The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F COVER PAGE

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Report for the Calendar Year or Quarter Ended:12-31-2020
Check here if Amendment  Amendment Number:
This Amendment (Check only one.):  is a restatement.
  adds new holdings entries.
Institutional Investment Manager Filing this Report:
Name:SEI INVESTMENTS CO
Address:1 FREEDOM VALLEY DRIVE
OAKS, PA  19456-1100
Form 13F File Number:028-16454

The institutional investment manager filing this report and the person by whom it is signed hereby represent that the person signing the report is authorized to submit it, that all information contained herein is true, correct and complete, and that it is understood that all required items, statements, schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:
Name:Michael N. Peterson
Title:Executive Vice President
Phone:610-676-1000
Signature, Place, and Date of Signing:
Michael N. PetersonOaksPA02-08-2021
[Signature][City, State][Date]
SEI Investments Company (SEI) is the parent holding company of certain institutional investment managers, as defined by Section 13(f) of the Securities Exchange Act of 1934, as amended (the "Act"). For purposes of the reporting requirements under Section 13(f) of the Act, and the rules promulgated thereunder, SEI does not exercise, and therefore disclaims, investment discretion with respect to any Section 13(f) securities positions over which its investment operating subsidiaries exercise such discretion. To the extent, however, that SEI's ownership interest in such subsidiaries may nevertheless give rise to a Form 13F obligation for SEI, the information required by Form 13F is reported herein on behalf of the following subsidiaries: SEI Investments Management Corporation ("SIMC"), SEI Trust Company and SEI Investments Canada Company (SEI Canada). Voting authority with respect to the Section 13(f) securities reported herein resides with and is exercised by SEI's operating subsidiaries, unless otherwise indicated. Although SEI has not been delegated voting authority over such Section 13(f) securities, and disclaims such voting authority, pursuant to instruction 12b.viii of Form 13F, and for that purpose only, such Section 13(f) securities are reported as "Sole Voting Authority." SIMC and SEI Canada each serve as an investment adviser to a number of pooled investment vehicles, which may include mutual funds, hedge funds, private equity funds, collective investment trusts and offshore investment funds (together, the "Pooled Investment Vehicles"). In addition, SIMC sponsor and may serve as adviser to, separately managed account programs (SMA Programs) . SIMC and SEI Canada may act as a "manager of managers" whereby each retain, subject to SIMC's and SEI Canada's oversight, respectively, sub-advisers to buy and sell securities on behalf of such Pooled Investment Vehicles and SMA Programs. To the extent that SIMC's and SEI Canada's role as a manager of managers could give rise to a Form 13F obligation, SIMC or SEI Canada has instructed its sub-advisers to file a Form 13F with respect to such securities and has included such sub-advisers in the "list of other managers reporting for this manager" below.
Report Type (Check only one.):
  13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager are reported in this report.)
  13F NOTICE. (Check here if no holdings reported are in this report, and all holdings are reported by other reporting manager(s).)
X13F COMBINATION REPORT. (Check here if a portion of the holdings for this reporting manager are reported in this report and a portion are reported by other reporting manager(s).)
List of Other Managers Reporting for this Manager:
[If there are no entries in this list, omit this section.]
Form 13F File NumberName
028-05990Acadian Asset Management LLC
028-05508AJO, L.P.
028-10562AllianceBernstein L.P.
028-04895Analytic Investors, LLC
028-10120AQR Capital Management, LLC
028-17137Arcus
028-13791ArrowMark Partners
028-05615Axiom International Investors LLC
028-02951Beutel, Goodman & Company Ltd.
028-18913Blackcrane Capital, LLC
028-12820Brigade Capital Management, LP
028-04549Cardinal Capital Management, L.L.C.
028-11728Causeway Capital Management LLC
028-18741CenterSquare Investment Management LLC
028-11563Coho Partners, Ltd.
028-14668Copeland Capital Management, LLC
028-10492Falcon Point Capital, LLC
028-14036Fiera Capital Corporation
028-14036Fiera Capital Inc.
028-18845Fondsmaeglerselskabet Maj Invest A/S
028-05229Great Lakes Advisors, LLC
028-11957Hillsdale Investment Management Inc.
028-04211INTECH Investment Management LLC
028-11937Jennison Associates LLC
028-14777JO Hambro Capital Management Limited
028-20366Jackson Creek Investment Advisory, LLC
028-13513KBI Global Investors
028-17689Kettle Hill Capital Management, LLC
028-13608LMCG Investments, LLC
028-06580LSV Asset Management
028-13124Macquarie Investment Management
028-03673Manulife Investment Management
028-03673Manulife Investment Management Limited
028-17488Maple-Brown Abbott Limited
028-13243Mar Vista Investment Partners, LLC
028-03743Marathon Asset Management, L.P.
028-04632Martingale Asset Management, L.P.
028-13573Neuberger Berman LLC
028-16538Ninety One
028-17435NN Investment Partners
028-01474NWQ Investment Management Company, LLC
028-12690Pacific Investment Management Company LLC
028-03042PanAgora Asset Management Inc.
028-04558Parametric Portfolio Associates LLC
028-12690PIMCO
028-12690PIMCO Europe Ltd
028-13350Poplar Forest Capital, LLC
028-01549Principal Global Investors
028-14009QS Investors, LLC
028-19339Qtron Investments, LLC
028-11173Quantitative Management Associates LLC
028-10674Ramius Advisors, LLC
028-14481RWC Asset Advisors
028-04691Schafer Cullen Capital Management, Inc.
028-00733SSGA Funds Management, Inc.
028-00733State Street Global Advisors Trust Co.
028-07104WCM Investment Management
Form 13F Summary Page
Report Summary:
Number of Other Included Managers:4
Form 13F Information Table Entry Total:4,396
Form 13F Information Table Value Total:38,680,319
(thousands)
List of Other Included Managers:
Provide a numbered list of the name(s) and Form 13F file number(s) of all institutional investment managers with respect to which this report is filed, other than the manager filing this report.
[If there are no entries in this list, state “NONE” and omit the column headings and list entries.]
No.Form 13F File NumberName
1 EAM Investors LLC
3028-16475SEI Investments Management Corporation
4028-10297SEI Trust Company
5028-16449SEI Investments Canada Company