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) January 30, 2008

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))

On January 30, 2008, 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, 2007. A copy of this press release is furnished as Exhibit 99.1 hereto and is hereby incorporated by reference herein.

*  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 Fourth Quarter and Full Year 2007

Company Reports EPS of $1.53, Cash EPS of $2.15 for Fourth Quarter,

EPS of $4.58, Cash EPS of $6.65 for Full Year 2007

BOSTON, January 30, 2008 – Affiliated Managers Group, Inc. (NYSE: AMG) today reported its financial and operating results for the fourth quarter and full year 2007.

Cash earnings per share (“Cash EPS”) for the fourth quarter of 2007 were $2.15, compared to $1.79 for the fourth quarter of 2006, while diluted earnings per share for the fourth quarter of 2007 were $1.53, compared to $1.21 for the same period of 2006.  Cash Net Income was $81.8 million for the fourth quarter of 2007, compared to $68.6 million for the fourth quarter of 2006.  Net Income for the fourth quarter of 2007 was $60.9 million, compared to $49.0 million for the fourth quarter of 2006.  (Cash EPS and Cash Net Income are defined in the attached tables.)

For the fourth quarter of 2007, revenue was $383.0 million, compared to $328.8 million for the fourth quarter of 2006.  EBITDA for the fourth quarter of 2007 was $132.9 million, compared to $105.2 million for the same period of 2006.

For the year ended December 31, 2007, Cash Net Income was $258.7 million, while EBITDA was $418.2 million.  For the same period, Net Income was $182.0 million, on revenue of $1.4 billion.  For the year ended December 31, 2006, Cash Net Income was $222.5 million, while EBITDA was $342.1 million.  For the same period, Net Income was $151.3 million, on revenue of $1.2 billion.

Net client cash flows for the fourth quarter of 2007 were approximately $(7.2) billion, with flows in the institutional, mutual fund, and high net worth channels of $(6.4) billion, $(500) million, and $(300) million, respectively.  Pro forma for a pending investment, aggregate assets under management were $282.7 billion at December 31, 2007.

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“We reported strong earnings growth for the quarter and full year, with Cash earnings per share of $2.15, an increase of 20%, and $6.65, an increase of 17%, respectively, over the prior year periods,” stated Sean M. Healey, President and Chief Executive Officer.  “We were pleased with our results for the quarter, and although we experienced outflows in some of our quantitative products during a challenging period for many quantitative managers, broadly speaking, our Affiliates generated excellent performance in 2007.  Highlights of the quarter included the strong investment performance of our global and international managers, such as Tweedy, Browne and Genesis, as well as growth equities managers Friess Associates and TimesSquare, which significantly outperformed their benchmarks for the quarter and full year and also attracted new business.”

Mr. Healey continued, “Looking ahead to 2008, notwithstanding recent market volatility, we are in an excellent position to continue to generate strong growth.  Through our Affiliates’ diverse array of outstanding investment products, we actively participate in the industry’s fastest growing and most dynamic areas, such as global and international equities and alternative investment strategies.  We have significantly increased the breadth of our alternative investment products to include more than 40 distinct investment strategies, many of which are relatively uncorrelated with the equity markets.  As we continue to enhance our exposure in this area, we are confident that these products will provide a substantial upside contribution to our earnings going forward.”

“In addition to the ongoing growth of our Affiliates, we made tremendous progress in enhancing our Affiliates’ businesses through the establishment of our global distribution platform,” Mr. Healey added.  “With a distribution office in Sydney, Australia, and the near-term opening of our London office, we are helping our Affiliates attract and serve non-U.S. clients.  Given the early success of this initiative, we continue to identify a number of opportunities worldwide where our boutique investment managers are recognized for their investment expertise and broad appeal to sophisticated investors.”

Mr. Healey concluded, “Finally, the momentum in our new investments area has never been stronger.  We recently completed investments in two outstanding alternative investment managers, ValueAct Capital and BlueMountain Capital Management, and currently have a number of very attractive investment prospects in the pipeline.  With substantial financial capacity, we are confident that we will continue to generate meaningful growth in earnings by executing accretive investments in the highest quality firms.  Through our ongoing discussions with prospective firms, it’s clear that AMG has an established reputation as an innovative and helpful partner to our Affiliates, making us uniquely positioned to execute upon a range of investment opportunities.”

About Affiliated Managers Group, Inc.

AMG is an asset management company with equity investments in a diverse group of boutique investment management firms.  AMG’s strategy is to generate growth through the internal growth of its existing Affiliates, as well as through investments in new Affiliates.  AMG’s innovative transaction structure allows individual members of each Affiliate’s management team to retain or receive significant direct equity ownership in their firm while maintaining operating autonomy.  In addition, AMG provides centralized assistance to its Affiliates in strategic matters, marketing, distribution, product development and operations.  For more information, please visit the Company’s Web site at www.amg.com.

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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, 2006.

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 1-800-366-7449 (domestic calls) or 1-303-262-2191 (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 be available for replay approximately one hour after the conclusion of the call.  To access the replay, please dial 1-800-405-2236 (domestic calls) or 1-303-590-3000 (international calls) and enter the pass code, 11107395#. The live call and the replay of the session, and the additional financial information referenced during the teleconference, may also be accessed via the Web at www.amg.com.

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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)