UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 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 29, 2013

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 Condition.

On January 29, 2013, 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, 2012.  A copy of this press release is furnished as Exhibit 99.1 hereto.

ITEM 8.01                                  Other Events.

The financial statement tables set forth in the press release issued by the Company on January 29, 2013 are also filed as Exhibit 99.2 hereto and are incorporated by reference herein.

ITEM 9.01                                  Financial Statements and Exhibits.

(d)                                 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 2012

Company Reports Economic EPS of $2.55; EPS of $1.40 for Fourth Quarter,

Economic EPS of $7.71; EPS of $3.28 for Full Year 2012

BOSTON, January 29, 2013 — Affiliated Managers Group, Inc. (NYSE: AMG) today reported its financial and operating results for the fourth quarter and full year 2012.

For the fourth quarter of 2012, Economic earnings per share (“Economic EPS”) were $2.55, compared to $1.76 for the same period of 2011, while diluted earnings per share for the fourth quarter of 2012 were $1.40, compared to $0.77 for the same period of 2011.  For the fourth quarter of 2012, Economic net income was $136.5 million, compared to $92.5 million for the same period of 2011.  For the fourth quarter of 2012, Net income was $75.0 million, compared to $40.3 million for the same period of 2011.  For the fourth quarter of 2012, EBITDA was $182.1 million, compared to $116.3 million for the same period of 2011.  (Economic EPS, Economic net income, and EBITDA are defined in the attached tables, along with comparisons to the appropriate GAAP measure.)

For the year ended December 31, 2012, Economic net income was $408.8 million, while EBITDA was $543.4 million, and Net income was $174.0 million.  For the year ended December 31, 2011, Economic net income was $351.0 million, while EBITDA was $471.3 million, and Net income was $164.9 million.

Net client cash flows for the fourth quarter of 2012 were $5.1 billion, and flows for the year ended December 31, 2012 were $30.1 billion. The aggregate assets under management of AMG’s affiliated investment management firms were approximately $432 billion at December 31, 2012.

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“AMG’s results for the fourth quarter and full year 2012 reflected strong performance across all areas of our business and the excellent execution of our growth strategy, including continued outstanding growth from net client cash flows, the ongoing expansion of our global distribution platform, and the significant deployment of capital through our new investments strategy,” stated Sean M. Healey, Chairman and Chief Executive Officer of AMG.  “Our Economic earnings per share were a record $7.71 for the year, an increase of 16% over 2011, and going forward, we see excellent opportunities to generate further growth in earnings and shareholder value through both the organic growth of our Affiliates as well as the addition of outstanding new Affiliates.”

“Our Affiliates produced strong investment performance in the areas which are most attractive to global clients for the alpha-generating portions of their portfolios, including global and emerging markets equities and alternatives, which collectively generate over 70% of our EBITDA,” Mr. Healey added.  “With industry-leading long-term track records in these product areas at Affiliates such as Tweedy, Browne, Harding Loevner, and Genesis in equities, and ValueAct, AQR, and BlueMountain in alternatives, we are well-positioned for continued strong organic growth.  In addition, our alternative products delivered excellent absolute returns and meaningful performance fees during the year.”

Mr. Healey continued, “Our global distribution strategy, which complements Affiliate-level marketing efforts with the centralized platform of AMG’s global franchise, has now generated exceptional organic growth from net client cash flows for eleven consecutive quarters — including over $30 billion of net client cash flows in 2012, a period in which investor risk appetite remained broadly muted.  The strategic investment we have made over the past five years in extending the breadth and depth of our Affiliates’ marketing reach around the globe has generated substantial incremental new business in every coverage region, and with new offices in Dubai and Zurich and additional resources in Germany and Switzerland within the past year, we expect continued momentum going forward.  Given the increasing client demand for differentiated, alpha-generating strategies from specialist firms, and the significant opportunities we see to win new business and market share around the world, we will continue to add capabilities in key markets and channels globally in 2013.”

“Finally, we were very pleased with the successful execution of our new investments strategy in 2012, with the addition of Veritable, Yacktman, and our significant additional investment in BlueMountain,” Mr. Healey concluded. “Our forward new investment pipeline is strong and diverse, and includes traditional, alternative, and wealth management firms globally.  We are making excellent progress in this area as we actively evaluate an array of prospective Affiliates, and we will continue to benefit from our reputation as the partner of choice to the best boutique firms around the world.  Given AMG’s unique competitive position and our outstanding track record of Affiliate investments, we are confident in our ability to add materially to our earnings growth through accretive Affiliate investments going forward.”

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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 Affiliates in strategic matters, marketing, distribution, product development and operations.  As of December 31, 2012, the aggregate assets under management of AMG’s Affiliates were approximately $432 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 “Risk Factors” set forth in the Company’s Form 10-K for the year ended December 31, 2011.

AMG routinely posts information that may be significant for investors in the Investor Relations 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 conference ID 407209.  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

(in millions, except per share data)

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Affiliated Managers Group, Inc.

Financial Highlights

(in millions, except per share data)

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Affiliated Managers Group, Inc.

Reconciliations of Earnings Per Share Calculation

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Affiliated Managers Group, Inc.

Reconciliations of Average Shares Outstanding

(in millions)

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Affiliated Managers Group, Inc.

Operating Results

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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

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Financial Results

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Affiliated Managers Group, Inc.

Reconciliations of Performance and Liquidity Measures

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Affiliated Managers Group, Inc.

Consolidated Statements of Income

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Affiliated Managers Group, Inc.

Consolidated Balance Sheets

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Affiliated Managers Group, Inc.

Consolidated Statements of Cash Flow

(in millions)