UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 6)¹

Infinity Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, $0.001 par value

(Title of Class of Securities)

45665G303

(CUSIP Number)

JAMES KRATKY

BVF Partners L.P.

44 Montgomery St., 40th Floor

San Francisco, California 94104

(415) 525-8890

ADAM W. FINERMAN, ESQ.

OLSHAN FROME WOLOSKY LLP

1325 Avenue of the Americas

New York, New York 10019

(212) 451-2300

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

February 11, 2021

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ☒.

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See § 240.13d-7 for other parties to whom copies are to be sent.

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

The following constitutes Amendment No. 6 to the Schedule 13D filed by the undersigned (“Amendment No. 6”). This Amendment No. 6 amends the Schedule 13D as specifically set forth herein.

Items 5(a) – (c) are hereby amended and restated to read as follows:

(a)       The aggregate percentage of Shares reported owned by each person named herein is based on 64,206,758 Shares outstanding as of November 3, 2020, as disclosed in the Issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on November 9, 2020.

As of the close of business on February 16, 2021 (i) BVF beneficially owned 4,448,421 Shares, representing percentage ownership of approximately 6.9% of the Shares outstanding, (ii) BVF2 beneficially owned 3,279,831 Shares, representing percentage ownership of approximately 5.1% of the Shares outstanding, (iii) Trading Fund OS beneficially owned 534,847 Shares, representing percentage ownership of less than 1% of the Shares outstanding and (iv) 120,546 Shares were held in the Partners Managed Account, representing percentage ownership of less than 1% of the Shares outstanding.

BVF GP, as the general partner of BVF, may be deemed to beneficially own the 4,448,421 Shares beneficially owned by BVF, representing percentage ownership of approximately 6.9% of the Shares outstanding.

BVF2 GP, as the general partner of BVF2, may be deemed to beneficially own the 3,279,831 Shares beneficially owned by BVF2, representing percentage ownership of approximately 5.1% of the Shares outstanding.

Partners OS, as the general partner of Trading Fund OS, may be deemed to beneficially own the 534,847 Shares beneficially owned by Trading Fund OS, representing percentage ownership of less than 1% of the Shares outstanding.

BVF GPH, as the sole member of each of BVF GP and BVF2 GP, may be deemed to beneficially own the 7,728,252 Shares beneficially owned in the aggregate by BVF and BVF2, representing percentage ownership of approximately 12.0% of the Shares outstanding.

Partners, as the general partner of BVF and BVF2, the sole member of Partners OS, and the investment manager of Trading Fund OS and the Partners Managed Account, may be deemed to beneficially own the 8,383,645 Shares beneficially owned in the aggregate by BVF, BVF2, Trading Fund OS, and the Partners Managed Account, representing percentage ownership of approximately 13.1% of the Shares outstanding.

BVF Inc., as the general partner of Partners, may be deemed to beneficially own the 8,383,645 Shares beneficially owned by Partners, representing percentage ownership of approximately 13.1% of the Shares outstanding.

Mr. Lampert, as a director and officer of BVF Inc. may be deemed to beneficially own the 8,383,645 Shares beneficially owned by BVF Inc., representing percentage ownership of approximately 13.1% of the Shares outstanding.

(b)       Each of BVF, BVF2, and Trading Fund OS, shares with Partners voting and dispositive power over the Shares each such entity beneficially owns. BVF shares with BVF GP voting and dispositive power over the Shares beneficially owned by BVF. BVF2 shares with BVF2 GP voting and dispositive power over the Shares beneficially owned by BVF2. Each of BVF GP and BVF2 GP shares with BVF GPH voting and dispositive power over the Shares each such entity beneficially owns. Trading Fund OS, shares with Partners OS, voting and dispositive power over the Shares beneficially owned by Trading Fund OS. Partners, BVF Inc. and Mr. Lampert share voting and dispositive power over the 8,383,645 Shares they may be deemed to beneficially own with BVF, BVF GP, BVF2, BVF2 GP, Trading Fund OS, Partners OS, BVF GPH and the Partners Managed Accounts.

(c)       Schedule A annexed hereto lists all transactions in securities of the Issuer by the Reporting Persons since the filing of Amendment No. 5 to the Schedule 13D. All of such transactions were effected in the open market.

The filing of this Schedule 13D shall not be deemed an admission that the Reporting Persons are, for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, the beneficial owners of any securities of the Issuer that he or it does not directly own. Each of the Reporting Persons specifically disclaims beneficial ownership of the securities reported herein that he or it does not directly own.

SIGNATURES

After reasonable inquiry and to the best of his or its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated: February 16, 2021

Schedule A

Transactions in the Shares Since the Filing of Amendment No. 4 to the Schedule 13

BIOTECHNOLOGY VALUE FUND, L.P.

BIOTECHNOLOGY VALUE FUND II, L.P.

BIOTECHNOLOGY VALUE TRADING FUND OS LP

BVF PARTNERS L.P. (THROUGH THE PARTNERS MANAGED ACCOUNTS)