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) February 1, 2011

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):

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

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

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

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

ITEM 2.02             Results of Operations and Financial Conditions.

On February 1, 2011, Affiliated Managers Group, Inc. (the “Company”) issued a press release setting forth its financial and operating results for the quarter and year ended December 31, 2010.  A copy of this press release is furnished as Exhibit 99.1 hereto and is hereby incorporated by reference herein.

ITEM 5.02             Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

On February 1, 2011, the Company announced the appointment of three senior executives to the following roles, to be effective as of the Company’s Annual Meeting on May 24, 2011.

Nathaniel Dalton was appointed President of the Company, in addition to continuing to serve as its Chief Operating Officer.

Jay C. Horgen was appointed Chief Financial Officer and Treasurer of the Company, in addition to continuing to oversee the Company’s New Investments activities.

John Kingston, III was appointed Vice Chairman, in addition to continuing to serve as General Counsel of the Company.

Each of Messrs. Dalton, Horgen and Kingston will continue to report to Sean M. Healey, the Chairman and Chief Executive Officer of the Company.

Darrell W. Crate, currently the Company’s Chief Financial Officer, Executive Vice President and Treasurer, will retire from these positions, effective as of the Annual Meeting.

Following the Annual Meeting, Mr. Crate has agreed to provide advisory services on an on-going basis to the Company, through February, 2016. Under the terms of the agreement, Mr. Crate will be eligible to receive compensation in 2011 for his service to the Company in line with his past compensation, ratable for the period of service, all to be determined by the Board of Directors in its compensation determinations at the end of 2011.  Mr. Crate will continue to receive medical and dental insurance for a period of two years, and his Company equity awards will continue to remain outstanding, subject to certain sale restrictions.  As part of his advisory relationship to the Company, Mr. Crate will observe confidentiality and non-competition covenants following his resignation.

The information about Messrs. Dalton and Horgen required under Item 401(b), (d) and (e) of Regulation S-K is incorporated by reference from the Company’s proxy statement on Schedule 14A as filed on April 29, 2010. The Company announced these appointments in a press release on February 1, 2011, a copy of which is furnished as Exhibit 99.2 hereto and is hereby incorporated by reference herein.

ITEM 8.01             Other Events.

The financial statement tables set forth in the press release issued by the Company on February 1, 2011 are also filed as Exhibit 99.3 hereto and are hereby incorporated by reference herein.

ITEM 9.01             Financial Statements and Exhibits.

(c)           Exhibits.

*  This exhibit shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liability of that section, nor shall it be incorporated by reference into any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934.

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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

* This exhibit shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liability of that section, nor shall it be incorporated by reference into any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934.

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Exhibit 99.1

AMG Reports Financial and Operating Results

for the Fourth Quarter and Full Year 2010

Company Reports Economic EPS of $2.02; EPS of $1.18 for Fourth Quarter,

Economic EPS of $6.09, EPS of $2.81 for Full Year 2010

BOSTON, February 1, 2011 – Affiliated Managers Group, Inc. (NYSE: AMG) today reported its financial and operating results for the fourth quarter and full year 2010.

For the fourth quarter of 2010, Economic Earnings Per Share (“Economic EPS”) were $2.02, compared to $1.36 for the same period of 2009, while diluted earnings per share for the fourth quarter of 2010 were $1.18, compared to $0.55 for the same period of 2009.  For the fourth quarter of 2010, Economic Net Income was $106.6 million, compared to $60.0 million for the same period of 2009.  For the fourth quarter of 2010, Net Income was $62.0 million, compared to $24.6 million for the same period of 2009.  (Performance measures Economic Net Income and Economic EPS are defined in the attached tables.)

For the fourth quarter of 2010, revenue was $420.8 million, compared to $244.7 million for the same period of 2009.   For the fourth quarter of 2010, EBITDA was $152.1 million, compared to $79.9 million for the same period of 2009.

For the year ended December 31, 2010, Economic Net Income was $299.1 million, while EBITDA was $404.4 million. For the same period, Net Income was $138.6 million, on revenue of $1.4 billion. For the year ended December 31, 2009, Economic Net Income was $185.7 million, while EBITDA was $242.8 million. For the same period, Net Income was $59.5 million, on revenue of $841.8 million.

Net client cash flows for the fourth quarter of 2010 were approximately $4.7 billion, with flows in the institutional, mutual fund, and high net worth channels of approximately $3.2 billion, $0.8 billion, and $0.6 billion, respectively.  The aggregate assets under management of AMG’s affiliated investment management firms were approximately $320 billion at December 31, 2010.

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“AMG’s fourth quarter was an outstanding finish to an exceptional year,” stated Sean M. Healey, Chairman and Chief Executive Officer of AMG. “Our Economic Earnings Per Share for the fourth quarter were $2.02, an increase of 49% over the same period of 2009, and our assets under management grew 54% over the same period, reflecting the strong investment performance and organic growth of our extant Affiliates as well as investments in four new Affiliates in 2010. We made strong progress across all areas of our global growth strategy during the year, and given our industry-leading offerings in highly attractive product areas, we remain confident in our prospects for continued new business momentum going forward.”

“Our Affiliates produced excellent investment performance in the quarter and the year, particularly in global equity and alternative products, which generate over 70% of our EBITDA. Highlights included Harding Loevner’s global and international products as well as global equity strategies from Tweedy, Browne, which was nominated for International-Stock Manager of the Year by Morningstar.  In addition, the emerging markets strategies from Genesis, Trilogy, and Harding Loevner generated significant outperformance for the year. Finally, a number of our alternative firms contributed material performance fees in 2010, including ValueAct, AQR and BlueMountain, and, together with Pantheon, our alternative managers are well positioned to continue to make a meaningful contribution to our earnings in 2011.”

“Our net client cash flows of $4.7 billion in the fourth quarter capped a strong year of organic growth for our Affiliates, against an industry backdrop of improving, but still muted, investor risk appetite,” Mr. Healey added. “As institutional and retail investors continue to reallocate to risk assets, we see increasing opportunities to win new business globally. Clients outside the U.S., which already contribute over half of our EBITDA, are particularly attracted to our Affiliates’ industry-leading global and emerging markets equity and alternative strategies – and our global distribution effort brings the outstanding products of our return-oriented specialist firms to large institutional clients in Australia, the Middle East, Europe, and Asia. Our platform continues to gain momentum across each of these markets, as sophisticated investors around the world increasingly demand spe cialized alpha-generating strategies.”

Mr. Healey concluded, “We were very pleased with the successful execution of our new investments strategy in 2010, including our investments in Pantheon, Artemis, and Trilogy, which further increased our exposure to outstanding international and emerging markets equity and alternative products. Looking ahead, with our strong competitive position in a favorable transaction environment, and diverse pipeline of prospective Affiliates, we continue to have a substantial opportunity to materially add to our earnings growth through accretive investments in new Affiliates worldwide.”

About Affiliated Managers Group

AMG is a global asset management company with equity investments in leading boutique investment management firms.  AMG’s innovative partnership approach allows each Affiliate’s management team to own significant equity in their firm while maintaining operational autonomy.  AMG’s strategy is to generate growth through the internal growth of existing Affiliates, as well as through investments in new Affiliates.  In addition, AMG provides centralized assistance to its

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Affiliates in strategic matters, marketing, distribution, product development and operations.  As of December 31, 2010, the aggregate assets under management of AMG’s Affiliates were approximately $320 billion, in more than 350 investment products across a broad range of investment styles, asset classes and distribution channels.  For more information, please visit the Company’s website at www.amg.com.

Certain matters discussed in this press release may constitute forward-looking statements within the meaning of the federal securities laws.  Actual results and the timing of certain events could differ materially from those projected in or contemplated by the forward-looking statements due to a number of factors, including changes in the securities or financial markets or in general economic conditions, the availability of equity and debt financing, competition for acquisitions of interests in investment management firms, the ability to close pending investments, the investment performance of our Affiliates and their ability to effectively market their investment strategies, and other risks detailed from time to time in AMG’s filings with the Securities and Exchange Commission.  Reference is hereby made to the “Cautionary Statements” set forth in the Company’s Form 10-K for the year ended December 31, 2009.

AMG routinely posts information that may be significant for investors in the Investor Information section of its website, and encourages investors to consult that section regularly.  For additional information, please visit www.amg.com.

Financial Tables Follow

A teleconference will be held with AMG’s management at 11:00 a.m. Eastern time today.  Parties interested in listening to the teleconference should dial 1-877-407-9210 (domestic calls) or 1-201-689-8049 (international calls) starting at 10:45 a.m. Eastern time.  Those wishing to listen to the teleconference should dial the appropriate number at least ten minutes before the call begins.

The teleconference will also be available for replay beginning approximately one hour after the conclusion of the call.  To hear a replay of the call, please dial 1-877-660-6853 (domestic calls) or 1-201-612-7415 (international calls) and provide account number 286 and conference ID 364882.  The live call and replay of the session, and additional financial information referenced during the teleconference, can also be accessed via the Web at http://www.amg.com/InvestorRelations.

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Affiliated Managers Group, Inc.

Financial Highlights

(dollars in thousands, except per share data)

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Affiliated Managers Group, Inc.

Financial Highlights

(dollars in thousands, except per share data)

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Affiliated Managers Group, Inc.

Reconciliations of Earnings Per Share Calculation

(dollars in thousands, except per share data)

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Affiliated Managers Group, Inc.

Reconciliations of Average Shares Outstanding

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Affiliated Managers Group, Inc.

Operating Results

(in millions)

Assets Under Management

Statement of Changes - Quarter to Date

Statement of Changes - Year to Date

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Affiliated Managers Group, Inc.

Operating Results

(in thousands)

Financial Results

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Affiliated Managers Group, Inc.

Reconciliations of Performance and Liquidity Measures

(in thousands)

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Affiliated Managers Group, Inc.

Consolidated Statements of Income

(dollars in thousands, except per share data)

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Affiliated Managers Group, Inc.

Consolidated Balance Sheets

(in thousands)

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Affiliated Managers Group, Inc.

Consolidated Statements of Cash Flow

(in thousands)