the Merger.

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PROPOSAL 1

In connection with the Merger, the following steps will occur by operation of law on the Effective Date:

1.
Trinseo S.A. will be merged with and into Trinseo PLC, with Trinseo PLC as the surviving entity and Trinseo S.A. will cease to exist upon consummation of the Merger;

2.
all assets and liabilities of Trinseo S.A. as at the Effective Date shall transfer to, and be assumed by Trinseo PLC by universal succession of title and by operation of law;

3.
the activities of the Trinseo S.A. business shall be continued by Trinseo PLC;

4.
each Trinseo S.A. shareholder (other than Trinseo S.A.) will receive an ordinary share of Trinseo PLC for every ordinary share of Trinseo S.A. that they then hold, on a one-for-one basis;

5.
in accordance with Luxembourg Law, all Trinseo S.A. treasury shares held by Trinseo S.A. will be canceled by operation of law;

6.
all legal proceedings pending by or against Trinseo S.A. will be continued with the substitution, for Trinseo S.A., of Trinseo PLC as a party; and

7.
contracts, agreements or instruments to which Trinseo S.A. is a party will by operation of law succeed to Trinseo S.A. and be construed and have effect as if Trinseo PLC had been a party thereto instead of Trinseo S.A., and Trinseo PLC will have the same rights and be subject to the same obligations to which Trinseo S.A. is subject to under such contracts, agreements or instruments.

8.
without prejudice to the foregoing, the consequences of the Merger set out in Regulation 19(1) of the Irish Regulations and Art 1021-17 of the Luxembourg Law shall apply to the Merger.

As a result of the Merger, Trinseo S.A. shareholders will become Trinseo PLC shareholders, and Trinseo S.A. will cease to exist.

After the Merger, you will own an interest in a company that will continue to conduct the same functions as conducted by Trinseo S.A. before the Merger. The number of Trinseo PLC shares you will own will be the same as the number of Trinseo S.A. shares you owned immediately before the Merger.

Your rights as a Trinseo S.A. shareholder are currently governed by Luxembourg law and our Articles. Following the Merger, you will become a Trinseo PLC shareholder and your rights as a Trinseo PLC shareholder will be governed by Irish law and the Proposed Constitution. The legal system governing companies organized under Irish law differs from the legal system governing companies organized under Luxembourg law. As a result, while many of the principal attributes of Trinseo S.A. shares and Trinseo PLC shares will be similar under Luxembourg and Irish law, differences will exist.

We discuss these differences in detail below under "Description of Trinseo PLC Shares" and "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution" in Proposal 3.

Expert Reports

As required by the Directive, Trinseo S.A. and Trinseo PLC have each obtained a report from a local independent expert addressing certain matters as required by the Directive, including the experts' views as to whether the securities exchange ratio in the Merger is fair and reasonable. Each merging company will make its expert's report available to their respective shareholders at least one month before the meeting at which they will vote upon the Merger. For this purpose, as permitted by the Directive, Trinseo S.A. has retained PricewaterhouseCoopers, a Luxembourg co-operative company (Société Cooperative) as its independent expert, and Trinseo PLC has retained PricewaterhouseCoopers, a general irish partnership, as its independent expert. A copy of the experts' reports are available on Trinseo S.A.'s website at trinseo.com.

Reasons for the Merger

Our Board believes that giving effect to the Merger will be in the best interests of the Trinseo group and our shareholders. In arriving at this determination, our Board consulted with Trinseo S.A.'s management along with its legal and tax advisors and considered various factors in its deliberations. Our Board concluded that the Merger is likely to result in benefits to the Trinseo group and its shareholders, including, among other benefits, (i) simplifying regulatory requirements, (ii) increasing flexibility on capital deployment such as increased authority to issue new shares or repurchase shares, (iii) providing dividend withholding tax benefits to shareholders and (iv) providing the Trinseo group with operational efficiencies and reduction of its operating and administrative costs. The Merger will also complement the Company's proposed plan to create a global business services center in Ireland. If Trinseo S.A. shareholders approve this proposal, the Merger will effectively change Trinseo S.A.'s legal domicile from Luxembourg to Ireland and will result in other changes of a legal nature, the most significant of which are described under the caption "Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution" in Proposal 3.

We cannot assure you that the anticipated benefits of the Merger will be realized. In addition to the potential benefits described above, the Merger will expose us and you to some risks. These risks include the following:

    your rights as a Trinseo S.A. shareholder will change as a result of the Merger due to differences between Irish law and Luxembourg law and certain differences between the organizational documents of Trinseo PLC and Trinseo S.A.;

    we may choose to abandon or delay the Merger, which may create uncertainty with respect to the tax residency of Trinseo S.A.;

    the transfer of Trinseo PLC shares after the Merger may be subject to Irish stamp duty, subject to any available exemptions and reliefs (for further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations");

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PROPOSAL 1

    dividends paid after the Merger may be subject to DWT in Ireland, subject to available exemptions for tax residents of the United States, any European Union member state (excluding Ireland) or a country that has signed a tax treaty with Ireland provided that, in each case, they file a valid DWT Form with the Irish Revenue Commissioners (for further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations"); and

    Irish capital acquisitions tax may apply to a gift or inheritance of Trinseo PLC shares after the Merger, subject to any available exemptions and reliefs. (for further detail, see "Material Tax Considerations Relating to the Merger—Material Irish Tax Considerations").

For further detail, see "Risk Factors."

Amendment, Termination or Delay

Subject to U.S. securities law, Irish law and Luxembourg law constraints, the Common Draft Terms may be amended, modified or supplemented at any time before or after its approval by Trinseo S.A. shareholders at the General Meeting. However, after approval of the Common Draft Terms by Trinseo S.A. shareholders, no amendment, modification or supplement to the Merger may be made or effected that legally requires further approval by Trinseo S.A. shareholders without obtaining such approval.

Our Board may terminate, abandon or delay the Merger, at any time before the issuance of the Final Order, without obtaining the approval of Trinseo S.A. shareholders, even though the Merger may have been approved by such Trinseo S.A. shareholders and all other conditions to the Merger may have been satisfied or waived.

Conditions to the Consummation of the Merger

The Merger will not be completed unless, among other things, the following conditions are satisfied or, if allowed by law, waived:

    the Merger and the Common Draft Terms are approved by Trinseo S.A. shareholders and Trinseo PLC shareholders;

    the issuance by a Luxembourg notary selected by Trinseo S.A. of the pre-merger certificate and delivery thereto to Trinseo PLC in accordance with Art. 1021-12(2) of the Luxembourg Law;

    the Proposed Constitution is approved by the Trinseo PLC shareholders;

    Trinseo PLC has undertaken certain share capital changes as contemplated by the Common Draft Terms;

    Trinseo S.A. has submitted the Proxy Statement to the Irish High Court;

    Trinseo PLC has advised the Irish High Court that, based on the Final Order, Trinseo PLC will rely upon the exemption from U.S. securities law registration available under Section 3(a)(10) of the Securities Act and it will not register Trinseo PLC shares under the Securities Act;
    advertisements having been placed in the RESA in accordance with Luxembourg law and in such other publications as the Irish High Court orders to ensure that Trinseo S.A. has given Trinseo S.A. shareholders and its creditors prior notice of the hearing of the Irish High Court at which such court will consider the Merger for purposes of approval thereof; and

    the Irish High Court has issued the Final Order.

U.S. Federal Securities Law Consequences

The issuance of Trinseo PLC shares to Trinseo S.A. shareholders in connection with the Merger will not be registered under the Securities Act. Section 3(a)(10) of the Securities Act exempts securities issued in exchange for one or more outstanding securities from the general requirement of registration where the terms and conditions of the issuance and exchange of such securities have been approved by any court of competent jurisdiction, after a hearing upon the fairness of the terms and conditions of the issuance and exchange at which all persons to whom such securities will be issued have a right to appear and to whom adequate notice of the hearing has been given. In determining whether it is appropriate to grant the Final Order confirming scrutiny of the legality of the Merger and setting the Effective Date, the Irish High Court will consider the fairness of the terms and conditions of the Merger to Trinseo S.A. shareholders, such that Trinseo PLC shares issued pursuant to the Merger will constitute an exempt issuance within the meaning of Section 3(a)(10) of the Securities Act.

Upon consummation of the Merger, Trinseo PLC shares will be deemed to be registered under Section 12(g) of the Exchange Act, by virtue of Rule 12g-3 under the Exchange Act, without the filing of any Exchange Act registration statement.

Effective Date and Time of the Merger

The Merger will take effect on the date and time prescribed in the Final Order confirming the scrutiny of the legality of the Merger and determining the fairness of the terms and conditions of the Merger to Trinseo S.A. shareholders and setting the Effective Date. The Final Order specifying the date of effectiveness of the Merger is conclusive evidence of the effectiveness of the Merger.

We intend to propose to the Irish High Court that the Merger take effect in October 2021. The determination of the Effective Date is entirely within the Irish High Court's discretion; however, we are not aware of any reason why it would not grant the requested date.

In the event the conditions to the Merger are not satisfied, the Merger may be abandoned or delayed, even after approval by Trinseo S.A. shareholders. In addition, until the issuance of the Final Order of the Irish High Court, the Merger may be abandoned or delayed by the Trinseo S.A. Board without obtaining the approval of Trinseo S.A. shareholders, even though the Merger may have been approved by such Trinseo S.A. shareholders and all other conditions to the Merger may have been satisfied or waived. For further detail, see "—Amendment, Termination or Delay."

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Management of Trinseo PLC

When the Merger is completed, the executives and directors of Trinseo S.A. immediately prior to completion of the Merger are expected to be the executives and directors of Trinseo PLC.

Interests of Certain Persons in the Merger

No person who has been a director or executive officer of Trinseo S.A., at any time since the beginning of the last fiscal year, or any associate of any such person, has any substantial interest in the Merger, except for any interest arising from his or her ownership of securities of Trinseo S.A., as the case may be. No such person is receiving any extra or special benefit not shared on a pro rata basis by all other Trinseo S.A. shareholders.

Regulatory Matters

Other than as disclosed in this Proxy Statement and the compliance with U.S. Federal and state securities laws and Luxembourg and Irish corporate law, we are not aware of any further governmental approvals or actions that are required to complete the Merger. We do not believe that any significant regulatory approvals will be required to effect the Merger.

No Action Required to Cancel Trinseo S.A. shares and Receive Trinseo PLC shares

Assuming the Merger becomes effective, Trinseo S.A. will cease to exist and fully paid-up, non-assessable Trinseo PLC shares will be issued to you without any further action on your part. All Trinseo PLC shares will be issued in uncertificated form. Our transfer agent, if you are a registered holder, or your bank or brokerage firm, if you hold your shares in "street name," will make an electronic entry in your name and your ownership of

Trinseo PLC shares will be reflected in your account, which you will be able to access in the same way as today.

Accounting Treatment of the Merger

Under U.S. GAAP, the Merger represents a transaction between entities under common control. Assets and liabilities transferred between entities under common control are accounted for at historical cost. Accordingly, the assets and liabilities of Trinseo PLC will be reflected at their carrying amounts in the accounts of Trinseo S.A. at the time of the Merger.

Effect of the Merger on SEC Filing Obligations and SEC Registrant Status

Upon completion of the Merger, we will remain subject to SEC as a successor to the reporting attributes of Trinseo S.A., and we will continue to report our consolidated financial results in U.S. dollars and in accordance with U.S. GAAP. As required by Irish law, in connection with annual general meetings of Trinseo PLC commencing with the 2022 annual general meeting, the Trinseo PLC Irish statutory accounts will also be made available to Trinseo PLC shareholders.

Required Vote

Approval of the Merger Proposal requires at least two-thirds of the votes validly cast in person or by proxy at the General Meeting, at which at least half of the outstanding shares are present or represented. Abstentions and broker non-votes will have no effect on the outcome of this proposal.

Recommendation of the Board

Our Board recommends that Trinseo S.A. shareholders vote "FOR" the Merger Proposal.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR"
APPROVAL OF THE MERGER.

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PROPOSAL 2

Proposal 2—Amendment of the Company's Articles of Association

Our Board of Directors unanimously recommends that our shareholders approve an amendment to our Articles to increase the number of directors serving on the Company's Board of Directors. If this proposal is approved by shareholders, article 7.1.1 of the Articles will be amended and restated as follows:

    7.1.1    The Company shall be managed by the Board, which shall consist of a minimum of three (3) directors and a maximum ofthirteen (13)twelve (12)directors, (each a Director and together, the Directors).

The adoption of this proposed amendment to the Articles will allow the appointment of an additional director to the Board, who is nominated for election by shareholders at this meeting, which the Board believes is in the best interest of Company and its shareholders.

The Articles will be amended if the proposal is approved by shareholders representing two-thirds of the votes validly cast in person or by proxy at the General Meeting. Abstentions and broker non-votes will have no effect on the outcome of this proposal.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR"
APPROVAL OF THE AMENDMENT TO THE ARTICLES OF ASSOCIATION.

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PROPOSAL 3

Proposal 3—Advisory Approval of the Irish PLC Constitution

In connection with adoption of the Merger Proposal, Trinseo S.A. is asking its shareholders to approve, on a non-binding advisory basis, the Proposed Constitution by Trinseo PLC, in the form attached hereto as Annex B (the "Irish Constitution Proposal"). If the Merger Proposal is approved, the Proposed Constitution as set forth in Annex B will be in effect on the Effective Date. The Irish Constitution Proposal is conditioned on the approval of the Merger Proposal. Therefore, if the Merger Proposal is not approved, the Irish Constitution Proposal will have no effect, even if approved by Trinseo S.A. shareholders.

We are asking shareholders to vote on the Irish Constitution Proposal on an advisory basis, to allow shareholders the opportunity to vote for the Proposed Constitution separately from the Merger Proposal. We strongly encourage all shareholders that vote "for" the Merger Proposal to also vote "for" the Irish Constitution Proposal, to allow the Company to proceed with the Merger as intended and set forth in the Merger Proposal.

Comparison of Rights of Shareholders and Governance under the Articles to the Proposed Constitution

Your rights as a Trinseo S.A. shareholder are governed by the Luxembourg law and Trinseo S.A.'s Articles. As a result of the Merger, Trinseo S.A. will be dissolved without going into liquidation and Trinseo S.A. shareholders will become Trinseo PLC shareholders. The rights of Trinseo PLC shareholders will be governed by applicable Irish law, including the Irish Companies Act, and by the Proposed Constitution.

Many of the principal attributes of Trinseo S.A shares and Trinseo PLC shares will be similar. However, there are differences between the rights of Trinseo S.A. shareholders under Luxembourg law and the rights of Trinseo PLC shareholders under Irish law following the Merger. In addition, there are likely to be differences between the Articles and the Proposed Constitution as they will be in effect after the completion of the Merger.

These differences are more particularly described below, but the material differences are generally characterized as follows:

    Trinseo S.A. is a Luxembourg public limited liability company, whereas Trinseo PLC will be an Irish public limited company.

    Certain mandatory provisions under Luxembourg law that are not mandatory provisions of Irish law have not been included in the rights attaching to Trinseo PLC shares and the Proposed Constitution, and certain mandatory provisions under Irish law that are not mandatory provisions of Luxembourg law have been included in the rights attaching to Trinseo PLC shares and the Proposed Constitution.

    Certain standard provisions under Irish law customarily applied to the rights attaching to shares and the constitutions of Irish companies have been included in the rights attaching to Trinseo PLC shares and the Proposed Constitution even if there is no Luxembourg law equivalent.

The following is a summary comparison of the rights of Trinseo S.A. shareholders under applicable Luxembourg law and the Articles and the rights such Trinseo S.A. shareholders will have as Trinseo PLC shareholders under the Irish Companies Act and the Proposed Constitution effective immediately following the Merger. The statements in this section are qualified in their entirety by reference to, and are subject to, the detailed provisions of the Articles and the Proposed Constitution as will be in effect after the Merger, substantially in the form attached as Annex B to this Proxy Statement. We encourage you to read those documents carefully. You are also urged to carefully read the relevant provisions of the Luxembourg Law and the Irish Companies Act for a more complete understanding of the differences between being a Trinseo S.A. shareholder and a Trinseo PLC shareholder. A consolidated version of the Irish Companies Act can be accessed online for free at https://www.lawreform.ie/.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Authorized and Issued Share Capital & Directors Authority to Allot Shares   The authorized share capital of the Company is up to USD $500,000,000 represented by 50,000,000,000 shares. The Company's current issued share capital amounts to USD 487,779.34 represented by 48,777,934 ordinary shares. Approximately 10.4 million ordinary shares are held in Treasury by Trinseo S.A. or a Luxembourg subsidiary. The Company has no preferred shares issued and outstanding. An extraordinary resolution of shareholders, taken before a Luxembourg notary, is required to increase the authorized share capital.

Luxembourg Law requires a shareholder vote to authorize the Board to issue any amount of its authorized share capital without preemptive rights (preferential subscription rights), for a period of up to 5 years. In June 2018, shareholders approved authority for the Board to increase its existing share capital up to 20% without pre-emptive rights and up to 100% with pre-emptive rights, until June 2023.

  The authorized share capital of Trinseo PLC is US$50,000,000 and €25,000, comprised of 4,000,000,000 ordinary shares, par value US$0.01 per share, 1,000,000,000 preferred shares, par value US$0.01 per share, and 25,000 deferred ordinary shares, par value €1.00 per share. The deferred ordinary shares will have no voting or dividend rights from the Effective Date but are required under Irish law for capitalization purposes. Any proposed increase in the authorized share capital of an Irish company must be approved by ordinary resolution of shareholders in general meeting.

Under Irish law, the directors of a company may issue new ordinary or preferred shares without shareholder approval once authorized to do so by the constitution or by an ordinary resolution adopted by the shareholders at a general meeting. The Proposed Constitution authorizes the Trinseo PLC Board to issue shares of any class in Trinseo PLC, up to the amount of its authorized but unissued share capital, without shareholder approval for a period of five years from the date of adoption of such constitution. This authority must be renewed by the shareholders by ordinary resolution.

Under Irish law, statutory preemption rights apply automatically where shares are issued for cash. The Proposed Constitution will permit the Trinseo PLC Board to disapply statutory preemptive rights in any issuance of shares, for a period of five years. The disapplication of preemptive rights must be renewed by shareholders at least every five years by special resolution (75% of votes cast) at a general meeting of shareholders.

The Trinseo PLC Board will also be authorized to issue preferred shares with discretion as to the terms attaching to the preferred shares, including as to voting, dividend and conversion rights and priority relative to other classes of shares with respect to dividends and upon a liquidation.

Consolidation and Division   Trinseo S.A. may, by extraordinary resolution, consolidate and divide all or any of its share capital into shares of larger par value than its existing shares, or subdivide its shares into smaller amounts.   Trinseo PLC may, by ordinary resolution, consolidate and divide all or any of its share capital into shares of larger par value than its existing shares, or subdivide its shares into smaller amounts.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Pre-Emption Rights (Generally)   Under Luxembourg Law, shares to be subscribed for in cash must be offered on a preferential basis to the shareholders in proportion of the capital represented by their shares. The pre-emptive subscription rights may be excluded from application to specific share classes which have different rights to participate in distributions or in the assets in the event of liquidation. The articles may also provide that, where the subscribed capital of a company with several classes of shares is increased by issue of new shares of only one class, the pre-emptive subscription rights of the holders of shares of the other class may not be exercised until after the right has been exercised by the holders of the shares of the class in which the new shares are issued. The shareholders may, by extraordinary resolutions, limit or withdraw pre-emptive subscription rights or authorize the board of directors to do so, subject to observing the procedure set out in the Luxembourg Law.   Under Irish law, certain statutory preemption rights apply automatically in favor of shareholders where shares are to be issued for cash unless those rights are disapplied in the constitution of the company or by special resolution of its shareholders. Statutory preemption rights do not apply (i) where shares are issued for non-cash consideration (such as in a stock-for-stock acquisition); (ii) to the issue of non-equity shares (that is, shares that have the right to participate only up to a specified amount in any income or capital distribution); or (iii) where shares are issued pursuant to an employee stock option or similar equity plan.
Board of Directors, Election of Directors and Vacancies on the Board of Directors   Pursuant to the Luxembourg Law, the Board must be composed of at least three directors. They are appointed by the shareholders (by proposal of the board, the shareholders or a spontaneous candidacy) by a simple majority of the votes cast. The term of office pursuant to the Articles may not exceed the period separating the shareholders appointing the director and the succeeding annual general meeting of shareholders, but they may be re-elected.

Pursuant to the Articles, directors are elected by an ordinary resolution at a general meeting and a simple majority of votes validly cast on such resolution, provided that a quorum of 50% of the share capital of the company is present or represented. If the said quorum is not present, a second meeting may be convened with the same agenda at which Luxembourg law does not prescribe a quorum. The Articles provide that in case of a vacancy, the remaining board members may elect a director to provisionally fill the vacancy.

The Articles provide that vacancies due to resignation or otherwise may be filled on a temporary basis pursuant to the affirmative vote of a majority of the remaining directors. Such decision must be ratified by an ordinary resolution of the next general meeting.

  The Irish Companies Act provides for a minimum of two directors on the board of a PLC. The Proposed Constitution provides that the number of directors will be as the Trinseo PLC board may determine from time to time, at its discretion, but which shall not be less than three.

Directors are elected on an individual basis by way of separate ordinary resolutions at a general meeting and a simple majority of votes validly cast on such resolution. Where the number of valid nominees exceeds the number of director seats to be filled (a contested election), each of the nominees shall be voted upon as a separate resolution and the nominees who shall be elected as directors shall be only those nominees (in number equal to the number of available positions) who receive the highest number of votes of all nominees in favor of their election or re-election.

The Proposed Constitution provides that the Trinseo PLC Directors have the power to appoint a person either to fill a vacancy or as an additional director. Under the Proposed Constitution, starting with the annual general meeting to be held in 2022, any Director whose term expires at an annual general meeting shall stand for re-election at the annual general meeting. Notwithstanding that a Director might not be re-elected at a general meeting, such Director shall nevertheless hold office until the conclusion of that meeting.

Removal of Directors   Pursuant to the Luxembourg Law, directors may be removed at any time with or without cause by ordinary resolution at a general meeting of shareholders adopted by a simple majority of the votes cast on such resolution.   Under Irish law and the Proposed Constitution, shareholders may remove a director without cause by ordinary resolution, provided that at least 28 clear days' notice of the resolution is given to Trinseo PLC and the shareholder(s) comply with the relevant procedural requirements.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Remuneration of Directors   Director's remuneration is set by the shareholders (save potentially for any remuneration paid out as salary to an employee director, which shall be approved by the board of directors). The amount of the fees granted in respect of the financial year to a director, and the amount of any commitments arising or entered into under the same conditions in respect of retirement pensions for former directors should be disclosed in the notes to the stand-alone accounts.   Under Irish law, Trinseo PLC is not required to prepare and submit to shareholders a directors' remuneration report or policy for a vote. Irish law requires, in the case of officers who are also considered directors under Irish law, that employment agreements with a guaranteed term of more than five years be subject to a prior approval of shareholders at a general meeting.
Quorum for Board Meetings   The Trinseo S.A. Board may only validly deliberate and act if a majority of the directors and the chairman of the Board are present or represented. If this quorum is not reached, a second Board meeting must be convened with the same agenda and such reconvened Board meeting may validly deliberate and act if a majority of its members are present or represented.   No business shall be transacted at any meeting of the Trinseo PLC Board unless a quorum is present. The quorum necessary for the transaction of the business of the Board may be fixed by the Board and unless so fixed shall be a majority of the Directors in office.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Duties of Directors   Under Luxembourg Law, the directors manage its affairs and have the power to take any action they consider necessary or useful to realize its corporate purpose, unless that action is reserved to the shareholders (e.g., approval of the annual accounts) by the Luxembourg Law or the articles of association of the company. The board of directors is thus a company's main decision-making body, and is in charge of determining the guidelines for its management and business development.

The directors represent the company, and must exercise their duties with as much care, diligence and skill as would be displayed by a reasonable director in the same circumstances. Although Luxembourg law, unlike common law jurisdictions, contains no such concept as "fiduciary duty" of directors, the directors must also act with loyalty, honesty and in good faith, for the company's exclusive benefit. Hence they must participate in board meetings and manage the company actively.

Luxembourg Law sets forth the main specific duties of a director as follows:

(a)    to prepare each year an inventory indicating the value of the company's assets and debts, with an annex summarizing all the commitments and debts of the company's officers, directors and statutory auditors;

(b)    to prepare the annual accounts (balance sheet, profit and loss account and annex);

(c)    to establish a report on the company's business (the Management Report), if required,

(d)    to submit the annual accounts, the consolidated accounts (if required by law), the Management Report and the report of the person responsible for auditing the company (if any) to the shareholders for approval, within six months after the end of the financial year; and

(e)    to file the approved annual accounts, the Management Report and the report drawn up by the statutory auditor(s) (in public limited liability companies) with the RESA within one month following their approval by the annual general meeting, and no later than seven months after the end of the financial year.

  Under Irish law, a fiduciary relationship exists between the directors and the company. The Irish Companies Act sets out eight principal fiduciary duties for directors, which are derived from common law and equitable principles, as follows:

(a)    to act in good faith in what the director considers to be the interests of the company;

(b)    to act honestly and responsibly in relation to the conduct of the affairs of the company;

(c)    to act in accordance with the company's constitution and to exercise his or her powers only for the lawful purposes;

(d)    not to misuse the company's property, information and/or opportunity;

(e)    not to fetter their independent judgement.

(f)    to avoid conflicts of interest;

(g)    to exercise due care, skill and diligence; and

(h)    to have regard to the interests of the company's employees in general and its shareholders.

Additional statutory duties of directors include ensuring the maintenance of proper books of account, having annual statutory accounts prepared and audited, maintaining certain registers, making certain filings and disclosing personal interests in securities of, and transactions with, Trinseo PLC. Directors of public limited companies, such as Trinseo PLC also have a specific duty to ensure that the company secretary is a person with the requisite knowledge and experience to discharge the role.

Such duties are owed to the company (not to individual shareholders or third parties) and only the company may take an action for breach of duty against a director. On a liquidation, this power may be exercised by the liquidator. In limited situations, shareholders may be able to bring a derivative action on behalf of the company.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Conflict of Interest of Directors   If a director has a direct or indirect financial interest conflicting with that of the company in a transaction which is submitted for approval to the board of directors he or she must advise the board of such interest and cause a record of the statement to be included in the minutes of the meeting. Such director may not participate in deliberations and decision-making in relation to the transaction. Further, a special report must be made in relation to the relevant transaction and presented at the next general meeting, before any other resolution is put to vote. Where, because of conflict of interests, the number of directors required by the articles to decide and vote on the relevant matter is not reached, the board of directors may, unless otherwise provided for by the articles of association, decide to escalate the decision on that matter to the shareholders. The preceding rules do not apply where the decision of the board of the directors relates to ordinary business entered into under normal conditions.   As a matter of Irish law, a director is under a general fiduciary duty to avoid conflicts of interest. An Irish company is required to maintain a register of declared interests, which must be available for shareholder inspection. The Proposed Constitution provides that a director must declare any interest he or she may have in an existing or proposed contract, transaction or arrangement with Trinseo PLC at a meeting of the board of directors or otherwise provide notice to the board of directors, and that no director shall be prevented by his or her office from contracting with the company, provided that he or she has declared the nature of his or her interest in the contract or transaction and the contract or transaction has been approved by a majority of the disinterested directors.
Related Party Transactions   Luxembourg law does not prohibit related party transactions. However, a transaction between the company and one of its directors will be subject to the conflict of interest rules.   Under Irish law, certain transactions between Trinseo PLC and any director of Trinseo PLC are prohibited unless approved by the shareholders, such as loans, credit transactions and substantial property transactions. This prohibition extends to transactions with close personal relations and companies controlled by any such director.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Limited Liability and Indemnification of Directors   The Luxembourg Law provides that directors do not assume any personal obligations for commitments of the company. Directors are liable to the company for the performance of their duties as directors and for any misconduct in the management of the company's affairs. Directors are further jointly and severally liable both to the company and to any third parties for damages resulting from violations of the law or the articles of association of the company. Directors will only be discharged from such liability for violations to which they were not a party, provided no misconduct is attributable to them and they have reported such violations at the first general meeting after they had knowledge thereof. In addition, directors may under specific circumstances also be subject to criminal liability, such as in the case of an abuse of assets.

The Articles provide that the Company may indemnify directors and officers, past and present, to the fullest extent permitted by Luxembourg Law against liability and all expenses reasonably incurred or paid by him or her in connection with any claim, action, suit or proceeding in which he/she is involved by virtue of his being or having been a director or officer and against amounts paid or incurred by him or her in the settlement thereof, subject to certain exceptions.

  Pursuant to the Proposed Constitution, a person who is or was a director, officer or executive of Trinseo PLC shall generally be entitled to be indemnified by Trinseo PLC against all costs, charges, losses, expenses and liabilities incurred by him or her in the execution and discharge of his duties or in relation thereto to the maximum extent permitted by Irish law.

The Irish Companies Act prescribes that any provision which purports to indemnify an officer of the company from liability for negligence or breach of duty is void. However, a director may be indemnified for such a breach of duty or negligence and the company permitted to pay the costs or discharge the liability of a director or the secretary where judgment is given in any civil or criminal action in respect of such costs or liability, or where an Irish court grants relief because the director or secretary acted honestly and reasonably and ought fairly to be excused. Any provision whereby an Irish company seeks to commit in advance to indemnify its directors or secretary over and above the limitations imposed by the Irish Companies Act will be void under Irish law. This restriction does not apply to Trinseo PLC's executives who are not directors or the secretary of Trinseo PLC.

Irish law permits a company to purchase and maintain insurance on behalf of its directors. Given the director indemnification limitations arising under Irish law, it is expected Trinseo PLC will procure that one or more of its subsidiaries will enter into indemnification agreements with each of the Trinseo PLC directors indemnifying them in respect of any liability incurred by them while acting as a director of Trinseo PLC.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Derivative Actions   Luxembourg law does not require shareholder approval before legal action may be initiated on behalf of the company. The board of directors has sole authority to decide whether to initiate legal action to enforce the company's rights (other than, in certain circumstances, in the case of an action against board members).

Under Luxembourg Law, minority shareholders may bring an action on behalf of the company against board members, provided that at the general meeting of shareholders which voted on the discharge of such board members, they held at least ten per cent. (10%) of the voting rights.

Indirect action can in principle be taken in the event of any failure or default (as opposed to a refusal) on the part of the corporate body (typically, the board of directors) responsible to take required action on behalf of the company to exercise or enforce the latter's rights.

Although it is clear that such a course of action is recognized in respect of third party creditors (exercising, in this case, the rights of the company itself on behalf of the company), it does not, in principle, apply to minority shareholders insofar as legal literature is reluctant to regard minority shareholders as creditors of the company (a qualifying condition for action).

  Under Irish law, the power to initiate a lawsuit on behalf of the company is generally a matter for the board of directors, and shareholders' rights to initiate a derivative lawsuit on behalf of the company are limited. A shareholder may generally be entitled to bring a derivative action is if a wrong committed against the company would go unredressed. The principal case law in Ireland indicates that to bring a derivative action, a person must first establish a prima facie case: (a) that the company is entitled to the relief claimed and (b) that the action falls within one of five exceptions derived from case law.

While Irish law only permits a shareholder to bring a derivative action and initiate a lawsuit on behalf of the company in limited circumstances, it does permit a shareholder whose name is on the register of shareholders of a company to apply for a court order where the company's affairs are being conducted or the powers of the company's directors are being exercised in a manner oppressive to him or her or any of the shareholders; or in disregard of his or her or their interests as shareholders. This is a statutory remedy and an Irish court has wide discretion to make such order as it sees fit (the usual remedy is the purchase or transfer of the shares of any shareholder).

Lawsuits brought by a shareholder on behalf of the company may be brought exclusively in the courts of Ireland when they are related to or in connection with a derivative claim, an alleged breach of fiduciary or other duty by a director, officer or employee of Trinseo PLC or any other claim against Trinseo PLC or its directors, officers and employees under Irish law or pursuant to the constitution.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Amendment of Governing Documents   Under the Luxembourg Law, amendments to Articles require an extraordinary general meeting of shareholders held in front of a public notary at which at least one half of the share capital is represented. Resolutions will be adopted if approved by at least two-thirds of the votes validly cast (unless otherwise mandatorily required by Luxembourg law). An increase of the commitments of the company's shareholders require the unanimous consent of the shareholders (and bondholders, if any).

The Articles provide that for any extraordinary resolutions to be considered at a general meeting the quorum shall be at least one half (50%) of the issued share capital of the Company. Any extraordinary resolution shall be adopted at a quorate general meeting (save as otherwise provided by mandatory law) by a two-thirds (2/3) majority of the votes validly cast on such resolution.

In very limited circumstances the Board may be authorized by the shareholders to amend the Articles, albeit always within the limits set forth by the shareholders. This is the case in the context of the Company's authorized share capital within which the Board is authorized to issue further shares or in the context of a share capital reduction and cancellation of shares. The Board is then authorized to appear in front of a notary public to record the capital increase or decrease and to amend the share capital set forth in the Articles.

  Irish companies may alter their memorandum and articles of association only by the passing of a special resolution of shareholders. There are no special quorum requirements for such a meeting, outside of the usual quorum requirements that apply for general meetings.
Shareholder Meetings   Pursuant to the Luxembourg Law, at least one general meeting of shareholders must be held each year on the day and at the time indicated in the articles of association of the company. The purpose of such annual general meeting is to approve the annual accounts, allocate the results, proceed to statutory appointments and grant discharge to the directors. The annual general meeting must be held within six months of the end of each financial year.   An Irish company is required to hold an annual general meeting ("AGM") each year at intervals of no more than 15 months from the previous AGM and no later than 9 months after its accounting year end. The business of Trinseo PLC's annual general meeting is required to include: (a) the consideration of Trinseo PLC's statutory financial statements and reports of the directors and auditors thereon; (b) the review by shareholders of Trinseo PLC's affairs; (c) the election and re-election of Directors in in accordance with the Proposed Constitution; (d) the appointment or re-appointment of the statutory auditors; (e) the authorizing of the directors to approve the remuneration of the auditors; and (f) the declaration of dividends (other statutory than interim dividends). Shareholder meetings can be held outside Ireland so long as Trinseo PLC makes all necessary arrangements to ensure that shareholders can by technological means participate in any such meeting without leaving Ireland.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Calling of Special Meetings of Shareholders   Pursuant to Luxembourg Law, the board of directors is obliged to convene a general meeting so that it is held within a period of one month of the receipt of a written request of shareholders representing 10% of the issued capital. Such request must be in writing and indicate the agenda of the meeting.   Under Irish law, one or more shareholders representing at least 10% of the paid-up share capital of Trinseo PLC carrying voting rights have the right to requisition the holding of an extraordinary general meeting. The requisition notice must set out the objects of the meeting and be deposited at the registered office of the company. Upon receipt of any such valid requisition notice, the board of the PLC has 21 days to convene a meeting of shareholders to vote on or consider the matters set out in the requisition notice. This meeting must be held within two months of the deposit of the requisition notice (the "requisition date"). If the PLC board fails to convene the meeting within such 21 day period, the requisitionists, or any of them representing more than one half of the total voting rights of all of them, may themselves convene a meeting, which meeting must be held within three months of the requisition date.
Proposing Resolutions at a General Meeting   Shareholders holding at least 10% of the share capital of the company may request that one or more additional items be put on the agenda of any general meeting. This request shall be sent to the registered office by registered mail at least five days prior to the holding of the meeting.

Under the Articles, shareholders have further notification requirements in addition to what is required under Luxembourg Law in order to bring a resolution before a meeting of shareholders.

  Shareholders do not have a general right under Irish law to put items on the agenda of a general meeting of Trinseo PLC (except as described above under "Calling of Special Meetings of Shareholders").

The Proposed Constitution sets out specific requirements that must be complied with where a shareholder proposes to bring any business before a general meeting of Trinseo PLC. Any such proposals will be required to be put to a general meeting only where they fully comply with all the notification and other requirements of the Proposed Constitution and Irish law.

For notices relating to the nomination of directors, shareholders must provide, among other things, all information required to be disclosed in a proxy statement soliciting proxies for the election of such nominee as a director in an election contest or that is otherwise required pursuant to Regulation 14A under the Exchange Act and the rules and regulations promulgated thereunder.

For notices relating to any other business, further information including a comprehensive description of the business desired to be brought before the meeting, the complete text of any proposed resolution and a declaration of any material interest in such business by shareholders and any associated persons are required.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Notice for General Meetings   The Articles require convening notices to be published at least 30 days before the date of the general shareholders meeting.   The Proposed Constitution requires that notice of an annual general meeting of shareholders must be delivered to the shareholders at least 21 clear days before the meeting. Shareholders must be notified of all general meetings (other than annual general meetings) at least 14 clear days prior to the meeting (provided that, in the case of an extraordinary general meeting for the passing of a special resolution, at least 21 clear days' notice is required). Notice periods for general meetings can be shortened if all shareholders entitled to attend and vote at the meeting agree to hold the meeting on short notice. The Company will continue to be bound by U.S. securities regulations governing notice & proxy statement delivery.
Quorum for General Meetings   Ordinary Resolutions: a quorum of at least 50% of the share capital present or represented is required. If said quorum is not met, a second meeting may be convened with the same agenda at which no quorum shall apply.

Extraordinary Resolutions: Pursuant to the Articles, for any extraordinary resolutions to be considered at a general meeting the quorum shall generally be at least one half (50%) of the issued share capital. If the said quorum is not present, a second meeting may be convened at which Luxembourg Law does not prescribe a quorum.

  Under the Proposed Constitution, no business other than the appointment of a chairman shall be transacted at any general meeting unless a quorum of members is present at the time when the meeting proceeds to business. Under the Proposed Constitution, holders of at least a simple majority of the shares issued and entitled to vote at a general meeting, constitute a quorum.
Serious Loss of Capital   When, after a loss, the net assets of the company are reduced to an amount lower than half of the share capital, the board of directors must convene a general meeting so that it is held no more than two months from the time when they ascertained the loss or should have ascertained it, and that meeting must resolve on the possible dissolution of the company and possibly any other measures included in the agenda.

The same rules must be observed when, after a loss, the net assets are reduced to an amount lower than one quarter of the share capital, except that in this case the company must be dissolved if this is approved by one quarter of the votes cast at the meeting.

  If the directors of Trinseo PLC become aware that the assets of Trinseo PLC are half or less of the amount of Trinseo PLC's called-up share capital, the directors must convene an extraordinary general meeting of Trinseo PLC not later than 28 days after the earliest day on which that fact is known to a director (and the general meeting must be convened for a date not later than 56 days from that day). The meeting must be convened for the purpose of considering whether any, and if so what, measures should be taken to address the situation.

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Voting Rights   The Articles provide that any ordinary resolutions shall be adopted by a simple majority of votes validly cast on such resolution with a quorum of at least 50% of the share capital present or represented.

The Articles provide that unless otherwise mandatorily required by law for any extraordinary resolutions to be considered at a general meeting. Any extraordinary resolution shall be adopted at a quorate general meeting (save as otherwise provided by mandatory law) at a two-thirds (2/3) majority of the votes validly cast on such resolution. Extraordinary Resolutions: extraordinary resolutions are required for any of the following matters: (a) an increase or decrease of the authorized or issued capital, (b) a limitation or exclusion of pre-emptive rights, (c) approval of a statutory merger or de-merger, (d) dissolution and (e) an amendment of the articles of association.

  Irish law requires approval of certain matters by "special resolution" of the shareholders at a general meeting. A special resolution requires the approval of not less than 75% of the votes of shareholders cast at a general meeting at which a quorum is present. A special resolution is needed (among other matters) to alter a company's constitution, exclude statutory pre-emptive rights on allotment of securities for cash (up to five years), reduce a company's share capital and re-register a public company as a private company (or vice versa). Ordinary resolutions, by contrast, require a simple majority of the votes of shareholders cast at a general meeting at which a quorum is present. An ordinary resolution is needed (among other matters) to remove a director; provide, vary or renew the directors' authority to allot shares and to appoint directors (where appointment is by shareholders). Abstentions are not considered "votes."

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PROPOSAL 3

Provision

Trinseo S.A.

Trinseo PLC
Shareholder Approval of Business Combinations   Any type of business combination that would require an amendment to the articles of association, such as a merger, de-merger, consolidation, dissolution or voluntary liquidation, requires an extraordinary resolution of a general meeting of shareholders.

Transactions such as a sale, lease or exchange of substantial company assets require only the approval of the Board. Neither Luxembourg Law nor the Articles contain any provision specifically requiring the board of directors to obtain shareholder approval of the sale, lease or exchange of substantial assets of the Company.

  Irish law recognizes the concept of a statutory merger for:

(1)    a domestic merger where an Irish private limited company merges with another Irish company (not a public limited company);

(2)    a domestic merger where an Irish public limited company merges with another Irish company; and

(3)    a cross-border merger, where an Irish company merges with another company based in the European Economic Area.

Under Irish law, where Trinseo PLC proposes to acquire another company, approval of Trinseo PLC's shareholders is not required, unless effected as a direct domestic merger or direct cross-border merger as referred to above. Under Irish law, where another company proposes to acquire Trinseo PLC, the requirement for the approval of Trinseo PLC's shareholders depends on the method of acquisition:

Schemes of Arrangement
Under Irish law, schemes of arrangement are arrangements or compromises between a company and any class of shareholders or creditors, and are used in certain types of reconstructions, amalgamations, capital reorganizations or takeovers (similar to a merger in the United States). Such arrangements involving shareholders only require the approval of: (i) a majority in number of shareholders representing 75% by value of shareholders (or each class thereof) present and voting either in person or by proxy at a special meeting convened by order of the court; and (ii) the Irish High Court.

Takeover Offers
The Irish Companies Act also provides that where (i) a takeover offer is made for shares, and (ii) following the offer, the offeror has acquired or contracted to acquire not less than 80% of the shares to which the offer relates, the offeror may require the other shareholders who did not accept the offer to transfer their shares on the terms of the offer.

Statutory Mergers
It is also possible for Trinseo PLC to be acquired by way of a domestic or cross-border statutory merger, as described above. Such mergers must be approved by a special resolution of shareholders.

Irish law does not generally require shareholder approval for a sale, lease or exchange of all or substantially all of a company's property and assets.

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Provision

Trinseo S.A.

Trinseo PLC
Shareholder Consent to Action Without a Meeting   A shareholder meeting must always be called if the matter to be considered requires a shareholder resolution under Luxembourg Law or the Articles.

Pursuant to Luxembourg law, shareholders of a public limited liability company may not take actions by written consent. All shareholder actions must be approved at an actual meeting of shareholders held before a notary public or under private seal, depending on the nature of the matter. Shareholders may vote by proxy.

  Under the Proposed Constitution, shareholders may approve a resolution without a meeting if all shareholders sign the written resolution.
Distributions and Dividends   Pursuant to Luxembourg law, dividend distributions may be declared by (i) the shareholder at a general meeting or (ii) the Board in the case of interim dividends. The amount of distributions declared by the annual general meeting of shareholders shall include (i) the amount previously declared by the Board (i.e., the interim distributions for the year of which accounts are being approved), and if proposed (ii) the (new) distributions declared on the annual accounts. Interim dividend distributions may only be made if (i) the interim accounts, no older than two months, indicate sufficient funds available for distribution; (ii) the amount to be distributed may not exceed total net profits since the end of the preceding fiscal year; and (iii) a report of the statutory auditor addressed to the Board confirms that the above conditions have been met.   Under Irish law, dividends and distributions may only be made from profits available for distribution. In addition, under Irish law Trinseo PLC is not permitted to make a distribution or dividend unless its net assets are equal to, or in excess of, the aggregate of its called up share capital plus undistributable reserves and the distribution does not reduce the its net assets below such aggregate. Undistributable reserves includes a company's undenominated capital and the amount by which the company's accumulated unrealized profits, so far as not previously utilized by any capitalization, exceed its accumulated unrealized losses, so far as not previously written off in a reduction or reorganization of capital.

Distributable profits generally means accumulated realized profits less accumulated realized losses and includes reserves created by way of capital reduction. The Proposed Constitution authorizes the directors to declare and pay interim dividends without shareholder approval to the extent they appear justified by the profits of Trinseo PLC available for distribution. The Trinseo PLC Board may also recommend a dividend to be approved and declared by the shareholders by ordinary resolution at a general meeting. No dividend issued may exceed the amount recommended by the directors. Dividends may be declared and paid in cash by cheque or warrant or sent by any electronic or other means of payment.

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Provision

Trinseo S.A.

Trinseo PLC
Repurchases and Redemptions   The Company may repurchase its own shares subject to certain conditions set out in the Luxembourg Law and in particular, subject to the following conditions: (a) an authorization to acquire shares is approved by shareholders, which shall determine the terms and conditions of the proposed acquisition, the maximum number of shares to be acquired, the duration of the period for which the authorization is given and which may not exceed 5 years and, in the case of acquisition for value, the maximum and minimum consideration; (b) the acquisition must pass the "balance sheet test" provided by the Luxembourg Law; (c) only fully paid-up shares may be included in such transaction; and (d)equal treatment of shareholders who are in the same position is to be respected. Listed companies may repurchase their own shares on the stock exchange without an acquisition offer having to be made to the shareholders.

The Company must dispose of its acquired shares within 3 years of their acquisition, unless their nominal value does not exceed 10 percent of the subscribed capital. The voting rights attached to acquired shares are suspended and, if the shares are included in the assets shown in the balance sheet, a non-distributable reserve of the same amount must be created among the liabilities of the company. The Board may decide to suspend the economic rights attached to such shares. The shares are not taken into account for determining the quorum and majority conditions for general meetings.

  The Proposed Constitution provides that Trinseo PLC may purchase its own shares and redeem outstanding redeemable shares. Under Irish law, shares can only be purchased or redeemed out of: (i) distributable profits; or (ii) the proceeds of a new issue of shares made for the purpose of the purchase or redemption. A company may purchase its own shares either (i) "on-market" on a recognized stock exchange, which includes NYSE; or (ii) "off-market" (i.e.,  otherwise than on a recognized stock exchange). To make "on-market" purchases of shares, shareholders must provide general authorization to the company to do so by way of an ordinary resolution. Such authority can be given for a maximum period of five years before it requires to be renewed and must specify: (i) the maximum number of shares that may be purchased; and (ii) the maximum and minimum prices that may be paid for the shares by specifying particular sums or providing a formula. For an "off-market" purchase, the proposed purchase contract must be authorized by special resolution of the shareholders before the contract is entered into.

Under the Proposed Constitution, the company can redeem (as opposed to purchase) its redeemable shares, without the requirement for additional shareholder authority. The Proposed Constitution provides that, unless the Trinseo PLC Board determines otherwise, any Trinseo PLC share that Trinseo PLC has agreed to acquire shall be automatically converted into a redeemable share. Repurchased and redeemed shares may be cancelled or held as treasury shares, provided that the par value of treasury shares held by Trinseo PLC at any time must not exceed 10% of the company capital of Trinseo PLC.

Reduction of Share Capital   The shareholders may reduce the share capital of the company by extraordinary resolution. The minimum capital requirements (e.g., share capital at least equal to EUR 30,000) must be respected at any time.   Trinseo PLC may, by special resolution, reduce its share capital by way of a court approved procedure that also requires approval by special resolution of Trinseo PLC's shareholders at a general meeting.

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Provision

Trinseo S.A.

Trinseo PLC
Regulation of Takeovers / Anti-takeover measures   The scope of application of the Luxembourg law provisions regarding takeovers and anti-takeover rules is limited to Luxembourg companies listed on a European regulated market. As a result, these rules do not apply to Trinseo S.A.   Takeover offers and certain other transactions in respect of Irish registered public companies listed on certain stock exchanges, including NYSE, are regulated by the Irish Takeover Panel Act 1997, Irish Takeover Rules 2014 (the "Irish Takeover Rules"). The Irish Takeover Rules are administered by the Irish Takeover Panel, which oversees the conduct of such transactions. Trinseo PLC, as an Irish registered public limited company, listed on NYSE is subject to the Irish Takeover Rules and the supervisory jurisdiction of the Irish Takeover Panel. Among other matters, the Irish Takeover Rules operate to ensure that no offer is frustrated or unfairly prejudiced and, in the case of multiple bidders, that there is a level playing field. For example, pursuant to the Irish Takeover Rules, the Trinseo PLC Board will not be permitted to take actions, without shareholder approval, which might result in the frustration of an offer, or potential offer, for the shares of Trinseo PLC once the Trinseo PLC Board has received an approach which might lead to an offer or has reason to believe that an offer is, or may be, imminent.

The Proposed Constitution provides the Trinseo PLC Board with the power to establish a rights plan and to grant rights to subscribe for ordinary or preferred shares in Trinseo PLC pursuant to a rights plan. Pursuant to the Irish Takeover Rules, the Trinseo PLC Board will not be permitted, without shareholder approval, to take certain actions that might frustrate an offer for Trinseo PLC once the Trinseo PLC Board has received an approach that may lead to an offer or has reason to believe an offer is, or may be, imminent. The adoption and operation of any rights plan will be subject to the Irish Takeover Rules, which may impact on when a plan can be adopted, or rights issued thereunder.

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Provision

Trinseo S.A.

Trinseo PLC
Rights on Liquidation   Under the Articles, the liquidators appointed by the shareholders at the opening of the company's liquidation shall have full power to realize the company's assets and pay its liabilities.

Once all the creditors of the company are paid, the liquidators will distribute the remaining proceeds to the company's shareholders on a pro-rata basis of their shareholding in the company.

  Under the Proposed Constitution, if Trinseo PLC is wound up and the assets available for distribution among the shareholders of Trinseo PLC are insufficient to repay the whole of the paid-up or credited as paid-up share capital, those assets are required to be distributed so that, as nearly as may be, the losses are borne by the shareholders of Trinseo PLC in proportion to the capital paid-up or credited as paid-up at the commencement of the winding up on the shares in Trinseo PLC held by them respectively. If in a winding-up the assets available for distribution among the Trinseo PLC shareholders are more than sufficient to repay the whole of the share capital paid-up or credited as paid-up at the commencement of the winding-up, the excess is required to be distributed among the shareholders in proportion to the capital at the commencement of the winding-up paid-up or credited as paid-up on the said Trinseo PLC shares held by them respectively. The position described above is subject to any special terms and conditions applying to any class of shares.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR"
THE ADVISORY VOTE ON THE IRISH CONSTITUTION PROPOSAL.

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Proposal 4—Advisory Proposals Concerning the Proposed Constitution of Trinseo PLC

In connection with the Merger, Trinseo S.A. is asking its shareholders, on a non-binding advisory basis, to vote upon proposals to approve certain governance provisions contained in the Proposed Constitution. These votes are not required by Luxembourg or Irish law, but pursuant to SEC guidance, Trinseo S.A. is required to submit these provisions to its shareholders to allow shareholders the opportunity to present their views on important governance provisions. The shareholder votes regarding these proposals are advisory votes, and are not binding on Trinseo S.A., Trinseo PLC or their respective boards of directors.

Each of the Advisory Constitution Proposals A-C below will be voted on separately. These votes are not contingent on approval

of the Irish Constitution Proposal. However, these proposals are conditioned on the approval of the Merger Proposal. If the Merger Proposal is not approved, these proposals will have no effect, even if approved by Trinseo S.A. shareholders.

We strongly encourage shareholders who vote in favor of the Merger Proposal and the Irish Constitution Proposal to also vote "for" these Advisory Constitution Proposals. In the judgement of the Trinseo S.A. Board, these provisions are necessary to adequately address the needs of Trinseo PLC following the Merger. Furthermore, the Merger is not conditioned on the separate approval of the Advisory Constitution Proposals.

Advisory Constitution Proposal A—Changes in Share Capital

The share capital in the Proposed Constitution has been reduced from the existing share capital under the Articles. The Board believes the share capital in the Proposed Constitution will provide adequate authorized share capital to (i) accommodate the issuance of Trinseo PLC ordinary shares (including giving effect to the Merger) and (ii) provide flexibility for future issuances of shares of Trinseo PLC if determined by the Trinseo PLC board of directors to be in the best interests of Trinseo PLC after the consummation of the Merger without incurring the risk, delay and potential expense incident to obtaining stockholder approval for a particular issuance.

Advisory
Constitution
Proposal



Current Articles

Proposed Constitution
Advisory Constitution Proposal A—Changes in Share Capital   The authorized share capital of the Company is up to USD $500,000,000 represented by 50,000,000,000 shares.

The Company's current issued share capital amounts to USD 487,779.34 represented by 48,777,934 ordinary shares. Each ordinary share is entitled to one vote.

Approximately 10.4 million ordinary shares are held in Treasury by Trinseo S.A. or a Luxembourg subsidiary.

The Company has no preferred shares authorized, issued and outstanding.

  The authorized share capital of Trinseo PLC is US$50,000,000 and €25,000, comprised of 4,000,000,000 ordinary shares, par value US$0.01 per share, 1,000,000,000 preferred shares, par value US$0.01 per share, and 25,000 deferred ordinary shares, par value €1.00 per share.

Immediately prior to completion of the Merger, Trinseo PLC will have an issued share capital of 25,000 deferred ordinary shares of €1.00 each, which shares were created solely to satisfy minimum statutory capital requirements that apply to all Irish public limited companies. Immediately following completion of the Merger, Trinseo PLC will have an issued share capital comprising such number of Trinseo PLC shares as will be equal to the number of Trinseo S.A. shares in issue immediately prior to completion of the Merger (excluding any treasury shares held by Trinseo S.A.), together with the 25,000 deferred ordinary shares. Each Trinseo PLC share will be entitled to one vote. The deferred ordinary shares will not be entitled to vote.

Advisory Constitution Proposal B—Change in Board's discretion to issue shares without waiver of preemptive rights

The Proposed Constitution provides the discretion to the board of directors, in accordance with Irish law, to issue additional shares for cash up to the authorized but unissued share capital (set forth above), without first offering those shares to existing shareholders. This provision represents a material change to the Board's discretion in the Articles. Following the Merger, although the Trinseo PLC Board

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PROPOSAL 4

will have increased discretion to issue shares, Trinseo PLC will remain subject to the rules regarding issuances of more than 20% of its share capital under certain circumstances, set by the NYSE.

Advisory
Constitution
Proposal



Current Articles

Proposed Constitution
Advisory Constitution Proposal B—Change in Board's discretion to issue shares   Luxembourg Law requires a shareholder vote to authorize the Board to issue any amount of its authorized share capital without preemptive rights (preferential subscription rights), for a period of up to 5 years.

In June 2018, shareholders approved authority for the Board to increase its existing share capital up to 20% without pre-emptive rights and up to 100% with pre-emptive rights, until June 2023.

An extraordinary resolution of shareholders, taken before a Luxembourg notary, is required to increase the authorized share capital.

  Under Irish law, the directors of a company may issue new ordinary or preferred shares without shareholder approval if authorized by shareholders or under its constitution. Shareholders may grant authorization for a maximum period of five years, at which point it must be renewed by the shareholders by an ordinary resolution. The Proposed Constitution authorizes the Trinseo PLC board to issue up to the maximum amount of its authorized but unissued share capital (set forth above), without approval from shareholders, for a period of five years from the date of adoption of the Proposed Constitution.

Under Irish law, certain statutory preemption rights apply automatically in favor of shareholders where shares are to be issued for cash. The Proposed Constitution will also permit the Trinseo PLC Board to disapply statutory preemptive rights in any issuance of shares, for a period of five years. The disapplication of preemptive rights must be renewed by shareholders at least every five years by 75% of votes cast at a general meeting of shareholders.

The Trinseo PLC Board will also be authorized to issue preferred shares with discretion as to the terms attaching to the preferred shares, including as to voting, dividend and conversion rights and priority relative to other classes of shares with respect to dividends and upon a liquidation.

Advisory Constitution Proposal C—Change in advance notice requirements for shareholder proposals

The Proposed Constitution provides the for a shorter notice period for which shareholders must present shareholder proposals to nominate directors, for inclusion at Trinseo PLC's next annual general meeting of shareholders. The Board believes this change brings the Proposed Constitution in line with most U.S.-traded public companies, and provides shareholders with a clearer deadline to submit such proposals, rather than a floating deadline tied to the date of the annual meeting.

Advisory
Constitution
Proposal



Current Articles

Proposed Constitution
Advisory Constitution Proposal C—Change in advance notice requirements for shareholder proposals   Shareholders may nominate board candidates between 120 and 90 days prior to the annual general meeting date and between 90 and 10 days prior to the extraordinary meeting date if such meeting has been called for purposes of electing one or more directors.   For nominations of directors or other business to be property brought before an annual general meeting, shareholders must submit notice within 90 to 120 days prior to the first anniversary of the prior year's proxy statement mailing.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR"
EACH OF THE ADVISORY VOTES ON THE IRISH PLC ARTICLES.

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Proposal 5—Distributable Profits Proposal

Under Irish law, Trinseo PLC may only pay dividends, make other distributions, or make share repurchases and redemptions from "distributable profits" shown in Trinseo PLC's unconsolidated financial statements prepared in accordance with the Irish Companies Act and filed with the Irish Companies Registration Office.

"Distributable profits" are the accumulated realized profits of Trinseo PLC that have not previously been utilized in a distribution or capitalization less its accumulated realized losses that have not previously been written off in a reduction or reorganization of capital, and include reserves created by way of a reduction of capital.

In addition, under Irish law, no dividend, distribution or share repurchase, or redemption may be paid, made or effected by Trinseo PLC unless the net assets of Trinseo PLC are equal to, or exceed, the aggregate of Trinseo PLC's called-up share capital plus its undistributable reserves and the relevant transaction does not reduce Trinseo PLC's net assets below such aggregate. "Undistributable reserves" include the undenominated capital, the capital redemption reserve fund and the amount by which Trinseo PLC's accumulated unrealized profits that have not previously been utilized by any capitalization exceed Trinseo PLC's accumulated unrealized losses that have not previously been written off in a reduction or reorganization of capital.

Immediately following the Merger, the unconsolidated balance sheet of Trinseo PLC will not contain any distributable profits and "shareholders' equity" on such balance sheet will be comprised entirely of "issued share capital" (equal to the aggregate nominal value of Trinseo PLC shares allotted and issued pursuant to the Merger) and "share premium" (equal to the amount paid-up on such Trinseo PLC shares in excess of the nominal value). You are being asked to approve the Distributable Profits Proposal, to enable, subject to the effectiveness of the Merger, the creation of

distributable profits of Trinseo PLC under Irish law by reducing the entire share premium of Trinseo PLC (or such lesser amount as may be approved by the Trinseo PLC Board) resulting from the allotment and issue of Trinseo PLC shares pursuant to the Merger, such that the reserve resulting from the cancellation of such share premium will be treated as distributable profits.

In addition to the approval of Trinseo S.A. shareholders, the Distributable Profits Proposal also requires the passing of a special resolution by the shareholders of Trinseo PLC (which will be passed by the existing shareholders prior to the Merger) and the approval of the Irish High Court. If the Distributable Profits Proposal is approved by Trinseo S.A. shareholders, Trinseo PLC intends to seek the approval of the Irish High Court for the Distributable Profits Proposal as soon as practicable following the Effective Date. Although Trinseo S.A. is not aware of any reason why the Irish High Court would not approve the Distributable Profits Proposal, such approval is a matter of judicial discretion and there is no guarantee that such approval will be forthcoming.

The Trinseo S.A. Board strongly recommends that shareholders vote for the Distributable Profits Proposal, to increase the likelihood that the proposal will be approved by the Irish High Court. If the Distributable Profits Proposal is not approved by Trinseo S.A. shareholders and the Irish High Court, Trinseo PLC will not be able to pay dividends, make other distributions or effect share repurchases and redemptions until such time as it has otherwise generated sufficient distributable profits from its operational activities following the Merger. However, passage of the Distributable Profits Proposal is not a condition to the Merger.

The Distributable Profits Proposal requires the approval of a majority of the shares represented in person or by proxy at the General Meeting. Broker non-votes will have no effect on the outcome of this proposal.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR"
APPROVAL OF THE CREATION OF DISTRIBUTABLE RESERVES.

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Proposal 6—Election of Directors

Trinseo's Board consists of twelve directors with one-year terms expiring in 2021. Each of the directors are elected for an annual term to serve until the next annual general meeting.

The persons named in the enclosed proxy will vote to elect K'Lynne Johnson, Joseph Alvarado, Frank Bozich, Jeffrey Cote, Pierre-Marie De Leener, Sandra Beach Lin, Jeanmarie Desmond, Matthew Farrell, Philip Martens, Donald Misheff, Henri Steinmetz and Mark Tomkins as directors unless the Proxy is marked otherwise. Each of the nominees has indicated his or her willingness to serve, if elected. However, if a nominee should be unable to serve, the ordinary shares represented by proxies may be voted for a substitute nominee designated by the Board. Management has no reason to believe that any of the above-mentioned persons will not serve his or her term as a director.

Our Board currently consists of 12 directors, the maximum number allowed under our Articles. If shareholders approve the Board Increase Proposal at the General Meeting, our Board size will be increased to 13 directors.

Half of our current directors have served on the Board for less than 4 years, while the average term of service of our directors is approximately 3.5 years.

We are committed to ongoing and regular board refreshment and succession planning. In 2020 two of our longest-tenured directors announced their retirement, and the Board appointed two new independent directors, Ms. Desmond and Mr. Farrell, to fill the vacancies. During 2020 the Board also named K'Lynne Johnson as its new Chair and appointed new chairs of its audit committee and nominating and corporate governance committee.

2021 Director Nominees

The individuals listed below have been nominated and are standing for election at this year's General Meeting. If elected, they will hold office until our 2022 annual general meeting of shareholders and until their successors are duly elected and qualified. Each of the nominees in this proposal was previously elected to the Board by shareholders, except Ms. Desmond and Mr. Farrell who were appointed by the Board to fill vacancies. Each of the nominees will cease to be directors if their respective appointments are not approved by a majority of the votes cast by our shareholders.

Director Nominee Skills

The following table highlights certain skills, knowledge and experience held by each current Director nominee. A particular Director may possess other skills, knowledge or experience even though they are not indicated below.

Director Nominee

Served
Since


Chemicals
Industry
Experience



Manufacturing/
Related Industry
Experience



Chief
Executive
Experience



Accounting
and Financial
Experience



Public
Company
Board
Experience
K'Lynne Johnson   2017   X       X       X
Joseph Alvarado   2017     X   X   X   X
Frank Bozich   2018   X   X   X       X
Jeffrey J. Cote   2014     X   X   X   X
Pierre-Marie De Leener   2014   X       X   X    
Jeanmarie Desmond   2020   X   X     X  
Matthew Farrell   2020   X   X   X   X   X
Sandra Beach Lin   2019   X   X   X     X
Philip R. Martens   2016       X   X       X
Donald T. Misheff   2015     X     X   X
Henri Steinmetz   2017   X       X        
Mark Tomkins   2019   X       X   X
Victoria Brifo (1)     X   X            
(1)
Shareholders may vote to elect Ms. Brifo in Proposal 7, which is subject to approval of the amendment to the Company's Articles in Proposal 2.

Board Commitment to Diversity

We seek nominees from diverse backgrounds with established strong professional reputations, sophistication, business acumen and experience in the global materials, chemical and related manufacturing industries. We also seek nominees with experience in substantive areas that are important to our business such as chemical industry expertise, international operations; accounting, finance and capital structure; strategic planning and operational leadership of complex organizations; human resources and development practices; and innovation. In addition, we believe that our nominees should possess the professional and personal qualifications necessary for board service, and we have highlighted particularly noteworthy attributes in each of the biographies of our directors and our nominees below. Twenty-five percent of our directors are women, and one of our directors self-identifies as a member of an underrepresented minority group

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(meaning an individual who self-identifies as Black or African American, Hispanic or Latinx, Asian, Native American or Alaska

Native, Native Hawaiian or Pacific Islander). Two of our directors are non-U.S. citizens and one director maintains dual citizenship.

GRAPHIC   GRAPHIC   GRAPHIC

The election of each director requires the approval of a majority of the shares represented in person or by proxy at the General Meeting. Broker non-votes will have no effect on the outcome of this proposal.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE "FOR"
THE ELECTION OF EACH OF THE NOMINEES AS DIRECTOR.

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2021 Director Nominees

GRAPHIC K'lynne Johnson
Age: 52
Director Since: March 2017
Committee Membership:

Compensation and Talent Development (Chair)

Nominating & Corporate Governance

Professional Experience:

Ms. Johnson served as President and Chief Executive Officer of Elevance Renewable Sciences Inc., a specialty chemicals company, from 2007 to 2015, and as Chairwoman from 2015 to 2016. Ms. Johnson joined Elevance after over 20 years' experience working within the oil and petrochemicals industry for Amoco Corporation and BP p.l.c. (joining BP after its merger with Amoco in 1998). During this time she held both operational and functional roles, culminating in her role as Senior Vice President of Global Derivatives within BP's global Innovene business, which included P&L accountability for multiple global commodity and specialty chemicals businesses. Ms. Johnson also served as director of TPC Group, a manufacturer of products derived from petrochemical raw materials, from 2011 to 2012 before the company was taken private.

Education:

Ms. Johnson graduated from Brigham Young University with a degree in Management and Organizational Behavior (M.O.B.) and a B.S. in Psychology.

Other Public Company Directorships:

Current Directorships—
FMC Corporation (NYSE: FMC) since 2013

Director Qualifications:

Ms. Johnson brings to our Board valuable experience in operational leadership and chemical industry and technological expertise.

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GRAPHIC Joseph Alvarado
Age: 68
Director Since: March 2017
Committee Membership:

Audit

Environmental, Health, Safety, Sustainability & Public Policy

Professional Experience:

Mr. Alvarado served as Chief Executive Officer of Commercial Metals Company (NYSE: CMC), a global manufacturer, recycler and marketer of steel and other metals, from September 2011 until September 2017, and as Chairman of CMC's board of directors from January 2013 until January 2018. He joined CMC in April 2010 as Executive Vice President and Chief Operating Officer, was named President and Chief Operating Officer in April 2011, and became President and Chief Executive Officer in September 2011 until his retirement. Prior to joining CMC, he was President and Chief Operating Officer of Lone Star Technologies, Inc. from 2004 to 2007. In June 2007, following the acquisition of Lone Star Technologies, Inc. by United States Steel Corporation, Mr. Alvarado was named President of U.S. Steel Tubular Products, Inc., a division of United States Steel Corporation, a position he held until March 2009. Mr. Alvarado began his career at Inland Steel Company in 1976 and spent 21 years with the company in roles of increasing responsibility. He then served in executive roles with Birmingham Steel Corporation and Ispat North America Inc. until joining Lone Star Technologies.

Education:

Mr. Alvarado has an MBA from Cornell University and a B.A. degree in Economics from University of Notre Dame.

Other Public Company Directorships:

Current Directorships—
Kennametal Inc. (NYSE: KMT) since January 2018
Arcosa, Inc. (NYSE: ACA) since November 2018
PNC Financial Services Group Inc. (NYSE: PNC) since January 2019

Past Directorships—
Commercial Metals Company (NYSE: CMC) from 2013 to January 2018
Spectra Energy Corp (NYSE: SE) from 2011 until February 2017

Director Qualifications:

Mr. Alvarado brings years of experience in a cyclical commodities-driven industry and significant perspective on global manufacturing operations and strategic planning.

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GRAPHIC Frank A. Bozich
Age: 60
Director Since: June 2019
Committee Membership:

Environmental, Health, Safety, Sustainability & Public Policy

Professional Experience:

Mr. Bozich became the Company's President and Chief Executive Officer in March 2019. From May 2013 until February 2019, Mr. Bozich had been the President and Chief Executive Officer at the SI Group, Inc., a leading global developer and manufacturer of phenolic resins and chemicals used in the production of antioxidants, engineering plastics, fuels and lubes, rubber and pharmaceutical ingredients. Prior to SI Group Inc., Mr. Bozich held several executive management positions at BASF Corporation, a multi-national chemicals and manufacturing corporation, including President of BASF's Catalysts Division from 2010 to 2013, Group Vice President of Precious and Base Metal Service, and Group Vice President of the Integration Management Office. Prior to BASF, Mr. Bozich was Group Vice President, Enterprise Technologies and Ventures at Engelhard Corporation, which was acquired by BASF in 2006. He has also held leadership positions at Rohm and Haas; Croda Adhesives, Inc.; and Apex Adhesives, which he founded in 1986.

Education:

Mr. Bozich holds a bachelor's degree in Chemistry and a master's degree in Business Administration from the University of Chicago, as well as a master's degree in Chemistry from the University of Illinois.

Other Public Company Directorships:

Current Directorships—
OGE Energy Corp (NYSE: OGE) since February 2016

Director Qualifications:

Mr. Bozich is an accomplished CEO known for his strong personal leadership and track record of driving business growth and corporate transformation. His breadth of experience in leading chemical businesses in diverse and dynamic global markets is well-suited for the Company's strategic priorities.

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PROPOSAL 6

GRAPHIC Jeffrey J. Cote
Age: 54
Director Since: May 2014
Committee Membership:

Audit

Compensation and Talent Development

Professional Experience:

Mr. Cote has served as the Chief Executive Officer and President of Sensata Technologies Holding plc (NYSE: ST) since March 2020. Prior to his appointment as CEO, Mr. Cote served as President and as Chief Operating Officer of Sensata since July 2012 and as Executive Vice President of its Global Sensing Solutions business since November 2015. He joined Sensata as Senior Vice President and Chief Financial Officer in January 2007 and was appointed Executive Vice President in July 2007. From March 2005 to December 2006, Mr. Cote was Chief Operating Officer of the law firm Ropes & Gray. From January 2000 to March 2005, Mr. Cote was Chief Operating, Financial and Administrative Officer of Digitas. Previously he worked for Ernst & Young LLP from 1989 until 1997. Mr. Cote is a certified public accountant.

Education:

Mr. Cote received a B.A. degree in Business Administration and a Master of Accounting from Florida Atlantic University.

Other Public Company Directorships:

Current Directorships—
Sensata Technologies Holding plc (NYSE: ST) since March 2020

Director Qualifications:

Mr. Cote brings significant management, financial and accounting experience to our Board.

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PROPOSAL 6

GRAPHIC Pierre-Marie De Leener
Age: 63
Director Since: May 2014
Committee Membership:

Audit

Environmental, Health, Safety, Sustainability & Public Policy

Professional Experience:

Mr. De Leener served as interim CEO of Braas Monier Building Group SA from January 2016 to November 2016 and as Chairman of its Board of Directors from June 2014 to March 2017. Prior to that, he served as Executive Vice President for PPG Industries, Inc. from July 2010 until December 2012. From June 2008 until August 2011, Mr. De Leener also served as President of PPG Europe S.A. and as Chief Executive Officer of SigmaKalon Group from 1998 until January 2008.

Education:

Mr. De Leener received a B.S. degree in Economics and Philosophy and a Master of Chemical Engineering degree from Catholic University of Louvain, Belgium.

Other Public Company Directorships:

None

Director Qualifications:

Mr. De Leener brings valuable executive management and chemical industry experience to our Board.

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PROPOSAL 6

GRAPHIC Jeanmarie Desmond
Age: 54
Director Since: October 2020
Committee Membership:

Audit

Compensation and Talent Development

Professional Experience:

Ms. Desmond is the former Executive Vice President and Chief Financial Officer of DuPont de Nemours, Inc. and has previously served as Vice President and Co-Controller for DowDuPont and as finance leader for the Specialty Products division following the merger of DuPont with Dow Chemical. Ms. Desmond served in various leadership roles within DuPont in her 30-year career with the company. She also serves on the board and is treasurer of Delaware Prosperity Partnership, a public-private partnership overseeing economic development in Delaware.

Education:

Ms. Desmond received a B.S. in Accounting from Mt. St. Mary's University and is a certified public accountant (inactive).

Other Public Company Directorships:

Current Directorships—
IPG Photogenics Corporation (Nasdaq: IPGP) since 2021

Director Qualifications:

Ms. Desmond brings substantial finance and accounting experience and extensive experience in the chemicals industry to our Board.

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PROPOSAL 6

GRAPHIC Matthew Farrell
Age: 64
Director Since: November 2020
Committee Membership:

Compensation and Talent Development

Nominating and Corporate Governance

Professional Experience:

Mr. Farrell is the Chairman, President and Chief Executive Officer of Church & Dwight Co. Inc. ("Church & Dwight"), serving since 2016 and as Chairman since 2019. Mr. Farrell served as Executive Vice President, Chief Financial Officer and Chief Operating Officer at Church & Dwight since 2014, and as Chief Financial Officer since 2006. Prior to that, Mr. Farrell served as Chief Financial Officer of Alpharma Inc., as Vice President, Investor Relations & Communications at Ingersoll-Rand Ltd., and in various senior financial positions at AlliedSignal Inc. Mr. Farrell began his career with KPMG Peat Marwick LLP, where he was an audit partner.

Education:

Mr. Farrell received a B.S. degree from Manhattan College and is a certified public accountant (inactive).

Other Public Company Directorships:

Current Directorships—
Church & Dwight Co. Inc. (NYSE: CHD) since 2019
Lydall Co., Inc. (NYSE: LDL) since 2003*

Director Qualifications:

Mr. Farrell brings to our Board his experience as a chief executive officer, substantial financial and audit expertise and experience in the chemicals, industrial goods and consumer products industries.

   


*
In September 2020, Mr. Farrell informed the Lydall board of directors of his intention not to stand for reelection as a director at Lydall's next annual meeting of shareholders, to be held on April 20, 2021.

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PROPOSAL 6

GRAPHIC Sandra Beach Lin
Age: 63
Director Since: November 2019
Committee Membership:

Compensation and Talent Development

Nominating & Corporate Governance

Professional Experience:

From 2010 to 2011, Ms. Beach Lin was President and Chief Executive Officer of Calisolar, Inc., a manufacturer of solar silicon and multicrystalline solar cells. Prior to joining Calisolar, she was Executive Vice President, then Corporate Executive Vice President, at Celanese Corporation, a global technology and specialty materials company, from 2007 to 2010. Ms. Beach Lin joined Avery Dennison Corporation, a global leader in pressure-sensitive adhesives technology as Group Vice President from 2005 to 2007. Prior to joining Avery Dennison, from 2002 to 2005, she was President, Alcoa Closure Systems International, a division of Alcoa Incorporated, a global aluminum leader. From 1994 to 2001, Ms. Beach Lin held various executive positions at Honeywell International.

Education:

Ms. Beach Lin graduated with a BBA in General Management from the University of Toledo and has an MBA in Marketing and Policy and Control from the University of Michigan.

Other Public Company Directorships:

Current Directorships—
American Electric Power (NYSE: AEP) since 2012
Avient Corp. (NYSE: AVNT) since 2013

Past Directorships—
WESCO International (NYSE: WCC) from 2002 to 2019

Director Qualifications:

Ms. Beach Lin brings to our Board her experience as a chief executive officer and extensive experience in the global specialty chemicals industry.

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PROPOSAL 6

GRAPHIC Philip R. Martens
Age: 61
Director Since: September 2016
Committee Membership:

Compensation

Nominating & Corporate Governance (Chair)

Professional Experience:

From February 2011 to April 2015, Mr. Martens served as President and Chief Executive Officer of Novelis, Inc., a leader in aluminum rolled products and can recycling with worldwide operations. He joined Novelis as President and Chief Operating Officer in April 2009. Prior to his employment with Novelis, Mr. Martens served as Senior Vice President of light vehicle systems for ArvinMeritor Inc., a distributor for engine and transmission parts and President and Chief Executive Officer designate of Arvin Innovation, a leading global provider of dynamic motion and control automotive systems. From 1987 to 2005, Mr. Martens held various product development and engineering roles at Ford Motor Company, including his most recent role as a Group Vice President of product creation from 2003 to 2005.

Education:

Mr. Martens has an MBA from University of Michigan and received his B.S. degree in mechanical engineering from Virginia Polytechnic Institute.

Other Public Company Directorships:

Current Directorships—
Graphic Packaging Holding Company (NYSE: GPK) since 2013

Past Directorships—
Plexus Corporation (NASDAQ: PLXS) from 2010 until February 2017

Director Qualifications:

Mr. Martens brings to the Board significant leadership and management experience in global manufacturing operations, along with innovation expertise.

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PROPOSAL 6

GRAPHIC Donald T. Misheff
Age: 64
Director Since: February 2015
Committee Membership:

Audit

Nominating & Corporate Governance

Professional Experience:

Mr. Misheff served as managing partner from 2003 until his retirement in 2011 of the Northeast Ohio offices of Ernst & Young LLP, a public accounting firm. As the managing partner, Mr. Misheff advised many of the region's largest companies on financial and corporate governance issues. He began his career with Ernst & Young LLP in 1978 as part of the audit staff and later joined the tax practice, specializing in accounting/financial reporting for income taxes, purchase accounting, and mergers and acquisitions. He has more than 30 years of experience performing, reviewing, and overseeing the audits of financial statements of a wide range of public companies.

Education:

Mr. Misheff graduated from the University of Akron with a B.S. in Accounting.

Other Public Company Directorships:

Current Directorships—
TimkenSteel Corporation (NYSE: TMST) since 2014
First Energy Corp. (NYSE: FE) since 2012

Director Qualifications:

Mr. Misheff brings extensive financial, accounting and public company corporate governance experience to our Board.

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PROPOSAL 6

GRAPHIC Henri Steinmetz
Age: 64
Director Since: November 2017
Committee Membership:

Nominating & Corporate Governance

Environmental, Health, Safety, Sustainability & Public Policy

Professional Experience:

From 2016 to 2018, Mr. Steinmetz served as Chief Executive Officer of the Ceramtec Group, a global supplier of advanced ceramics. From 2009 to 2016, Mr. Steinmetz was Executive Director and Chief Executive Officer of Ruetgers N.V., Europe's leading manufacturer of chemical raw materials made from coal tar. Prior to joining Ruetgers, Mr. Steinmetz was President of Sulzer Metco, a worldwide technology leader in coating materials, from 2004 to 2008, and was an Executive Vice President at Great Lakes Chemical Corporation from 2000 to 2004.

Education:

Mr. Steinmetz graduated with a M.S. in metallurgy from the Technical University Clausthal, Germany and has an MBA from INSEAD Fontainebleau, France.

Other Public Company Directorships:

None

Director Qualifications:

Mr. Steinmetz brings significant global chief executive officer experience and decades of chemical industry experience to our Board.

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PROPOSAL 6

GRAPHIC Mark Tomkins
Age: 65
Director Since: November 2019
Committee Membership:

Audit (Chair)

Environmental, Health, Safety, Sustainability & Public Policy

Professional Experience:

From 2005 to 2006, Mr. Tomkins was Senior Vice President and Chief Financial Officer of Innovene, at the time, a leading petrochemical and polymers company. Prior to joining Innovene, Mr. Tomkins was Senior Vice President, Chief Financial Officer and Treasurer of Vulcan Materials, a building materials and chemical company, from 2001 to 2005. He joined Great Lakes Chemical Corp., a chemical research, production, sales and distribution company as Senior Vice President and Chief Financial Officer from 1998 to 2001. Prior to Great Lakes Chemical, Mr. Tomkins was Vice President of Finance and Business Development for Polymers and Vice President of Finance and Business Development for Electronic Materials at Allied Signal (now Honeywell International). Mr. Tomkins' previous experience includes service as a director of CVR Energy, Inc., a publicly traded company primarily engaged in petroleum refining and nitrogen fertilizer manufacturing, from 2007 to 2012, as well as a director of private companies in the energy and plastics sectors.

Education:

Mr. Tomkins graduated with a B.S. in Finance and Quantitative Management, has an MBA from Eastern Illinois University and is a certified public accountant.

Other Public Company Directorships:

Current Directorships—
Terminix Global Holdings (NYSE: TMX) since 2015
WR Grace & Co. (NYSE: GRA) since 2006

Director Qualifications:

Mr. Tomkins brings significant financial, accounting and management expertise, along with extensive experience on other public and private company boards to Trinseo's Board.

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PROPOSAL 7

Proposal 7—Election of Director

Conditioned upon shareholder approval of Proposal 2, the Board has nominated Victoria Brifo as its nominee for Director. The persons named in the enclosed proxy will vote to elect Ms. Brifo as director unless the Proxy is marked otherwise. Ms. Brifo has indicated her willingness to serve, if elected, and should she be unable to serve, the ordinary shares represented by proxies may be voted for a substitute nominee designated by the Board. Management has no reason to believe that she will not serve her term as a director. If elected, Ms. Brifo will hold office until our 2022 annual general meeting of shareholders and until her successor is duly elected and qualified. Ms. Brifo will not be elected director if her appointment is not approved by a majority of the shares represented in person or by proxy at the General Meeting. Broker non-votes will have no effect on the outcome of this proposal.

GRAPHIC

Victoria Brifo

Age: 52

Professional Experience:

Victoria Brifo is Senior Vice President and Chief Human Resources Officer at Air Products and Chemicals, Inc. (NYSE: APD). She is responsible for leading all aspects of the company's Human Resources (HR) organization, including HR Operations, Diversity and Inclusion, Talent Management, and Compensation and Benefits, as well as Global Health and Wellness, and Corporate Aviation and Corporate Transportation. Ms. Brifo has been with Air Products since 2001, starting as a production site leader and progressing through several plant leadership positions before becoming Global Diversity Director in 2005. In 2008 she was named Global Manager of Electronics Operations and moved to the Merchant Gases group in 2011 to lead the Global Generated Gases business. In 2014 Ms. Brifo assumed the role of Global Transformation Leader for Industrial Gases. She was subsequently appointed Vice President, Global Gases, followed by Vice President, Equipment Sales, Plant Support and Central Procurement. Prior to joining Air Products, Ms. Brifo worked at LyondellBasell and Amoco Production Company.

Education:

Ms. Brifo holds degrees in chemical engineering and political science from the Massachusetts Institute of Technology.

Other Public Company Directorships:

None

Director Qualifications:

Ms. Brifo brings significant experience in the chemicals and manufacturing industry, as well as leadership, management and human resources expertise to our board of directors.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR"
THE ELECTION OF VICTORIA BRIFO AS DIRECTOR.

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CORPORATE GOVERNANCE

Corporate Governance

Board Nominees.    Under its charter, our nominating and corporate governance committee is responsible for recommending to the Board candidates to stand for election to the Board at the Company's annual general meeting of shareholders and for recommending candidates to fill vacancies on the Board that may occur between annual general meetings. It is the policy of the Board that directors should possess the highest personal and professional ethics, integrity and values. Board members are expected to become and remain informed about the Company, its business and its industry and rigorously prepare for, attend and participate in all Board and applicable committee meetings. The committee evaluates each individual in the context of the Board as a whole, with the objective of recommending a group that can best perpetuate the success of our business and represent shareholders' interests through the exercise of sound judgment using its diversity of experience. In addition, the Board considers, in light of our business and Board composition, each director nominee's experience, qualifications, attributes and skills that are identified in the biographical information contained under Proposal 6 and Proposal 7.

The nominating and corporate governance committee considers properly submitted recommendations for candidates to the Board from shareholders. Any shareholder may submit in writing nominations of persons for consideration for each shareholder meeting at which directors are to be elected by not later than the 90th calendar day nor earlier than the 120th calendar day before the date of the annual general meeting. Any shareholder recommendations for consideration by the Board should include the candidate's name, biographical information, information regarding any relationships between the candidate and the shareholder within the last three years, a statement of recommendation of the candidate from the shareholder, a description of our shares beneficially owned by the shareholder, a description of all arrangements between the candidate and the recommending shareholder and any other person pursuant to which the candidate is being recommended, a written indication of the candidate's willingness to serve on the Board, any other information required to be provided under securities laws and regulations, and a written indication to provide such other information as the Board may reasonably request. Recommendations should be sent to Angelo N. Chaclas, Corporate Secretary, Trinseo S.A., 1000 Chesterbrook Boulevard, Suite 300, Berwyn, PA 19312. The Board evaluates candidates for the position of director recommended by shareholders or others in the same manner as candidates from other sources. The Board will determine whether to interview any candidates and may seek additional information about candidates from third-party sources. As part of its ongoing succession planning, the Company seeks to identify potential Board nominees on behalf of the Board that meet the Board's requirements with respect to diversity, experience, skill, and qualifications.

Board Independence.    Our Corporate Governance Guidelines provide that our Board shall consist of such number of directors who are independent as is required and determined in accordance with applicable laws and regulations and requirements of the NYSE. The Board evaluates any relationships of each director and nominee with Trinseo and makes an affirmative determination whether or not such director or nominee is independent. Under our Corporate Governance Guidelines, an "independent" director is one who meets the qualification requirements for being an independent director under applicable laws and the corporate governance listing standards of the NYSE. Our Board reviews any transactions and relationships between each director or any member of his or her immediate family and Trinseo. The purpose of this review is to determine whether there were any such relationships or transactions and, if so, whether they were inconsistent with a determination that the director was independent. The Company maintains a related party transactions policy and conflict of interest policy, as discussed below under "Related Party Transactions." As a result of its review, our Board has affirmatively determined that all of our current directors and nominees, except for our CEO and President, Frank Bozich, are independent under the governance and listing standards of the NYSE.

Diversity and Board Expertise.    We believe that diversity considerations are an important element, among many, when identifying director nominees who will best serve the needs of the Company and the interests of our shareholders. These diversity considerations enable us to provide sound and prudent guidance by developing a Board with a diverse range of talents, ages, skills, character, expertise, professional experiences, and backgrounds.

Risk Oversight.    Risk is inherent in every material business activity that we undertake. Our business exposes us to strategic, credit, market, compliance, operational and reputational risks. To support our corporate goals and objectives, risk appetite, and business and risk strategies, we maintain a governance structure that delineates the responsibilities for risk management activities, and the governance and oversight of those activities, between management and our Board. The Board is committed to strong, independent oversight of management and risk through a governance structure that includes other Board committees. Under our structure, it is management's responsibility to manage risk and bring to the Board's attention risks that are material to Trinseo. The Board has oversight responsibility for the systems established to report and monitor the most significant risks applicable to Trinseo. The Board administers its risk oversight role directly and through its committee structure and the committees' regular reports to the Board at Board

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meetings. The Board divides its risk oversight responsibilities between itself and its committees by having each review or assess key issues or areas of responsibility as follows:

Board of Directors  

Strategic, financial, and execution risks and exposures associated with our annual and multi-year business plans

Acquisitions and divestures

Capital expenditure and budget planning

Major litigation, investigations, and other matters that present material risk to our operations, plans, prospects, or reputation

Review of enterprise risk management including cybersecurity and information security risk oversight

Audit Committee  

Risks associated with financial accounting matters, including financial reporting, accounting, disclosure, and internal controls over financial reporting

Supervision and selection of our external and internal auditors

Our ethics and compliance programs

Compensation Committee  

Risks related to the design of our executive compensation programs, plans, and arrangements

Senior management succession planning

Nominating and Corporate Governance Committee  

Risks related to our governance structures and processes

Director succession planning

Environmental, Health, Safety, Sustainability and Public Policy Committee  

Our environmental, health and safety risk management programs

The alignment of our environmental, health, safety, sustainability, social and public policy program with the Company's business strategy and creation of stakeholder value

Board Leadership Structure.    Under our Corporate Governance Guidelines, our Board may select a Chair of the Board at any time, who may also be an executive officer of the Company. The Board has chosen to separate the roles of Board Chair and Chief Executive Officer, which the Board believes is currently in the best interest of Trinseo and its shareholders. This structure permits our Chief Executive Officer to devote his attention to leading Trinseo and to executing on our business strategy.

Ms. Johnson is our current non-executive Chair of the Board and has served as a director since 2017. Ms. Johnson brings significant experience as Chair, including, but not limited to: (i) entrepreneurial and senior public company experience; (ii) expertise in environmental, social and governance issues; and (iii) strategic transformation experience. Ms. Johnson has significant experience in the specialty chemical industry and as a public company director. As described above, the Board has determined that Ms. Johnson meets the definition of an independent director under NYSE listing standards. Following the General Meeting, the Board will meet to adjust committee assignments as necessary.

Board Attendance.    We expect our Board members to prepare for, attend and participate in all Board and applicable committee meetings. Our Board held nine meetings in 2020. The audit, compensation, and nominating and corporate governance committees held nine, six and five meetings in 2020, respectively. No Board member attended less than 75% of our Board and committee meetings, as applicable, in 2020.

Due to the travel restrictions and stay-at-home orders in the U.S., Luxembourg and elsewhere during the COVID-19 pandemic, our full Board has not traveled to Luxembourg to attend meetings in person. Like many companies, we continue to hold board meetings via video conference and intend to do so until travel restrictions are lifted, and health and safety concerns have been alleviated.

We do not have a policy for the attendance of our directors at our annual general meeting of shareholders. In 2020 four directors and no shareholders attended our annual general meeting, which was held via teleconference pursuant to guidance from the Grand Duchy of Luxembourg. Under Luxembourg law, we are required to receive notice by the meeting's record date of a shareholder's intention to attend the annual general meeting of shareholders. In 2020 we allowed eligible shareholders to attend the teleconference by registering on our voting website. This year's General Meeting will once again be held via teleconference, using the same registration method for shareholders who wish to attend. We fully intend to resume holding future annual general meetings of shareholders in person, once it is possible for all participants to attend safely.

Executive Sessions.    Our Corporate Governance Guidelines provide that the non-management directors of the Board meet in executive session at least once during each regularly scheduled Board meeting to review matters concerning the relationship of the Board with the management directors and other members of senior management and such other matters as it deems appropriate. Additionally, the Board is required to have least one executive session annually of its independent directors. Ms. Johnson acts as the chair of these executive sessions.

Board Annual Performance Reviews.    Pursuant to our Corporate Governance Guidelines the Board annually conducts a self-evaluation of the Board as a whole. In accordance with the written charters of our audit, compensation and nominating and

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corporate governance committees, we also evaluate each committee's performance on an annual basis and report to the Board the findings.

Code of Business Conduct.    We have adopted a written Code of Business Conduct applicable to all directors, officers and employees and a written Code of Ethics for Senior Financial Employees, applicable to our Chief Executive Officer, Chief Financial Officer, Treasurer, Principal Accounting Officer, Controller, and all employees performing similar functions. These policies are designed to maintain the integrity of our business and financial reporting. These codes cover, among other things, professional conduct, conflicts of interest, accurate recordkeeping and reporting, public communications and the protection of confidential information, as well as adherence to laws and regulations applicable to the conduct of our business. Copies of these codes can be found under the "Corporate Governance" tab on the Investor Relations section of our website, www.investor.trinseo.com by selecting the "Ethics and Compliance" link and then "supporting policies."

Corporate Governance Guidelines.    We have adopted Corporate Governance Guidelines that outline the Board's governance policies and practices. The current version of our Corporate Governance Guidelines can be found under the "Corporate Governance" tab on the Investor Relations section of our website, www.investor.trinseo.com by selecting the "Ethics and Compliance" link and then "supporting policies."

Communications with Directors.    Shareholders and other interested parties may communicate directly with the Board, the non-management directors or the independent directors as a group, or specified individual directors by writing to such individual or group c/o Corporate Secretary, Trinseo S.A., 1000 Chesterbrook Boulevard, Suite 300, Berwyn, PA 19312. The Corporate Secretary will forward such communications to the relevant group or individual at or prior to the next meeting of the Board. The Board has instructed our Corporate Secretary to review the correspondence prior to forwarding it, and in his discretion, not to forward certain items if he deems them to be of a commercial or frivolous nature or otherwise inappropriate for the Board's consideration. In these cases, he may forward some of the correspondence elsewhere in the Company for review and possible response.

Luxembourg Corporate Governance.    As a Luxembourg company, we are subject to laws that can significantly restrict our Board's ability to grant certain rights to shareholders under our Articles. For example, Luxembourg law:

    Imposes a supermajority requirement in order to amend our Articles, which cannot be amended by the Board or our shareholders;

    Prohibits a plurality carve out from our majority voting requirement in a contested director election; and

    Requires shareholder action by written consent in lieu of a meeting to be unanimous.

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BOARD STRUCTURE AND COMMITTEE COMPOSITION

Board Structure and Committee Composition

We have a standing audit committee, compensation and talent development committee and a nominating and corporate governance committee with the composition and responsibilities described below. Each committee operates under a charter that has been approved by our Board. A copy of each charter can be found by clicking on "Corporate Governance" and then "Committee Composition" in the Investor Relations section of our website, www.investor.trinseo.com. The members of each committee are appointed by the Board and each member serves until his or her successor is elected and qualified, unless he or she is earlier removed or resigns. In addition, from time to time, special committees may be established under the direction of the Board when necessary to address specific issues.

The table below provides information about the membership of our standing audit, compensation and talent development, nominating and corporate governance and our and environmental, health, safety, sustainability and public policy committees during fiscal 2020:

Name

Audit

Compensation and
Talent Development


Nominating and
Corporate Governance


Environmental, Health,
Safety, Sustainability
and Public Policy
K'Lynne Johnson †       Chair   X    
Joseph Alvarado   X       X
Frank Bozich               Chair
Jeffrey J. Cote §   X   X    
Pierre-Marie De Leener   X           X
Jeanmarie Desmond §   X   X    
Matthew Farrell §       X   X    
Sandra Beach Lin     X   X  
Philip R. Martens       X   Chair*    
Donald T. Misheff §   X     X  
Mark Tomkins §   Chair*           X
Denotes Board chair.

§
Denotes Audit Committee Financial Expert

*
Since November 2020.

Audit Committee

The purpose of the audit committee is set forth in the audit committee charter. The audit committee's primary duties and responsibilities are to:

    Appoint or replace, compensate and oversee the outside auditors for the purpose of preparing or issuing an audit report or related work or performing other audit, review or attest services for us and will report directly to the audit committee.

    Pre-approve all auditing services and permitted non-audit services (including the fees and terms thereof) to be performed for us by our outside auditors, which are approved by the audit committee prior to the completion of the audit.

    Review and discuss with management and the outside auditors the annual audited and quarterly unaudited financial statements, our disclosures under "Management's Discussion and Analysis of Financial Condition and Results of Operations", and the selection, application and disclosure of critical accounting policies and practices used in such financial statements.

    Review and approve all related party transactions as defined under Item 404(a) of Regulation S-K.

    Discuss with management and the outside auditors significant financial reporting issues and judgments made in connection with the preparation of our financial statements, including any significant changes in our selection or application of accounting principles, any major issues as to the adequacy of our internal controls and any special steps adopted in light of material control deficiencies.

A copy of the charter, which satisfies the applicable standards of the SEC and the NYSE is available on our website. The audit committee currently consists of Joseph Alvarado, Jeffrey J. Cote, Pierre-Marie De Leener, Jeanmarie Desmond, Donald T. Misheff and Mark Tomkins. Our Board has determined that Ms. Desmond and each of Messrs. Alvarado, Cote, De Leener, Farrell, Misheff and Tomkins are independent directors pursuant to Rule 10A-3(b)(1) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and Section 303A.02 of the New York Stock Exchange Listed Company Manual. Ms. Desmond and each of Messrs. Cote, Farrell, Misheff and Tomkins is also an "audit committee financial expert" within the meaning of Item 407(d)(5) of Regulation S-K. Mr. Tomkins also serves as chair of the audit committee.

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Compensation & Talent Development Committee

The purpose of the compensation and talent development committee (the "compensation committee") is to assist the Board in fulfilling its responsibilities relating to oversight of the compensation of our directors, executive officers and other employees and the administration of our benefits and equity-based compensation programs. The compensation committee reviews and recommends to our Board compensation plans, policies and programs and approves specific compensation levels for all executive officers. The compensation committee currently consists of Jeffrey J. Cote, Jeanmarie Desmond, Matthew Farrell, K'Lynne Johnson, Sandra Beach Lin and Philip R. Martens. Ms. Johnson serves as chair of the compensation committee. A copy of its charter, which satisfies the applicable standards of the SEC and the NYSE, is available on our website. Pursuant to its charter, the compensation committee may delegate to subcommittees of the compensation committee any of the responsibilities of the full committee.

Nominating and Corporate Governance Committee

The purpose of the nominating and corporate governance committee is to (i) identify, screen and review individuals qualified to serve as directors (consistent with criteria approved by our Board) and recommend to our Board candidates for nomination for election at the annual meeting of shareholders or to fill Board vacancies or newly created directorships; (ii) develop and recommend to our Board and oversee the implementation of our corporate governance guidelines; (iii) oversee evaluations of our Board and (iv) recommend to our Board candidates for appointment to board committees. The nominating and corporate governance committee currently consists of Matthew Farrell, K'Lynne Johnson, Sandra Beach Lin, Philip R. Martens, Donald T. Misheff and Henri Steinmetz. Mr. Martens serves as chair of the nominating and corporate governance committee. Our Board has adopted a written charter under which the nominating and corporate governance committee operates, which is available on our website.

Environmental, Health, Safety, Sustainability and Public Policy Committee

The Environmental, Health, Safety, Sustainability and Public Policy Committee (the "EHSS&PP Committee") was established in 2014, for the purpose of assisting the Board in fulfilling its oversight responsibilities by assessing the effectiveness of programs and initiatives that support the environment, health and safety, sustainability, corporate social responsibility and climate change ("Sustainability") policies and programs of the Company. Its duties and responsibilities are to:

    Support alignment between the Company and the Board on the Company's Sustainability, social, and public policy goals;

    Guide the Company on its Sustainability programs, policies, partnerships, activities and goals to ensure consistency with and impact upon the Company's business strategy and the creation of stakeholder value and relationships;

    Review of external public policy/governmental affairs issues and trends in order to more effectively achieve the Company's business goals, and provide recommendations to the Board regarding the Company's response to these issues consistent with applicable legal and regulatory requirements;

    Review, approve and recommend to the Board for adoption, the Company's annual public Sustainability and Corporate Social Responsibility Report; and

    Assist the Board in fulfilling its oversight responsibility for the Company's risk management programs by assessing risks that may arise in connection with the Company's Sustainability, programs, partnerships, activities and goals.

The EHSS&PP Committee currently consists of Joseph Alvarado, Frank A. Bozich, Pierre-Marie De Leener, Henri Steinmetz and Mark Tomkins. Mr. Bozich serves as chair of the EHSS&PP Committee. A copy of its charter is available on the Company's website.

Compensation Committee Interlocks and Insider Participation

None of our executive officers serves as a member of the Board or the compensation committee of any other company that has any executive officers serving as a member of our Board or compensation committee.

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OUR COMPANY'S EXECUTIVE OFFICERS

Our Company's Executive Officers

Biographical information concerning our President and Chief Executive Officer, Frank A. Bozich, who is a nominee to our Board, is set forth above under Proposal 6.

David Stasse, Executive Vice President and Chief Financial Officer. Mr. Stasse, age 50, was named Executive Vice President and Chief Financial Officer in July 2019. Mr. Stasse joined the Company in July 2013 as Vice President and Treasurer with responsibility for all treasury matters, including cash management, risk management, relationships with rating agencies and commercial banks, and financing matters. During his tenure he added responsibility for Investor Relations and Corporate Finance for the Company. Prior to joining Trinseo, Mr. Stasse was employed by Freescale Semiconductor, Inc., a global semiconductor manufacturer that served the automotive, networking, consumer and industrial markets, where he served as Vice President and Treasurer from 2008 to 2013. Mr. Stasse holds an MBA in Finance from the University of Maryland and a Bachelor of Science degree in Business Logistics from Penn State University.

Angelo N. Chaclas, Senior Vice President, Chief Legal Officer, Chief Compliance Officer and Corporate Secretary. Mr. Chaclas, age 57, has been the Company's Chief Legal Officer, Senior Vice President, and Corporate Secretary since January 2015. Mr. Chaclas also became the Chief Compliance Officer in June 2018. In his role, he provides legal support for all capital markets, transactional, compliance, commercial, regulatory, governance, intellectual property and other operational activities of the Company worldwide. Mr. Chaclas joined the Company in 2010 as Associate General Counsel and Chief Intellectual Property Counsel, where he managed the Company's global intellectual property portfolio and supported the legal activities of several of the Company's commercial businesses. Prior to joining the Company in 2010, Mr. Chaclas was Deputy General Counsel and Chief Counsel for the software division of Pitney Bowes where he led its Intellectual Property, Technology Law and Procurement legal functions. Mr. Chaclas holds a bachelor's degree in Mechanical Engineering from Tufts University and a Juris Doctorate from Pace University.

Alice L. M. Heezen, Senior Vice President, Human Resources. Ms. Heezen, age 50, became the Company's Senior Vice President, Human Resources in April 2018 after joining the Company in January 2017 as Director of Human Resources for the Europe, Middle East, and Africa region. Prior to joining the Company, she was Head of Human Resources for ADAMA Agricultural Solutions Europe from July 2013 to December 2016. Ms. Heezen has also held senior HR leadership roles at Fiberweb plc, a London listed global specialty industrial and construction materials business from 2010 to 2013, at BG Group, a global oil and gas company from 2005 to 2009, and at REXAM plc, a global consumer packaging company from 2001 to 2005. Ms. Heezen holds a master's degree in Social and Organizational Psychology from University of Leiden, The Netherlands.

Nicolas Joly, Vice President of Plastics & Feedstocks. Mr. Joly, age 43, was named Vice President of Plastics & Feedstocks in May 2020. Mr. Joly began at Trinseo in 2010 and has most recently served as Trinseo's Global Director of Polystyrene & Feedstocks since 2017, after serving as Trinseo's Integrated Business Services Director for Europe, Middle East, and Africa region since 2015. In 2012, Mr. Joly was named Product Manager for Polycarbonate Compounds and Blends, before moving on to become Global Product Director for Polycarbonate in 2013. He previously worked at The Dow Chemical Company in 2002 where he held a series of sales and marketing roles in Plastics. He began his career at Procter & Gamble in 2001. Mr. Joly holds a Master of Science in Chemical Engineering from CPE Lyon.

Andre Lanning, Vice President of Strategy, Corporate Development & Marketing Communication. Mr. Lanning, age 55, was named Vice President of Strategy, Corporate Development & Marketing Communication in May 2020. Previously, Mr. Lanning served as Global Business Director for Trinseo's Synthetic Rubber Business. Mr. Lanning brings thirty years of chemical industry experience to Trinseo, joining the business from Advanced Refining Technologies (ART), where he served as Managing Director/CEO of ART Hydroprocessing; a joint venture between WR Grace and Chevron, based in the United States. Throughout his career, Lanning has held several senior business leadership roles, including in the Pulp & Paper, Fertilizer, and Refining Catalyst sectors. Prior to his current role, Mr. Lanning served as Global Business Director for Trinseo's Synthetic Rubber Business. Mr. Lanning holds a Master of Science in Chemical Engineering from the University of Twente, The Netherlands, and a Master of Business Administration from TSM Business School.

Ryan Leib, Vice President and Treasurer. Mr. Leib, age 43, joined Trinseo in August of 2013 as Assistant Controller and was promoted to Corporate Controller in 2014. In 2017, he was promoted to Vice President, Global Controller, and Principal Accounting Officer and was named Vice President and Treasurer in July 2019. Prior to joining Trinseo, Mr. Leib was a senior manager with PricewaterhouseCoopers LLP and spent two years in their national office providing client companies with technical guidance on complex accounting issues. Mr. Leib holds a bachelor's degree in accounting from St. Joseph's University and is a Certified Public Accountant.

James Ni, Vice President, Latex Binders. Mr. Ni, age 51, was named Vice President, Latex Binders in September 2020 and had previously served as Asia Pacific (APAC) Business Director, Latex Binders since 2017. Mr. Ni remains Managing Director, APAC, a position in which he provides leadership across the region in driving critical priorities and growth projects. Mr. Ni joined Trinseo as Commercial Director of Trinseo Latex in 2010, and was promoted to Business Director, APAC, in 2012. Prior to joining Trinseo, he worked as Sales Director of Emulsion Polymers at Dow Chemical (China) Co., Ltd. since 1995. During his 15-year tenure there, Mr. Ni was promoted several times and acquired extensive knowledge and experience in resin, polymers and latex business both in China and

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OUR COMPANY'S EXECUTIVE OFFICERS

in the US. Mr. Ni holds a Master of Business Administration (MBA) from Central Michigan University, Graduate School of Business, and a Bachelor of Science in Mechanical Engineering from Shanghai Jiao Tong University.

Francesca Reverberi, Vice President, Engineered Materials & Synthetic Rubber. Ms. Reverberi, age 49, was named Vice President, Engineered Materials & Synthetic Rubber in May 2020. Ms. Reverberi has previously served as Global Business Director of Performance Plastics at Trinseo, with responsibility for the Automotive, Consumer Electronics, Medical, Sheet & Extrusion, and Building & Construction plastics markets. Ms. Reverberi's tenure at Trinseo also includes the position of Business Director of Basic Plastics and prior to that, Global Business Director for Synthetic Rubber. Ms. Reverberi joined Trinseo following the Company's carve-out from The Dow Chemical Company in June 2011. During her time at Dow, Ms. Reverberi served as Product Director for Emulsion Polymers, Europe and the Americas, as well as Commercial Manager in Dow Hydrocarbons Aromatics and Derivatives in Europe, including responsibilities for the C4's business and held several positions in other specialty businesses such as Water Solutions and Chelants. Ms. Reverberi holds a Bachelor and Master of Science in Chemical Engineering from Politecnico di Milano and a Master of Business Administration from SDA Bocconi.

Rainer Schewe, Vice President—Supply Chain Services. Schewe, age 57, joined the Company in April 2020 as Vice President—Supply Chain Services. Prior to joining Trinseo, Mr. Schewe served as Executive Vice President and Chief Supply Chain Officer for A. Schulman, Inc. (now LyondellBasell Industries). Prior to this role, he served as Vice President and Business Unit Director for Schulman's Custom Performance Colors business in EMEA. Mr. Schewe holds a degree as a State-Certified Engineer in Chemical Engineering from Fresenius Akademie Wiesbaden in Germany, and an Apprenticeship as a Chemical Laboratory Technician from RWTH Aachen in Germany.

Bernard M. Skeete, Vice President, Chief Accounting Officer and Global Controller. Mr. Skeete, age 47, joined Trinseo in October 2016 as Chief Audit Executive with responsibility for the Company's internal audit and enterprise risk management functions. Previously, Mr. Skeete served as Executive Director of Financial Operations at Comcast Cable from April 2015 to October 2016. Prior to joining Comcast, Mr. Skeete held various positions in corporate audit, controllers and financial planning and analysis with the Campbell Soup Company, with his last position being a Senior Manager of Financial Planning & Analysis for Supply Chain. Mr. Skeete began his career at PricewaterhouseCoopers, where he practiced for over eleven years, most recently as Senior Manager of Assurance & Business Advisory Services. Mr. Skeete holds a bachelor's degree in accounting from St. Joseph's University and is a Certified Public Accountant and Chartered Global Management Accountant.

Timothy J. Thomas, Vice President, Manufacturing and Operations Excellence. Mr. Thomas, age 54, has been with the Company since its inception and has previously held positions of increasing responsibility related to the Company's manufacturing operations, including Global Business Manufacturing Leader—Latex and Operations Director—Performance Materials. In October 2019, Mr. Thomas was named Vice President—Manufacturing and Operational Excellence. Prior to joining Trinseo, Mr. Thomas served in various roles at The Dow Chemical Company, most recently as Business Manufacturing leader for Latex Binders. Mr. Thomas holds a bachelor's degree in Chemical Engineering from Youngstown State University.

Diversity of Executive Officers

Similar to our Board diversity, the Company believes a broad range of backgrounds and personal experience help the Company operate, strategize and solve problems more effectively. We believe our executive officers reflect this diversity of viewpoints and backgrounds. Two of our executive officers are women, two self-identify as a member of an underrepresented minority group, and five are non-U.S. citizens.

GRAPHIC   GRAPHIC   GRAPHIC

Charts do not include our CEO and President, Frank Bozich. Mr. Bozich is reflected in the Board diversity discussion.

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TRANSACTIONS WITH RELATED PERSONS

Transactions with Related Persons

Certain Relationships and Related Transactions

Our Conflict of Interest Policy is designed to help our directors, executive officers, and employees address situations that may involve a conflict of interest, which may include related party transactions. These include situations in which an individual's personal interests are in conflict with the interests of the Company; situations in which an individual or family member receives personal benefits as a result of his or her position with the Company; and situations that may otherwise cast doubt on his or her ability to act objectively with or on behalf of the Company. The Company annually surveys our executive officers and directors regarding potential conflicts of interest. If such conflicts are reported or found, the Legal Department and/or our Chief Compliance Officer will seek to mitigate or eliminate such potential or actual conflicts of interest.

Our audit committee charter requires that the audit committee review and approve all related party transactions. The Company also has a written Related Party Transactions Policy. When related party transactions between us and our officers, directors and principal shareholders and their affiliates, are approved by the audit committee, it does so with the understanding that the terms of such transaction are no less favorable to us than those that we could obtain from unaffiliated third parties.

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STOCK OWNERSHIP INFORMATION

Stock Ownership Information

The following table sets forth information regarding the beneficial ownership of our ordinary shares, nominal value $0.01, as of March 15, 2021 by:

    each person or group of affiliated persons known by us to be the beneficial owner of more than 5% of our ordinary shares;

    each of our named executive officers, directors and director nominees; and

    all of our directors, director nominees and executive officers as a group.

As of March 15, 2021, we had 38,700,293 ordinary shares outstanding (excluding treasury shares), all of which were held by public investors (including certain of our directors and executive officers), the details of which are reflected in the table below.

Information with respect to beneficial ownership has been furnished by each director, director nominee, executive officer or beneficial owner of more than 5% of our ordinary shares. We have determined beneficial ownership in accordance with SEC rules. These rules generally attribute beneficial ownership of shares to persons who possess sole or shared voting or investment power with respect to such shares. The information does not necessarily indicate beneficial ownership for any other purpose. Under these rules, the number of ordinary shares deemed outstanding includes shares issuable upon exercise of options held by the respective person or group which may be exercised within 60 days after March 15, 2021. These shares are deemed to be outstanding and beneficially owned by the person holding those options for the purpose of computing the percentage ownership of that person or entity, but they are not treated as outstanding for the purpose of computing the percentage ownership of any other person or entity.

The inclusion in the following table does not constitute an admission that the named shareholder is a direct or indirect beneficial owner. Unless otherwise indicated and subject to applicable community property laws, to our knowledge, each shareholder named in the following table possesses sole voting and investment power over the shares listed, except for those jointly owned with that person's spouse.

Name




Total
Number of Shares
Beneficially Owned



Percent
of Class (1)




Of Number of Shares Beneficially
Owned, Shares which May be
Acquired within 60 Days (2)
 
M&G Investment Management Limited (3)     7,671,044   19.9%      
BlackRock, Inc. (4)   6,493,523   16.8%    
AllianceBernstein (5)     2,453,863   6.3%      
Frank A. Bozich   104,540   *   77,540  
David Stasse     33,066   *     8,300  
Angelo N. Chaclas   50,726   *   35,272  
Alice L. M. Heezen     18,621   *     16,883  
Andre Lanning   2,014   *   2,014  
Timothy M. Stedman     44,237   *     33,432  
Joseph Alvarado   11,351   *   4,955  
Jeffrey J. Cote     15,787   *     4,955  
Pierre-Marie De Leener   18,075   *   4,955  
Jeanmarie Desmond     0   *      
Matthew Farrell   12,000   *    
K'Lynne Johnson     11,381   *     4,955  
Sandra Beach Lin   4,955   *   4,955  
Philip R. Martens     12,870   *     4,955  
Donald T. Misheff   16,195   *   4,955  
Henri Steinmetz     26,015   *     4,955  
Mark Tomkins   7,755   *   4,955  
Victoria Brifo     0   *      
All Directors, Nominees and Executive Officers as a Group (24 persons) (6)   399,349   1.0%   229,778  
*
Indicates less than one percent.

(1)
The ownership percentages set forth in this column are based on the Company's outstanding ordinary shares (excluding treasury shares) as of March 15, 2021 and assume that each of the beneficial owners continued to own the number of shares reflected in the table on such date.

(2)
Includes options to purchase ordinary shares which have vested or will vest within 60 days of March 15, 2021.

(3)
On February 7, 2020 M&G Investment Management Limited ("M&G") filed a Schedule 13D with the SEC reporting beneficial ownership of 7,839,044 of our ordinary shares, with sole voting power and sole dispositive power over such shares. In a Form 4 filed by M&G dated March 11, 2021, M&G reported beneficial ownership of 7,671,044 shares, which number is used in the table. The address of M&G is Governor's House, Laurence Pountney Hill, London, EC4R OHH.

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STOCK OWNERSHIP INFORMATION

(4)
On January 25, 2021, BlackRock, Inc. filed a Schedule 13G/A with the SEC reporting beneficial ownership of 6,493,523 of our ordinary shares as of December 31, 2020 with sole voting power over 6,319,684 shares and sole dispositive power over 6,493,523 shares. The address of BlackRock, Inc. is 55 East 52nd Street, New York, NY 10055.

(5)
On February 15, 2021, AllianceBernstein L.P. filed a Schedule 13G/A with the SEC reporting beneficial ownership of 2,453,863 of our ordinary shares as of December 31, 2020, with sole voting power over 2,075,040 shares, sole dispositive power over 2,452,899 shares and shared dispositive power over 964 shares. The address of AllianceBernstein L.P. is 1345 Avenue of the Americas, New York NY 10105.

(6)
Includes 44,595 restricted stock units which will vest within 60 days of March 15, 2021, and 185,183 options to purchase ordinary shares which have vested, or will vest, within 60 days of March 15, 2021.

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SECURITIES AUTHORIZED FOR ISSUANCE
UNDER EQUITY COMPENSATION PLANS /
DELINQUENT SECTION 16(A) REPORTS

Securities Authorized for Issuance under Equity Compensation Plans

The following table sets forth certain information as of December 31, 2020 with respect to compensation plans under which ordinary shares of the Company may be issued.

Plan Category







Number of securities
to be issued upon
exercise of
outstanding options,
warrants and rights
(a)











Weighted-average
exercise price of
outstanding options,
warrants and rights
(b)












Number of securities
remaining available
for future issuance
under equity
compensation plans
(excluding securities
reflected in column (a))
(c)
 
Equity compensation plans approved by securityholders     2,052,389  (1)   41.19  (2)   1,918,740  
Equity compensation plans not approved by securityholders        
Total     2,052,389     41.19     1,918,740  
(1)
Includes 496,910 restricted stock units, 155,730 performance award stock units, and 1,399,749 options to purchase shares that have been granted under the approved Trinseo S.A. Amended & Restated 2014 Omnibus Incentive Plan and remain outstanding as of December 31, 2020. The restricted stock units and performance stock units will result in the issuance of shares immediately upon vesting, with the vesting of performance stock units subject to the Company's attainment of pre-established performance goals. The options to purchase shares will result in the issuance of shares upon exercise.

(2)
Represents the weighted-average exercise price of the above-mentioned options to purchase shares only. The Company's performance award stock units and restricted stock units do not have associated exercise prices.

Delinquent Section 16(a) Reports

Section 16(a) of the Securities Exchange Act of 1934, as amended, requires our directors and executive officers, among others, to file with the SEC an initial report of ownership of our stock on a Form 3 and reports of changes in ownership on a Form 4 or a Form 5. Persons subject to Section 16 are required by SEC regulations to furnish us with copies of all Section 16(a) forms that they file. Under SEC rules, certain forms of indirect ownership and ownership of company stock by certain family members are covered by these reporting requirements. When requested, we assist our executive officers and directors in preparing initial ownership reports and reporting ownership changes and will file these reports on their behalf. Based solely on a review of the copies of such forms in our possession, and on written representations from our current directors and executive officers, we believe that all of our executive officers and directors filed the required reports on a timely basis under Section 16(a) during 2020.

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PROPOSAL 8

Proposal 8—Advisory Vote on Named Executive Officer Compensation

The Compensation Discussion and Analysis of this Proxy Statement, which immediately follows this proposal, describes our executive compensation program and the compensation of our named executive officers for fiscal 2020. The Board is asking shareholders to cast a non-binding, advisory vote indicating their approval of that compensation by voting FOR the following resolution:

"RESOLVED, that the shareholders of Trinseo S.A. APPROVE, on an advisory basis, the compensation paid to its named executive officers, as disclosed pursuant to the compensation disclosure rules of the Securities and Exchange Commission, including the Compensation Discussion and Analysis, compensation tables and narrative discussion."

As described in detail in the Compensation Discussion and Analysis, we have a total compensation approach focused on performance-based incentive compensation that seeks to:

    Attract and retain industry-leading talent
    Link compensation actually paid to achievement of our financial, operating and strategic goals;

    Reward individual performance and contribution to our success; and

    Use performance measures, including financial and non-financial goals that align our named executive officers' interests with those of our shareholders.

We believe Trinseo's executive compensation program employs positive governance practices and offer substantial levels of at-risk compensation to meaningfully align shareholder interests with those of our named executive officers.

The Board is asking shareholders to support this proposal, as it does annually. Although the vote we are asking you to cast is non-binding, the compensation committee and the Board value the views of our shareholders as expressed in their votes. The Board and the compensation committee will consider the outcome of the vote when determining future compensation arrangements for our named executive officers.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS A VOTE "FOR"
THE ADVISORY VOTE ON NAMED EXECUTIVE OFFICER COMPENSATION.

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COMPENSATION DISCUSSION & ANALYSIS

Compensation Discussion and Analysis

This compensation discussion and analysis (CD&A) section is intended to provide information about our 2020 compensation objectives and programs for our named executive officers. Our 2020 named executive officers are listed below (together, our "NEOs"), which list includes one former executive, Timothy Stedman.

Name

Position
Frank A. Bozich   President and Chief Executive Officer
David Stasse   Executive Vice President and Chief Financial Officer
Angelo N. Chaclas   Senior Vice President, Chief Legal Officer, Chief Compliance Officer and Corporate Secretary
Alice L. M. Heezen   Senior Vice President, Human Resources
Andre Lanning   Vice President of Strategy, Corporate Development & Marketing Communication
Timothy M. Stedman (1)   Former Senior Vice President, Strategy & Corporate Development
(1)
Effective May 1, 2020, Mr. Stedman was appointed as Special Advisor to the CEO and Executive Leadership, in connection with a reorganization of the Company's management team, and left the Company on August 16, 2020.

This CD&A is divided into the following sections:

    Executive Summary

    Compensation Philosophy and Design

    How We Make Compensation Decisions

    2020 Compensation Structure & Performance

    Other Compensation and Tax Matters

Executive Summary

Business Performance

Our 2020 results reflected the global slowdown in economic growth and uncertainty due to the COVID-19 pandemic. Despite these conditions, we were able to limit costs, generate strong cash flow and achieve strong results while keeping our employees safe. We again returned significant cash to our shareholders via dividends and share repurchases. Highlights for the year ended December 31, 2020:

    Reported net income of $67 million, Adjusted EBITDA of $149 million, and cash from operations of $128 million;

    Paid quarterly dividends totaling approximately $61.8 million, or $1.28 per share.

    Repurchased approximately 800,000 of our ordinary shares in open-market purchases for an aggregate purchase price of $25 million.

    Trading price of our ordinary shares (NYSE:TSE) as of year-end 2020 increased 40% since year-end 2019.

    We announced the proposed acquisition of certain assets from Arkema S.A., at an acquisition price of €1.137 billion (approximately $1.36 billion). We believe this acquisition will be highly synergistic and the first step and a key catalyst in the Company's portfolio transformation.

    Successfully navigated the operational, safety and economic challenges presented by the COVID-19 pandemic, without Company-wide downsizing or furloughs.

    Implemented changes to our executive leadership team in connection with our shift to a global functional structure, elevating four Vice Presidents to our executive leadership team.

For further discussion of our use of non-GAAP measures and a reconciliation to the comparable GAAP measure, see "Item 7—Management's Discussion and Analysis of Financial Condition and Results of Operations—Non-GAAP Performance Measures" in our Annual Report on Form 10-K for the year ended December 31, 2020.

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COMPENSATION DISCUSSION & ANALYSIS

Shareholder Approval of Executive Compensation

In 2020 the compensation of our named executive officers was approved by shareholders with approximately 94% of votes cast in favor. Based on this shareholder support of our executive compensation programs, we and the compensation committee believe our compensation program and practices are well aligned with our shareholders' wishes. Our Board members, investor relations and legal function periodically engage with shareholders regarding the structure of our executive compensation programs and corporate governance and we believe the shareholder support of our say-on-pay proposals since 2019 indicates our practices accurately represent the desires of our shareholders. We consider insights obtained through shareholder engagement and the results of our annual advisory say-on-pay proposal to be critical components to the compensation committee's design and oversight of the Company's executive compensation programs.

During fiscal 2020, the compensation committee of the Board reviewed our executive compensation peer group and concluded our peer group adequately aligned our executive officers' pay opportunities with our compensation philosophy. The compensation committee also approved performance metrics for incentive pay that, consistent with prior years, were designed to correlate with the way we evaluate our operational results and reflect measures of performance that drive returns for our stockholders. We will continue to evaluate opportunities to enhance our compensation programs to attract top talent and provide further alignment with the interests of our shareholders.

Compensation Philosophy and Design

Overview

Our executive compensation policies and programs are designed to attract, retain and motivate key executives through competitive and cost-effective programs that reinforce executive accountability and reward the achievement of business and individual results. Executive compensation consists of four main elements: (1) base salary, (2) annual cash incentive awards, (3) long-term incentive compensation, and (4) retirement savings and benefit programs. The relative weighting of each element is aligned with our philosophy of linking pay to performance. A substantial percentage of our executives' compensation is provided in the form of performance-based variable compensation with a greater emphasis on variable components for our senior executives. Annual cash awards are directly linked to corporate results and short-term performance measures, including financial and non-financial goals. Our equity incentive awards align our executives' interests with those of our shareholders and our long-term business objectives. Executive retirement and benefits programs are generally consistent with the broader employee programs offered in the country where an executive primarily provides services to the Company. We provide limited perquisites to our executives and senior management, and such perquisites are only provided to the extent that they reflect particular business needs and objectives.

We strive to provide our NEOs with a compensation package that is market competitive within our industry and recognizes and rewards superior individual and Company performance.

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COMPENSATION DISCUSSION & ANALYSIS

Compensation Mix

The charts below show the 2020 target mix of compensation between salary and short- and long-term incentive compensation for Mr. Bozich, and for our other NEOs as a group. Long-term incentive compensation remains the largest component of our NEOs' compensation in order to incentivize long-term value creation and to provide continued alignment between the interests of our NEOs and shareholders.

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COMPENSATION DISCUSSION & ANALYSIS

Maintaining Best Practices Regarding Executive Compensation

Our compensation committee intends to compensate our NEOs in a manner that is consistent with the objectives and design principles outlined above. We have adopted the following compensation practices, which are intended to promote strong corporate governance and alignment with shareholder's interests:

Compensation Committee Practices

Clawback and Recoupment Policies   We have the right to claw back incentive-based compensation to the extent it was awarded on the achievement of financial results subject to an accounting restatement that should have resulted in the executive receiving a lower amount of compensation had our financial results been properly reported. The Board can recoup this compensation by requiring the reimbursement of compensation previously paid, cancelling outstanding vested or unvested equity awards, or taking any other action permitted by law.

Our equity award agreements also provide for the reimbursement of all or part of any annual incentive compensation if there is a breach by the executive of his or her award agreement or any non-competition, non-solicitation, confidentiality or similar covenant or agreement with us or an overpayment of incentive compensation due to inaccurate financial data.

Share Ownership Guidelines   The compensation committee has adopted share ownership guidelines equal to (i) six times base salary for the CEO, and (ii) two times base salary for our other NEOs. All executives to whom the share ownership guidelines apply were in compliance at year-end 2020. The guideline must be achieved by 5 years from the date of hire for newly hired executives.

Until the ownership requirement is met, the executive must retain as a holding requirement: (i) 50% of the shares issued after vesting and settlement of restricted stock units ("RSUs") (shares net of all applicable taxes), and (ii) 50% of the shares issued following the exercise of a stock option or the vesting and settlement of performance stock units ("PSUs") (after satisfaction of the exercise price and net of all applicable taxes and full cost to exercise, as applicable).

Mitigate Undue Risk and Risk Assessment   The compensation committee regularly assesses whether our compensation programs and arrangements for our employees encourage excessive risk-taking. We mitigate undue risk in our compensation program by instituting strong governance policies such as capping potential payments, utilizing multiple performance metrics, striking a balance between short- and long-term incentives and adopting share ownership requirements.
Compensation at Risk   We grant a high percentage of at-risk compensation to our executive officers. We believe this is essential to creating a culture of pay-for-performance.
Double-Trigger Change-in-Control Provisions   Our executive officers only receive change-in-control benefits under their equity awards or their employment agreements if their employment is also terminated without cause (or by the executive for good reason) within a specified period following a change in control.
No 280G Gross-Up Provisions   The compensation committee does not permit 280G gross-up provisions in the Company's executive employment agreements and amendments.
Anti-Hedging and Pledging Policy   We prohibit our directors, executive officers, and all employees from hedging or pledging the Company's securities.
Independent Compensation Consultant   The compensation committee retains and annually reviews the independence of its compensation consultant.

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COMPENSATION DISCUSSION & ANALYSIS

How We Make Compensation Decisions

Our compensation & talent development committee (the "compensation committee") is responsible for, among other matters: (1) reviewing key executive compensation goals, policies, plans and programs; (2) reviewing the compensation of our executive officers; (3) reviewing and approving employment agreements and other similar arrangements between the Company and our executive officers; and (4) administering our equity-based plans and other incentive compensation plans.

Our Chief Executive Officer and President reviews annually with the compensation committee each NEO's performance (other than his own) and recommends to the compensation committee appropriate base salary, annual cash incentive awards and long-term equity incentive awards (to the extent applicable with respect to a particular year) for these NEOs. Based upon the recommendations of our Chief Executive Officer and President, and after considering the objectives of our executive compensation program, as described above, as well as the factors described below under "Use of Benchmarking Comparison Data", the compensation committee approved the annual compensation packages of our executive officers. In 2020, the compensation committee also approved Mr. Bozich's compensation, including his base salary, annual cash incentive award, long-term equity incentive awards. See "—Narrative Disclosure to Summary Compensation Table and Grants of Plan Based Awards Table; Other Narrative Disclosure" for a description of each NEO's employment agreement terms.

In making decisions with respect to any element of a NEO's compensation, the compensation committee considered the total compensation that may be awarded to the executive, including salary, annual cash incentive awards and long-term incentive compensation. In addition, in reviewing and approving employment agreements for our NEOs, the compensation committee considered the other benefits to which the officer is entitled by the agreement, including compensation payable upon termination of the executive's employment under a variety of circumstances. Our goal is to award compensation that is competitive to attract and retain highly qualified leaders and that motivates them to drive strong business performance. We believe that our compensation programs align executive and shareholder interests, while allowing compensation to vary based on each executive's individual contributions to the Company and to the Company's overall performance.

Use of Independent Compensation Consultant

The compensation committee has retained Willis Towers Watson as its independent compensation consultant. Willis Towers Watson provides the compensation committee with advice on a broad range of executive compensation matters. The scope of their services includes, but is not limited to, the following:

    Apprising the compensation committee of compensation-related trends and developments in the marketplace;

    Informing the compensation committee of regulatory developments relating to executive compensation practices;

    Providing the compensation committee with an assessment of the market competitiveness of the Company's executive compensation;

    Assessing the composition of the peer companies used for comparative purposes;

    Assessing the executive compensation structure to confirm that no design elements encourage excessive risk taking; and

    Identifying potential changes to the executive compensation program to maintain competitiveness and ensure consistency with business strategies, good governance practices and alignment with shareholder interests.

During fiscal 2020, Willis Towers Watson attended all but one of the regularly scheduled meetings of the compensation committee.

In addition to providing the compensation committee with these executive compensation consulting services in 2020 for which it received aggregate fees of $208,000, Willis Towers Watson also provided the Company with the following additional services for which it received fees totaling $425,000: international actuarial support for pension plans in multiple countries, including global actuarial coordination of results; actuarial support for one of the Company's U.S. welfare benefit plans; health and benefit brokerage services; and rewards data surveys. Before Willis Towers Watson undertook any compensation support work for the Company's management, the compensation committee was consulted and approved the scope of work.

The compensation committee actively considered the range of the additional services that Willis Towers Watson was already providing to the Company when it made the decision to retain Willis Towers Watson as its independent compensation consultant in 2020. The compensation committee assessed the independence of Willis Towers Watson pursuant to applicable SEC rules and concluded that no conflict of interest exists that would prevent Willis Towers Watson from independently representing the compensation committee.

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Use of Benchmarking Comparison Data

The compensation committee selects a peer group of companies, with assistance from Willis Towers Watson, for use in making compensation decisions with respect to the total mix and amount of compensation. This peer group consists of companies in the chemical and chemical-related industries, as well as companies in the container and packaging and the paper and forest product industries. The compensation committee reviewed various market-based metrics of the peer group that it deemed appropriate, which included enterprise value, revenue, market capitalization, and EBITDA margins, to establish compensation benchmarks.

The compensation committee may annually review the companies included in our peer group and may add or eliminate companies as it determines is appropriate. For 2020, the compensation committee maintained the same peer group as the prior year. The peer group selected for making fiscal 2020 compensation decisions consisted of the following 20 companies:

Ashland Global Holdings Inc.   H.B. Fuller Company   Silgan Holdings Inc.
Avient Corporation (1)   Kraton Corporation   Stepan Company
Cabot Corporation   Methanex Corporation   Tronox Limited
Domtar Corporation   Minerals Technologies Inc.   Valvoline Inc.
Element Solutions Inc.   NewMarket Corporation   Venator Materials PLC
Graphic Packaging Holding Company   Olin Corporation   W. R. Grace & Co.
Greif, Inc.   RPM International Inc.  
(1)
Formerly PolyOne Corporation

Additionally, the compensation committee reviewed data from Willis Towers Watson to supplement data from the peer group. This data allowed the compensation committee to obtain a broader understanding of market compensation levels.

2020 Compensation Structure & Performance

The principal components of our executive compensation program include both short-term and long-term compensation. Short-term compensation consists of an executive's annual base salary and annual cash incentive award. Long-term compensation may include grants of share-based incentives as determined by the compensation committee. Certain elements of compensation of our NEOs were determined through direct negotiation with the executives at the time of their hiring.

Base Salary

Setting appropriate levels of base pay allows us to attract and retain an executive leadership team that will continue to meet our commitments to customers, sustain profitable growth and create value for our shareholders. The base salaries for our NEOs are determined based on the scope of their responsibilities and our compensation committee members' collective knowledge of competitive compensation levels, as well as competitive compensation benchmarking data from Willis Towers Watson based on our peer group and survey data. Base salaries are reviewed annually by the compensation committee and adjusted from time to time to reflect individual responsibilities, performance and experience, as well as market compensation levels.

In 2020 the compensation committee approved a 5.7% increase to Mr. Stasse's base salary. There were no increases to base salary approved for Messrs. Bozich or Chaclas, or Ms. Heezen. Under the term of his employment agreement, Mr. Lanning's base salary was CHF 458,191.50 for 2020. Mr. Stedman's base salary was increased to CHF 495,000 before his departure from the Company.

Annual Cash Incentive Plan

Our annual cash incentive plan ("ACI Plan") is designed to create a pay for performance culture by aligning the compensation program to the achievement of our strategic and business objectives and with shareholder interests. Our business objectives are to: (1) provide a safe working environment; (2) deliver strong recurring profits relative to our industry; (3) effectively manage our working capital; (4) demonstrate effective cost management; and (5) provide EBITDA growth that is stronger than the industry. The actual amount that will be paid in respect of an ACI Plan award is based on a combination of the achievement of Company performance goals as well as individual performance. The performance goals and metrics are reviewed and approved by the compensation committee at the beginning of the year. At the end of the year, the amount paid to each NEO is based on the achievement of the Company performance goals and an assessment of the executive's overall performance.

For 2020, the ACI Plan was designed to align our executives' compensation with the Company's business plan and priorities for the year, and reward performance based on the following three components:

    Financial Performance: measured by Company EBITDA, adjusted as described below;

    Responsible Care®: Injuries, Spills and Process Safety Incidents; and

    Individual Goals: Performance against defined business/functional and individual goals.

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We believe that Adjusted EBITDA is a key measure of our financial performance, removing the impacts of our capital structure (such as interest expense), asset base (such as depreciation and amortization) and tax structure as well as other non-recurring items. Therefore, for purposes of the annual cash incentive plan, we define Adjusted EBITDA, which is considered a non-GAAP measure, as net income (loss) from continuing operations before interest expense, net provision for income taxes; depreciation and amortization expense; loss on extinguishment of long-term debt; asset impairment charges; gains or losses on the disposition of businesses and assets, restructuring charges; acquisition related costs and benefits, and other items. Our Adjusted EBITDA performance target metric for the 2020 ACI Plan awards was set consistent to our 2020 business plan that was approved by the Board, but is adjusted to exclude earnings from the Company's American Styrenics segment and its Feedstocks segment, and to exclude the impacts of raw material timing. Despite the impact of the COVID-19 pandemic on the global economy, the Company achieved Adjusted EBITDA in line with its business plan for 2020, as well as successfully bidding to acquire certain assets of Arkema S.A., in a transformational acquisition for the Company. See "Item 7—Management's Discussion and Analysis of Financial Condition and Results of Operations—Non-GAAP Performance Measures" of our Annual Report on Form 10-K for the year ended December 31, 2020 for more information on our approach to calculating Adjusted EBITDA and a reconciliation to the comparable GAAP measure. We exclude the earnings of our Americas Styrenics segment because as a joint venture the Company does not have direct control of its day-to-day operations. Additionally, we also exclude the earnings of our Feedstocks segment and the impacts of raw material timing because market volatility within this segment and timing impacts are generally outside of our executives' control but can have a significant positive or negative impact on the Company's financial performance.

We believe industry-leading environmental, health and safety metrics, as well as individual performance, are important measures for establishing performance objectives and measuring the performance of our NEOs. We are a Responsible Care® company and our environment, health and safety policy states that protecting people and the environment is part of everything we do and every decision we make. Each employee has a responsibility to ensure that our products and operations meet applicable government and Company standards.

The 2020 ACI Plan includes three key environment, health and safety metrics that we track for our Company—Recordable Injuries as defined by OSHA, Process Safety Incidents as defined by the American Chemistry Council, and Loss of Primary Containment, which defines a containment as any physical device used to contain a chemical or plastic resin as part of our manufacturing processes. Incentive payouts with respect to these metrics are determined based on our achievement rating for Responsible Care® performance and in accordance with the threshold, target and maximum levels set forth in the table below.

In addition, each NEO had individual performance goals that included, depending on the NEO: corporate Adjusted EBITDA; asset, product optimization and customer profitability; organizational effectiveness; people; and cost management. The results achieved against each of these individual goals were assessed by the compensation committee and a percentage rating was assigned to each NEO.

The table below shows the weight and targets of the component metrics, along with the payout opportunity for the ACI Plan.

Performance Goal





Weight of
Metric in
ACI Plan (%)





Threshold
Target





100%
Performance
Target




Exceeds
Target
 

1. Financial Performance

                         

2020 Adjusted EBITDA Target (Per 2020 Business Plan)

  60 % $ 219M   $ 258M   $ 323M  

2. Responsible Care®

                         

Recordable Injuries*

  5 % 7   5   3  

Loss of Primary Containment*

    5 %   7     5     3  

Process Safety Incidents*

  5 % 2   1   0  

Responsible Care ® Sub-total

    15 %                  

3. Individual Goals

  25 %      

Total Opportunity at Target

    100 %                  

Maximum Opportunity

  200 %      
*
Metrics represent incident count.

The Company's financial performance metric was based on an Adjusted EBITDA target of $258 million and threshold Adjusted EBITDA target of $219 million. The actual year-end Adjusted EBITDA for purposes of the 2020 ACI Plan was $245 million, which represents the Company's year-end Adjusted EBITDA of $299 million excluding $67 million and $5 million in earnings from our joint ventures and Feedstocks segment, respectively, and excluding the negative impact of $18 million of unfavorable raw material timing, as described above. Based on our 2020 audited financial results, our compensation committee determined that our financial performance component

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resulted in 86% payout of the Adjusted EBITDA component of the ACI Plan, as set forth in the table below. All payout values in this table are shown as a percentage of target.

 

Actual
Result




Payout as % of
Target




Payout as % of
Total Target Bonus


Financial Performance (Adjusted EBITDA)

  $ 245M     86 %   52 %

Our achievement rating for the Responsible Care® portion of the bonus qualified each NEO for 83% of the Responsible Care® component of the ACI Plan, as set forth below. All payout values in this table are shown as a percentage of target.

 

Actual
Result




Payout as % of
Target




Payout as % of
Total Target Bonus


Responsible Care®

                   

Recordable Injuries*

  9   0 % 0 %

Loss of Primary Containment*

    6     50 %   2.5 %

Process Safety Incidents*

  0   200 % 10 %

Responsible Care® Total

          83 %   12.5 %
*
Metrics represent incident count.

The table below shows the contribution of each performance metric under our ACI Plan to the actual bonus award earned by our NEOs. All values in this table are shown as a percentage of target.

NEO


EBITDA
(60%)


Responsible
Care (15%)


Individual
Goals (25%)


Actual Payout
as a % of Target


Frank A. Bozich

86 % 83 % 164 %   105 %  

David Stasse

86 % 83 % 150 % 101 %

Angelo N. Chaclas

86 % 83 % 147 %   101 %  

Alice L. M. Heezen

86 % 83 % 112 % 92 %

Andre Lanning

86 % 83 % 125 %   95 %  

Timothy M. Stedman

86 % 83 % 100 % 89 %

During 2020, the target bonus for each NEO under the ACI Plan was based on a percentage of base salary. The table below shows the 2020 target annual incentive award for each NEO and the actual award payable, based on Company performance metrics and individual performance goals.

NEO


Target Payout
as % of Base Salary


Target Payout
Amount


Actual Payout
as a % of Target


Actual Payout
Amount


Frank A. Bozich

130 % $ 1,300,000   105 %   $ 1,364,354  

David Stasse

70 % $ 350,000 101 % $ 355,110

Angelo N. Chaclas

70 % $ 311,500   101 %   $ 313,712  

Alice L. M. Heezen (1)

55 % $ 223,839 92 % $ 205,843

Andre Lanning (1)

28 % $ 137,402   95 %   $ 130,822  

Timothy M. Stedman (1) (2)

65 % $ 309,251  (2) 89 %