EXECUTIVE RETENTION PLAN

omissions, wrongful taking, embezzlement, bribery, forgery, counterfeiting or extortion, or (ii) on a felony charge or (iii) on an equivalent charge to those in clauses (i) and (ii) in jurisdictions which do not use those designations; (b) the Participant’s willful or grossly negligent failure to perform duties owed to AMG; (c) the Participant’s willful violation of any securities or commodities laws, any rules or regulations issued pursuant to such laws, or the rules and regulations of any securities or commodities exchange or association of which AMG or any of its subsidiaries or affiliates is a member; or (d) the Participant’s willful violation of any Firm policy concerning hedging or confidential or proprietary information, or material violation of any other Firm policy as in effect from time to time.  The determination as to whether “Cause” has occurred shall be made by the Administrative Committee.  In the event the Administrative Committee believes that a Participant has engaged in of any of Causes (b) through (d) above, the Administrative Committee shall give written notice to such Participant of such Cause with sufficient particularity to permit the Participant to cure such Cause within 30 days following such written notice.  The Administrative Committee shall also have the authority to waive the consequences under the Plan of the existence or occurrence of any of the events, acts or omissions constituting “Cause”.

Section 1.9.             “Change in Control” means the consummation of a merger, consolidation, statutory share exchange or similar form of corporate transaction involving AMG (a “Reorganization”) or sale or other disposition of all or substantially all of AMG’s assets to an entity that is not an affiliate of AMG (a “Sale”), that in each case requires the approval of AMG’s stockholders under the law of AMG’s jurisdiction of organization, whether for such Reorganization or Sale (or the issuance of securities of AMG in such Reorganization or Sale), unless, immediately following such Reorganization or Sale, at least a majority of the members of the board of directors (or similar officials in the case of an entity other than a corporation) of the parent entity (or, if there is no parent entity, the surviving entity) following the consummation of the Reorganization or Sale were, at the time of the Board’s approval of the execution of the initial agreement providing for such Reorganization or Sale, individuals (the “Incumbent Directors”) who either (1) were members of the Board on the Effective Date or (2) became directors subsequent to the Effective Date and whose election or nomination for election was approved by a vote of at least two-thirds of the Incumbent Directors then on the Board (either by a specific vote or by approval of AMG’s proxy statement in which such persons are named as a nominee for director); but provided further that any such individual whose initial assumption of office is in connection with an actual or threatened election contest relating to the election of members of the Board or other actual or threatened solicitation of proxies or consents by or on behalf of a person other than the Board, including by reason of agreement intended to avoid or settle any such actual or threatened contest or solicitation, shall not be considered an Incumbent Director.

Section 1.10.           “Code” means the Internal Revenue Code of 1986, as amended, from time to time.

Section 1.11.           “Disability” means a disability as defined in any long-term disability plan of AMG or, in the absence of such plan, the inability of the Participant to perform the functions of his or her position with AMG for a period of 150 consecutive business days or 200 business days in a period of 365 consecutive days as determined by a physician selected by the Administrative Committee in its reasonable business judgment.

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Section 1.12.           “Effective Date” means November 7, 2005.

Section 1.13.           “Employment” means a Participant’s performance of services for AMG, as determined by the Administrative Committee.  The terms “employ” and “employed” shall have their correlative meanings.

Section 1.14.           “Fair Market Value” means, with respect to Plan Assets on any day, for any security listed on nationally recognized securities exchange, the closing asked price on the most recent day on which such security was traded or, if not so listed, the fair market value as determined in accordance with a valuation methodology approved by the Administrative Committee.

Section 1.15.           “Investment Administrator” means the person or persons appointed by the Administrative Committee with the power to direct the Trustee as to investment of Plan Assets pursuant to the investment elections set forth in each Participant’s executed Award and Election Form.  Each of John Kingston, III and Darrell W. Crate shall have the authority to act singly as the initial Investment Administrator hereunder.

Section 1.16.           “Other Investments Account” means the separate account established in the name of each Participant under Section 4.1 to hold cash (and investments (other than AMG Stock or Affiliate Investments purchased with such cash), in accordance with investment options as approved by the Administrative Committee) and any distribution received with respect to such cash or investments.

Section 1.17.           “Participant” means an employee of AMG who is designated as a Participant by the Administrative Committee pursuant to Article II.

Section 1.18.           “Participant’s Accounts” means a Participant’s AMG Stock Account,  Affiliate Investments Account and Other Investments Account.

Section 1.19.           “Plan” means Affiliated Managers Group, Inc. Executive Retention Plan, as described herein and as hereafter amended from time to time.

Section 1.20.           “Plan Assets” means cash, Stock or other assets contributed to the Trust by AMG and any other assets or instruments into which such contributions are converted pursuant to the Trust, without regard to whether such Plan Assets are held in the Unallocated Account, an AMG Stock Account, an Affiliate Investments Account or an Other Investments Account.

Section 1.21.           “Plan Year” means any calendar year or part thereof beginning on the Effective Date.

Section 1.22.           “Stock” means shares of AMG’s common stock, par value $0.01 per share.

Section 1.23.           “Trust” means the legal entity created by the Trust Agreement.

Section 1.24.           “Trust Agreement” means the agreement, dated as of the Effective Date,

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by and between AMG and the Trustee, including any amendments thereto, setting forth the rights and obligations of the parties thereto in respect of the contributions to and distributions from the Trust, and the establishment and administration of the Accounts pursuant to the Plan.

Section 1.25.           “Trustee” means any corporation, individual or individuals who shall accept the appointment as trustee to execute the duties of the trustee pursuant to the Trust Agreement.

Section 1.26.           “Unallocated Account” means a separate account established under Section 4.1 to hold Plan Assets arising from AMG’s contributions, forfeitures or distributions in respect of such Plan Assets pending the allocation and reallocation of such Plan Assets to the AMG Stock Accounts, Affiliate Investments Accounts or Other Investments Accounts of Participants.

SECTION II.          ELIGIBILITY AND PARTICIPATION

Each employee designated by the Administrative Committee shall become a Participant in the Plan on the date he or she is so designated.  A Participant shall remain a Participant until the date he or she receives a distribution of the entire vested portion of his or her Participant’s Accounts or, if earlier, the date such Participant’s interest in his or her Participant’s Accounts is forfeited in accordance with Article V.

SECTION III.         CONTRIBUTIONS

AMG may irrevocably contribute cash to the Trust from time to time at its sole discretion.

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SECTION IV.        ALLOCATION OF CONTRIBUTIONS

Section 4.1.             Establishment of Accounts .  There shall be established an AMG Stock Account, an Affiliate Investments Account and an Other Investments Account in the name of each Participant and a separate account (the Unallocated Account) to which any forfeitures occurring hereunder may be credited pending allocation to Participants. The Accounts shall also hold any distributions with respect to the Plan Assets held therein until such distributions are payable pursuant to the Plan.

Section 4.2.             Allocations to Participants .  The Administrative Committee shall in its sole discretion designate the total of any contributions and forfeitures allocable to each Participant each Plan Year.  In the absence of a designation by the Administrative Committee as to any Plan Year, the allocation formula of the previous Plan Year shall be used as of the end of such Plan Year, adjusted as follows: any allocation from such previous Plan Year for Plan Participants whose accounts were forfeited pursuant to Section 5.5 or who are no longer employees of AMG shall be allocated among the remaining Participants such that the ratio of allocations relating to the previous Plan Year among such remaining Participants is preserved.  The Investment Administrator shall direct the Trustee to invest such amounts among each Participant’s Accounts pursuant to investment directions given by Participants on an Award and Election Form provided by the Company, in the form attached hereto and accepted by the Administrative Committee.

Section 4.3.             Investment .  The AMG Stock Account shall be invested solely in shares of AMG Stock that the Trustee shall purchase from AMG or pursuant to open market transactions with any cash contribution made by AMG.  The Affiliate Investments Account shall be invested by the Trustee in such Affiliate Investments as directed by the Investment Administrator from cash contributions made by AMG.  The Other Investments Account shall be invested by the Trustee in cash or investments (other than AMG Stock or Affiliate Investments) as directed by the Investment Administrator from cash contributions made by AMG.

Section 4.4.             Voting of Stock; Tender or Exchange Offers .  With respect to the Plan Assets allocated to Participant’s Accounts, each Participant shall be entitled to instruct the Trustee, on a confidential basis (a) as to the manner in which the Trustee’s rights will be exercised with respect to any matter which involves the voting or other similar rights attached to such Plan Assets, (b) in the event of a tender or exchange offer for all or substantially all of the Stock of AMG, whether such Stock shall be tendered or exchanged by the Trustee, and (c) in the event of a tender or exchange offer for all or substantially all of the stock or securities of a person other than AMG (or its affiliates), whether such Stock shall be tendered or exchanged by the Trustee.  Without limiting the foregoing, the Trust Agreement shall provide that the Trustee shall have no discretion and shall be required to vote, tender or exchange Plan Assets held by the Trust as follows:  (i) Plan Assets allocated to Participant’s Accounts shall be voted, tendered or exchanged, as applicable, in accordance with any instructions received from such Participant or

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such Participant’s authorized representative pursuant to a duly executed power of attorney or similar instrument, (ii) Plan Assets held in Participant’s Accounts with respect to which the Trustee does not receive instructions shall not be voted, tendered or exchanged, as applicable, and (iii) Plan Assets held in the Unallocated Account shall be voted, tendered or exchanged, as applicable, in the same proportion as the applicable Plan Assets allocated to Participant’s Accounts with respect to which instructions are received by the Trustee are voted, tendered or exchanged.

SECTION V.          VESTING

Section 5.1.             Vesting. Unless otherwise set forth in such Participant’s Award and Election Form, a Participant’s interest in his or her AMG Stock Account, Affiliate Investments Account and Other Investments Account shall vest in four equal annual increments of twenty-five percent (25%) commencing on the first day of the new calendar year following the one year anniversary of the date of grant.  Subject to the determination of the Administrative Committee, vesting of stock in the AMG Stock Account or Affiliate Investments Account shall be subject to rounding to avoid the vesting of fractional shares.

Section 5.2.             Deferral.  No Participant shall be permitted to defer the vesting of Accounts that would otherwise vest pursuant to the terms of this Section V.

Section 5.3.             Vesting of Forfeitures.  Forfeitures allocated among Participants pursuant to Section 5.5 shall vest in accordance with Section 5.1, unless otherwise decided by the Administrative Committee.

Section 5.4.             Special Rule.  Notwithstanding any other pro