UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT PURSUANT
TO SECTION 13 OR 15(D) OF THE
SECURITIES EXCHANGE ACT OF 1934

Date of report (Date of earliest event reported)    October 11, 2007

Affiliated Managers Group, Inc.

(Exact Name of Registrant as Specified in Its Charter)

Delaware

(State or Other Jurisdiction of Incorporation)

(617) 747-3300

(Registrant’s Telephone Number, Including Area Code)

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

£                                    Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

£                                    Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

£                                    Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

£                                    Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 8.01   Other Events

On October 11, 2007, Affiliated Managers Group, Inc. (the “Company”) announced that it had entered into an agreement to sell convertible trust preferred securities in a private placement to certain qualified institutional investors in an offering exempt from the registration requirements of the Securities Act of 1933, as amended (the “Securities Act”). Pursuant to and in accordance with Rule 135c of the Securities Act, the Company is filing with this Current Report on Form 8-K the press release attached hereto as Exhibit 99.1.  The securities have not been registered under the Securities Act and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements of the Securities Act.

On October 11, 2007, the Company also announced its intent to call all of the $300 million aggregate principal amount of its outstanding floating rate senior convertible securities due 2033 in February 2008. Under the terms of the convertible securities, at the time of the call, holders may elect to convert their debentures into shares of the Company’s common stock. A copy of the related press release is attached to this report as Exhibit 99.2.

ITEM 9.01   Financial Statements and Exhibits

(d)                                 Exhibits.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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EXHIBIT INDEX

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Exhibit 99.1

Contact:  Brett S. Perryman
Laura O’Brien
Affiliated Managers Group, Inc.
(617) 747-3300
ir@amg.com

AMG Announces Sale of $500 Million of Convertible Securities
and Share Repurchase

BOSTON, October 11, 2007 — Affiliated Managers Group, Inc. (NYSE: AMG) announced that it has entered into an agreement to sell $500 million of convertible trust preferred securities due 2037.  The securities carry a coupon of 5.15% per annum and a conversion price of $200, which is a premium of approximately 53% over AMG’s closing stock price of $130.77 on October 11, 2007.

AMG will use a portion of the net proceeds from this offering to repurchase up to 2.0 million shares of its common stock, and expects to use the remainder for general corporate purposes.

The offering will be made only to qualified institutional buyers pursuant to Rule 144A of the Securities Act of 1933, as amended (the “Securities Act”).  The securities will not be registered under the Securities Act, and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements of the Securities Act.  This press release, which is being issued pursuant to and in accordance with Rule 135c of the Securities Act, shall not constitute an offer to sell or the solicitation of an offer to buy the convertible trust preferred securities.

AMG is an asset management company that acquires and holds majority equity investments in a diverse group of boutique investment management firms.  AMG’s affiliated investment management firms managed approximately $267 billion in assets as of June 30, 2007.

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For more information on Affiliated Managers Group, Inc.,
please visit AMG’s Web site at www.amg.com.

Exhibit 99.2

Contact: Brett S. Perryman
Laura O’Brien
Affiliated Managers Group, Inc.
(617) 747-3300
pr@amg.com

AMG ANNOUNCES INTENT TO CALL $300 MILLION
OF FLOATING RATE CONVERTIBLE SECURITIES

BOSTON, October 11, 2007 — Affiliated Managers Group, Inc. (NYSE: AMG) today announced its intent to call all of the $300 million aggregate principal amount of its outstanding floating rate senior convertible securities due 2033 (“convertible securities” or “COBRAs”) in February 2008.

Under the terms of the convertible securities, at the time of the call, holders may elect to convert their debentures into shares of AMG common stock.  Based on the trading price of the Company’s common stock, AMG expects that the substantial portion of the debentures will be converted into common stock.

AMG is an asset management company that acquires and holds majority equity investments in a diverse group of boutique investment management firms.  AMG’s affiliated investment management firms managed approximately $267 billion in assets as of June 30, 2007.

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For more information on Affiliated Managers Group, Inc.,
please visit AMG’s Web site at www.amg.com.