FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person *   Horgen Jay C. 2. Date of Event Requiring Statement (Month/Day/Year) 04/22/2008 3. Issuer Name and Ticker or Trading Symbol AFFILIATED MANAGERS GROUP INC [AMG] (Last) (First) (Middle) C/O AFFILIATED MANAGERS GROUP, INC., 600 HALE STREET 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Executive Vice President 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) PRIDES CROSSING, MA 01965 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5) Common Stock 5,216 (1) D Â

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (Right to Buy)	03/05/2010(2)	03/05/2014	Common Stock	60,000	$ 105.44	D	Â
Employee Stock Option (Right to Buy)	12/31/2012(3)	12/20/2014	Common Stock	93,318	$ 116.35	D	Â

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Horgen Jay C. C/O AFFILIATED MANAGERS GROUP, INC. 600 HALE STREET PRIDES CROSSING, MA 01965	Â	Â	  Executive Vice President	Â

Signatures

/s/ John Kingston, III, Attorney-in-Fact		04/23/2008
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(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).
(1)	Mr. Horgen was granted a discretionary award under the Company's Deferred Compensation Plan, which award is invested at the election of Mr. Horgen in common stock of the Company, distributable in 25% increments in each of the years 2009, 2010, 2011 and 2012.
(2)	This option is exercisable over three years, with 33.3% exercisable beginning on each of March 5, 2008, 2009 and 2010. The exercisability of the option would be accelerated upon a change of control of the Company.
(3)	This option is exerciable over five years, with 22.5% exercisable beginning on each of December 31, 2008, 2009, 2010 and 2011 and 10% exercisable on December 31, 2012. The exercisability of the option would be accelerated upon a change of control of the Company.

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