SEI Investments (SEIC) 13F-HR Quarterly holdings report by institutional manager

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: 06-30-2021

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. Peterson		Oaks, PA	08-06-2021
[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).)
X	13F 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 Number	Name
	028-05990	Acadian Asset Management LLC
	028-10562	AllianceBernstein L.P.
	028-10120	AQR Capital Management, LLC
	028-17137	Arcus
	028-13791	ArrowMark Partners
	028-05615	Axiom International Investors LLC
	028-02951	Beutel, Goodman & Company Ltd.
	028-12820	Brigade Capital Management, LP
	028-11728	Causeway Capital Management LLC
	028-11563	Coho Partners, Ltd.
	028-14668	Copeland Capital Management, LLC
	028-14036	Fiera Capital Corporation
	028-14036	Fiera Capital Inc.
	028-18845	Fondsmaeglerselskabet Maj Invest A/S
	028-05229	Great Lakes Advisors, LLC
	028-11957	Hillsdale Investment Management Inc.
	028-04211	INTECH Investment Management LLC
	028-14777	JO Hambro Capital Management Limited
	028-17689	Kettle Hill Capital Management, LLC
	028-13608	LMCG Investments, LLC
	028-06580	LSV Asset Management
	028-13124	Macquarie Investment Management
	028-03673	Manulife Investment Management
	028-03673	Manulife Investment Management Limited
	028-17488	Maple-Brown Abbott Limited
	028-13243	Mar Vista Investment Partners, LLC
	028-03743	Marathon Asset Management, L.P.
	028-04632	Martingale Asset Management, L.P.
	028-13573	Neuberger Berman LLC
	028-17435	NN Investment Partners
	028-12690	Pacific Investment Management Company LLC
	028-03042	PanAgora Asset Management Inc.
	028-04558	Parametric Portfolio Associates LLC
	028-12690	PIMCO
	028-12690	PIMCO Europe Ltd
	028-13350	Poplar Forest Capital, LLC
	028-01549	Principal Global Investors
	028-14009	QS Investors, LLC
	028-19339	Qtron Investments, LLC
	028-11173	Quantitative Management Associates LLC
	028-10674	Ramius Advisors, LLC
	028-14481	RWC Asset Advisors
	028-04691	Schafer Cullen Capital Management, Inc.
	028-00733	SSGA Funds Management, Inc.
	028-00733	State Street Global Advisors Trust Co.
	028-07104	WCM Investment Management
	028-06354	Victory Capital Management Inc.
	028-04413	Wells Capital Management Inc.

Form 13F Summary Page
	Report Summary:
	Number of Other Included Managers:	4
	Form 13F Information Table Entry Total:	4,567
	Form 13F Information Table Value Total:	45,098,785
		(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 Number	Name
	1		EAM Investors LLC
	3	028-16475	SEI Investments Management Corporation
	4	028-10297	SEI Trust Company
	5	028-16449	SEI Investments Canada Company