AFFILIATED MANAGERS GROUP, INC. — Director's Dealing 2010

May 5, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AFFILIATED MANAGERS GROUP INC (AMG)
CIK: 0001004434
Period of Report: 2010-05-03

Reporting Person: DALTON NATHANIEL (Executive V.P. and COO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-05-03	Common Stock	M	18000	$31.96	Acquired	59762	Direct
2010-05-03	Common Stock	M	62754	$44.35	Acquired	59762	Direct
2010-05-03	Common Stock	S	78500	$85.04	Disposed	59762	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-05-03	Employee Stock Option (Right to Buy)	$31.96	M	18000	Disposed	2010-12-19	Common Stock (18000)	Direct
2010-05-03	Employee Stock Option (Right to Buy)	$44.35	M	62754	Disposed	2010-12-10	Common Stock (62754)	Direct

Footnotes

F1: The reported amount is the weighted average sales price of the shares sold; the individual transaction prices ranged from $84.60 to $85.55. Specific transaction details will be provided to the SEC upon request.