SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* WEST ALFRED P JR (Last) (First) (Middle) ONE FREEDOM VALLEY DRIVE (Street) OAKS PA 19456 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol SEI INVESTMENTS CO [ SEIC ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 06/12/2009
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	06/12/2009		S		3,680	D	$18.24	478,716	I	Held by the 1980 Minority Trust - Alfred P. West III(1)
Common Stock	06/12/2009		S		5,600	D	$18.25	473,116	I	Held by the 1980 Minority Trust - Alfred P. West III(1)
Common Stock	06/12/2009		S		1,400	D	$18.26	471,716	I	Held by the 1980 Minority Trust - Alfred P. West III(1)
Common Stock	06/12/2009		S		300	D	$18.27	471,416	I	Held by the 1980 Minority Trust - Alfred P. West III
Common Stock								16,500,808	D
Common Stock								48,000	I	Held by Wife
Common Stock								9,075,000	I	Held by AP West Associates(2)
Common Stock								64,400	I	Held by Wesst Senior Securities Fund, L.P.(3)
Common Stock								4,376	I	Held by the Residuary Trust(4)
Common Stock								64,394	I	Held by the Marital Trust (GST Exempt)(5)
Common Stock								64,754	I	Held by the Marital Trust (Non-GST Exempt)(5)
Common Stock								2,796,000	I	Held by Life Trust - Alfred P. West III(1)
Common Stock								2,810,590	I	Held by the 1980 Life Trust - Andrew Palmer West(1)
Common Stock								2,801,470	I	Held by the 1980 Life Trust - Angela Paige West(1)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. These shares are held in trusts for the benefit of Mr. West's children. Mr. West's wife is the trustee or a co-trustee of these trust. Mr. West disclaims beneficial ownership of the shares held in these trusts.

2. Mr. West disclaims beneficial ownership of the shares held by APWest Associates, L.P., except to the extent of his pecuniary interest therein.

3. West Senior Securities Fund, L.P. is a limited partnership in which the Residuary Trust, of which Mr. West is trustee, holds a 1% general partnership interest and a 9.5% limited partnership interest. Mr. West disclaims beneficial owernship of the shares held by West Senior Securities Fund, L.P., except to the extent of his pecuniary interest therein.

4. The trust that holds these shares (the "Residuary Trust") is for the benefit of Mr. West's mother and certain descendants of Mr. West's father. The Residuary Trust was created upon the death of Mr. West's father under the terms of an existing trust that Mr. West's father had established prior to his death. In connection with the establishment of the Residuary Trust, Mr. West became the trustee of the Residuary Trust in September 2002. Mr. West disclaims beneficial ownership of the shares held by the Residuary Trust, except to the extent of his pecuniary interest therein.

5. Mr. West is the trustee of the Marital Trusts (GST and non-GSTexempt), which holds shares for the benefit of Mr. West's mother.

Remarks:

	Ruth Montgomery (Attorney in Fact0	06/16/2009
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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