<PAGE>

                                                                     Exhibit 4.8

================================================================================

                         AFFILIATED MANAGERS GROUP, INC.

                            (a Delaware corporation)

                          Liquid Yield Option(TM) Notes
                                 Due May 7, 2021
                             (Zero Coupon - Senior)

                               PURCHASE AGREEMENT

Dated: As of May 1, 2001

================================================================================

(TM) Trademark of Merrill Lynch & Co., Inc.

<PAGE>

                                Table of Contents

                                                                            Page
                                                                            ----

SECTION 1.  Representations and Warranties.....................................3
      (a)   Representations and Warranties by the Company......................3
            (i)      Offering Memorandum.......................................3
            (ii)     Incorporated Documents....................................3
            (iii)    Independent Accountants...................................3
            (iv)     Financial Statements......................................3
            (v)      No Material Adverse Change in Business....................4
            (vi)     Good Standing of the Company..............................4
            (vii)    Good Standing of Subsidiaries.............................4
            (viii)   Capitalization............................................5
            (ix)     Authorization of Agreement and the Registration Rights
                     Agreement.................................................5
            (x)      Authorization of the Indenture............................5
            (xi)     Authorization of the Securities...........................5
            (xii)    Description of the Securities and the Indenture...........6
            (xiii)   Authorization and Description of Common Stock.............6
            (xiv)    Absence of Defaults and Conflicts.........................6
            (xv)     Absence of Labor Dispute..................................7
            (xvi)    Absence of Proceedings....................................7
            (xvii)   Accuracy of Exhibits......................................7
            (xviii)  Possession of Intellectual Property.......................7
            (xix)    Absence of Further Requirements...........................7
            (xx)     Possession of Licenses and Permits........................8
            (xxi)    Title to Property.........................................8
            (xxii)   Investment Company Act....................................8
            (xxiii)  Environmental Laws........................................8
            (xxiv)   No Integration............................................9
            (xxv)    Rule 144A.................................................9
            (xxvi)   No General Solicitation or General Advertising............9
            (xxvii)  No Registration Required..................................9
            (xxviii) Adviser Activities and Broker-Dealer Business............10
            (xxix)   Compliance with Laws.....................................10
            (xxx)    Registration of Funds....................................11
            (xxxi)   Agreements...............................................11
      (b)   Officer's Certificates............................................12

SECTION 2.  Sale and Delivery to Initial Purchaser; Closing...................12
      (a)   Initial Securities................................................12
      (b)   Option Securities.................................................12
      (c)   Payment...........................................................12
      (d)   Denominations; Registration.......................................13
      (e)   Qualification of Initial Purchaser................................13
<PAGE>

SECTION 3.  Covenants of the Company..........................................13
      (a)   Delivery of Offering Memorandum...................................13
      (b)   Filings; Material Changes.........................................13
      (c)   Amendments and Supplements........................................14
      (d)   Blue Sky Qualifications...........................................14
      (e)   Use of Proceeds...................................................14
      (f)   Restriction on Sale of Common Stock...............................15
      (g)   No Integration....................................................15
      (h)   Rule 144A Information.............................................15
      (i)   No Purchases......................................................15
      (j)   PORTAL............................................................15
      (k)   Reasonable Inquiries; Information.................................16
      (l)   Registration Rights Agreement; Trust Indenture Act................16

SECTION 4.  Payment of Expenses...............................................16
      (a)   Expenses..........................................................16
      (b)   Termination of Agreement..........................................16

SECTION 5.  Conditions of Initial Purchaser's Obligations.....................16
      (a)   Opinion of Counsel for Company....................................16
      (b)   Opinion of Counsel for Initial Purchaser..........................17
      (c)   Officers' Certificate.............................................17
      (d)   Accountant's Comfort Letter.......................................17
      (e)   Bring-down Comfort Letter.........................................17
      (f)   PORTAL Market.....................................................17
      (g)   Maintenance of Rating.............................................18
      (h)   Lock-up Agreements................................................18
      (i)   Indenture and Registration Rights Agreement.......................18
      (j)   Conditions to Purchase of Option Securities.......................18
            (i)   Officers' Certificate.......................................18
            (ii)  Opinion of Counsel for Company..............................18
            (iii) Opinion of Counsel for Initial Purchaser....................18
            (iv)  Bring-down Comfort Letter...................................19
            (v)   No Downgrading..............................................19
      (k)   Additional Documents..............................................19
      (l)   Termination of Agreement..........................................19

SECTION 6.  Subsequent Offers and Resales of the Securities...................19

SECTION 7.  Indemnification...................................................20
      (a)   Indemnification of Initial Purchaser..............................20

SECTION 8.  Contribution......................................................22


                                       ii
<PAGE>

SECTION 9.  Termination of Agreement..........................................24
      (a)   Termination; General..............................................24
      (b)   Liabilities.......................................................24

SECTION 10. Notices...........................................................24

SECTION 11. Parties...........................................................24

SECTION 12. GOVERNING LAW AND TIME............................................25

SECTION 13. Effect of Headings................................................25


                                      iii
<PAGE>

                         AFFILIATED MANAGERS GROUP, INC.

                            (a Delaware corporation)

                                  $195,000,000

                          Liquid Yield Option(TM) Notes
                                 Due May 7, 2021
                             (Zero Coupon - Senior)

                               PURCHASE AGREEMENT

                                                               As of May 1, 2001

MERRILL LYNCH & CO.
Merrill Lynch, Pierce, Fenner & Smith
             Incorporated
North Tower
World Financial Center
New York, New York  10281-1209

Ladies and Gentlemen:

      Affiliated Managers Group, Inc., a Delaware corporation (the "Company"),
confirms its agreement with Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner &
Smith Incorporated (the "Initial Purchaser"), with respect to the issue and sale
by the Company and the purchase by the Initial Purchaser, of $195,000,000
aggregate principal amount at maturity of the Company's Liquid Yield OptionTM
Notes Due May 7, 2021 (Zero Coupon - Senior) (the "LYONs"), and with respect to
the grant by the Company to the Initial Purchaser of the option described in
Section 2(b) hereof to purchase all or any part of an additional $56,000,000
aggregate principal amount at maturity of LYONs to cover over-allotments, if
any. The aforesaid $195,000,000 aggregate principal amount at maturity of LYONs
(the "Initial Securities") to be purchased by the Initial Purchaser and all or
any part of the $56,000,000 aggregate principal amount at maturity of LYONs
subject to the option described in Section 2(b) hereof (the "Option Securities")
are hereinafter called, collectively, the "Securities." The Securities are to be
issued pursuant to a senior indenture, to be dated as of May 7, 2001 (the
"Indenture"), between the Company and First Union National Bank, as trustee (the
"Trustee").

      The Securities are convertible at the option of the holder at any time on
or prior to maturity (unless previously redeemed or otherwise purchased) into
shares of common stock, par

----------
(TM) Trademark of Merrill Lynch & Co., Inc.

<PAGE>

value $0.01 per share, of the Company (the "Common Stock") in accordance with
the terms of the Securities and the Indenture, at the initial conversion rate of
11.6195 shares of Common Stock per LYON. Securities issued in book-entry form
will be issued to Cede & Co. as nominee of The Depository Trust Company ("DTC")
pursuant to a letter agreement, to be dated as of the Closing Time (as defined
in Section 2(c)), among the Company, the Trustee and DTC.

      The Company understands that the Initial Purchaser proposes to make an
offering of the Securities on the terms and in the manner set forth herein and
agrees that the Initial Purchaser may resell, subject to the conditions set
forth herein, all or a portion of the Securities to purchasers ("Subsequent
Purchasers") at any time after the date of this Agreement. The Securities are to
be sold to the Initial Purchaser and offered and resold by the Initial Purchaser
without being registered under the Securities Act of 1933, as amended (the "1933
Act"), in reliance upon exemptions therefrom. Pursuant to the terms of the
Securities and the Indenture, investors that acquire Securities may only resell
or otherwise transfer such Securities if such Securities are hereafter
registered under the 1933 Act or pursuant to an available exemption from the
registration requirements of the 1933 Act (including the exemption afforded by
Rule 144A ("Rule 144A") of the rules and regulations promulgated under the 1933
Act by the Securities and Exchange Commission (the "Commission")). On or prior
to the Closing Time, the Company will enter into with the Initial Purchaser an
agreement (the "Registration Rights Agreement") pursuant to which, subject to
the conditions set forth therein, the Company is required to file and use its
reasonable efforts to have declared effective a registration statement under the
1933 Act to register resales of the LYONs and the shares of Common Stock
issuable upon conversion thereof.

      The Company has prepared and delivered to the Initial Purchaser copies of
a preliminary offering memorandum (the "Preliminary Offering Memorandum") and
has prepared and will deliver to the Initial Purchaser, on the date hereof,
copies of a final offering memorandum dated May 1, 2001 (the "Final Offering
Memorandum"), each to be used by the Initial Purchaser in connection with its
solicitation of purchases of, or offering of, the Securities. "Offering
Memorandum" means, with respect to any date or time referred to in this
Agreement, the most recent offering memorandum (whether the Preliminary Offering
Memorandum or the Final Offering Memorandum, or any amendment or supplement to
either such document), including exhibits thereto and any documents incorporated
therein by reference, which has been prepared and delivered by the Company to
the Initial Purchaser in connection with its solicitation of purchases of, or
offering of, the Securities.

      All references in this Agreement to financial statements and schedules and
other information which is "contained," "included," "stated" or "described" in
the Offering Memorandum shall be deemed to mean and include all such financial
statements and schedules and other information which are expressly incorporated
by reference in the Offering Memorandum; and all references in this Agreement to
amendments or supplements to the Offering Memorandum shall be deemed to mean and
include the filing of any document under the Securities Exchange Act of 1934
(the "1934 Act") which are expressly incorporated by reference in the Offering
Memorandum.


                                       2
<PAGE>

SECTION 1. Representations and Warranties.

      (a) Representations and Warranties by the Company. The Company represents
and warrants to the Initial Purchaser as of the date hereof, as of the Closing
Time referred to in Section 2(c) hereof, and as of each Date of Delivery (if
any) referred to in Section 2(b) hereof, and agrees with the Initial Purchaser,
as follows:

            (i) Offering Memorandum. The Offering Memorandum does not, and at
      the Closing Time referred to in Section 2 (and, if any Option Securities
      are purchased, at the Date of Delivery) will not, include an untrue
      statement of a material fact or omit to state a material fact necessary in
      order to make the statements therein, in the light of the circumstances
      under which they were made, not misleading. The representations and
      warranties in this subsection shall not apply to statements in or
      omissions from the Offering Memorandum made in reliance upon and in
      conformity with information furnished to the Company in writing by the
      Initial Purchaser expressly for use in the Offering Memorandum.

            (ii) Incorporated Documents. The documents incorporated by reference
      in the Offering Memorandum (the "Incorporated Documents"), at the time
      they were or hereafter are filed with the Commission, complied and will
      comply in all material respects with the requirements of the 1934 Act and
      the rules and regulations of the Commission thereunder (the "1934 Act
      Regulations"), and, when read together with the other information in the
      Offering Memorandum, at the date of the Offering Memorandum and at the
      Closing Time (and if any Option Securities are purchased, at the Date of
      Delivery), did not and will not contain an untrue statement of a material
      fact or omit to state a material fact required to be stated therein or
      necessary to make the statements therein not misleading.

            (iii) Independent Accountants. The accountants who certified the
      financial statements and supporting schedules included in the Offering
      Memorandum are independent public accountants as required by the 1933 Act
      and the regulations of the Commission thereunder (the "1933 Act
      Regulations").

            (iv) Financial Statements. The financial statements included in or
      incorporated into the Offering Memorandum, together with the related
      schedules and notes, present fairly the financial position of the Company
      and its consolidated subsidiaries at the dates indicated and the statement
      of operations, stockholders' equity and cash flows of the Company and its
      consolidated subsidiaries for the periods specified; said financial
      statements have been prepared in conformity with generally accepted
      accounting principles ("GAAP") applied on a consistent basis throughout
      the periods involved, except as stated therein. The supporting schedules
      incorporated by reference in the Offering Memorandum present fairly in
      accordance with GAAP the information required to be stated in the
      Incorporated Documents. The selected financial data and the summary
      financial information included in the Offering Memorandum present fairly
      the


                                       3
<PAGE>

      information shown therein and have been compiled on a basis consistent in
      all material respects with that of the audited financial statements
      included in or incorporated by reference in the Offering Memorandum.

            (v) No Material Adverse Change in Business. Since the respective
      dates as of which information is given in the Offering Memorandum, except
      as otherwise stated therein, (A) there has been no material adverse change
      or prospective material adverse change in the business, management,
      financial position, stockholders equity or results of operations of the
      Company and its subsidiaries considered as one enterprise, whether or not
      arising in the ordinary course of business (a "Material Adverse Effect"),
      and (B) there have been no transactions entered into by the Company or any
      of its subsidiaries, other than those in the ordinary course of business,
      which are material with respect to the Company and its subsidiaries
      considered as one enterprise, and there has been no dividend or
      distribution of any kind declared, paid or made by the Company on any
      class of its capital stock.

            (vi) Good Standing of the Company. The Company has been duly
      organized and is validly existing as a corporation in good standing under
      the laws of the State of Delaware and has corporate power and authority to
      own, lease and operate its properties and to conduct its business as
      described in the Offering Memorandum and to enter into and perform its
      obligations under, or as contemplated by, this Agreement. The Company is
      duly qualified as a foreign corporation to transact business and is in
      good standing in each other jurisdiction in which such qualification is
      required, whether by reason of the ownership or leasing of property or the
      conduct of business, except where the failure so to qualify or to be in
      good standing would not result in a Material Adverse Effect.

            (vii) Good Standing of Subsidiaries. Each subsidiary of the Company
      has been duly organized or formed and is validly existing as a
      corporation, limited partnership, limited liability company, Massachusetts
      business trust or general partnership, as the case may be, under the laws
      of its jurisdiction of organization and is in good standing under the laws
      of its jurisdiction of organization, has power (corporate or otherwise)
      and authority to own, lease and operate its properties and to conduct its
      business as described in the Offering Memorandum or in the Incorporated
      Documents and is duly qualified as a foreign corporation, limited
      partnership, limited liability company, Massachusetts business trust or
      general partnership, as the case may be, to transact business and is in
      good standing in each jurisdiction in which such qualification is
      required, whether by reason of the ownership or leasing of property or the
      conduct of business, except where the failure to so qualify or to be in
      good standing would not result in a Material Adverse Effect. Except as
      otherwise disclosed in the Offering Memorandum or in the Incorporated
      Documents, all of the issued shares of capital stock of each subsidiary of
      the Company which is a corporation, have been duly authorized and validly
      issued, and are fully paid and non-assessable, and (except for directors'
      qualifying shares and as described generally in the Offering Memorandum
      and in the Incorporated Documents) are owned directly or indirectly by the
      Company, free and clear of all liens,


                                       4
<PAGE>

      encumbrances, equities or claims, in each case with such exceptions,
      individually or in the aggregate, as would not have a Material Adverse
      Effect. The partnership interests, membership interests and shares of
      beneficial interest of each subsidiary of the Company which is a
      partnership, limited liability company or Massachusetts business trust
      have been validly issued in accordance with applicable law and the
      partnership agreement, limited liability agreement or declaration of
      trust, as applicable, of such subsidiary, and (except as described
      generally in the Offering Memorandum or in the Incorporated Documents) are
      owned directly or indirectly by the Company, free and clear of all liens,
      encumbrances, equities or claims, except, in the case of each subsidiary
      of the Company, for liens, encumbrances, equities or claims which
      individually or in the aggregate would not be material to the Company's
      ownership of such subsidiary or to the Company's exercise of its rights
      with respect to such subsidiary; and none of the outstanding shares of
      capital stock, partnership interests, membership interests or shares of
      beneficial interests, as the case may be, of any subsidiary was issued in
      violation of the preemptive or similar rights of any securityholder of
      such subsidiary.

            (viii) Capitalization. The authorized, issued and outstanding shares
      of capital stock of the Company are as set forth in the Offering
      Memorandum in the column entitled "Actual" under the caption
      "Capitalization" (except for subsequent issuances, if any, pursuant to
      this Agreement, pursuant to reservations, agreements or employee benefit
      plans referred to in the Offering Memorandum or in the Incorporated
      Documents or pursuant to the exercise of convertible securities or options
      referred to in the Offering Memorandum or in the Incorporated Documents).
      The shares of issued and outstanding capital stock of the Company have
      been duly authorized and validly issued and are fully paid and
      non-assessable; none of the outstanding shares of capital stock of the
      Company was issued in violation of the preemptive or other similar rights
      of any securityholder of the Company.

            (ix) Authorization of Agreement and the Registration Rights
      Agreement. This Agreement has been, and at or prior to the Closing Time,
      the Registration Rights Agreement will have been, duly authorized,
      executed and delivered by the Company.

            (x) Authorization of the Indenture. The Indenture has been duly
      authorized by the Company and, when duly executed and delivered by the
      Company and the Trustee, will constitute a valid and binding agreement of
      the Company, enforceable against the Company in accordance with its terms,
      except as the enforcement thereof may be limited by bankruptcy,
      insolvency, reorganization, moratorium or other similar laws relating to
      or affecting creditors' rights generally or by general equitable
      principles.

            (xi) Authorization of the Securities. The Securities have been duly
      authorized and, at the Closing Time, will have been duly executed by the
      Company and, when authenticated, issued and delivered in the manner
      provided for in the Indenture and delivered against payment of the
      purchase price therefor as provided in this Agreement, will constitute
      valid and binding obligations of the Company, enforceable against the


                                       5
<PAGE>

      Company in accordance with their terms, except as the enforcement thereof
      may be limited by bankruptcy, insolvency, reorganization, moratorium or
      other similar laws relating to or affecting creditors' rights generally or
      by general equitable principles.

            (xii) Description of the Securities and the Indenture. The
      description of the Securities and the Indenture set forth in the Offering
      Memorandum is correct in all material respects.

            (xiii) Authorization and Description of Common Stock. The Common
      Stock conforms to all statements relating thereto incorporated by
      reference in the Offering Memorandum, and such description conforms in all
      material respects to the rights set forth in the instruments defining the
      same. Upon issuance and delivery of the Securities in accordance with this
      Agreement and the Indenture, the Securities will be convertible at the
      option of the holder thereof for shares of Common Stock in accordance with
      the terms of the Securities and the Indenture; the shares of Common Stock
      issuable upon conversion of the Securities have been duly authorized and
      reserved for issuance upon such conversion by all necessary corporate
      action and such shares, when issued upon such conversion, will be validly
      issued and will be fully paid and non-assessable; and the issuance of such
      shares upon such conversion will not be subject to the preemptive or other
      similar rights of any securityholder of the Company.

            (xiv) Absence of Defaults and Conflicts. Neither the Company nor any
      of its subsidiaries is in violation of its charter or by-laws or other
      constituting or organizational document or in default in the performance
      or observance of any obligation, agreement, covenant or condition
      contained in any contract, indenture, mortgage, deed of trust, loan or
      credit agreement, note, lease or other agreement or instrument to which
      the Company or any of its subsidiaries is a party or by which it or any of
      them may be bound, or to which any of the property or assets of the
      Company or any subsidiary is subject (collectively, "Agreements and
      Instruments") except for such defaults that would not result in a Material
      Adverse Effect; and the execution, delivery and performance of this
      Agreement, the Registration Rights Agreement, the Indenture and the
      Securities and the consummation of the transactions contemplated herein
      and in the Offering Memorandum (including the issuance and sale of the
      Securities and the use of the proceeds from the sale of the Securities as
      described in the Offering Memorandum under the caption "Use of Proceeds"
      and the issuance of the shares of Common Stock issuable upon conversion of
      the Securities) and compliance by the Company with its obligations
      hereunder, and under the Indenture, the Registration Rights Agreement and
      the Securities, have been duly authorized by all necessary corporate
      action and do not, whether with or without the giving of notice or passage
      of time or both, conflict with or constitute a breach of, or default or
      Repayment Event (as defined below) under, or result in the creation or
      imposition of any lien, charge or encumbrance upon any property or assets
      of the Company or any subsidiary pursuant to, the Agreements and
      Instruments (except for such conflicts, breaches or defaults or liens,
      charges or encumbrances that would not result in a Material Adverse
      Effect), nor will such action result in any violation of the provisions of


                                       6
<PAGE>

      the charter or by-laws or other constituting or organizational instrument
      as in effect on the date hereof of the Company or any subsidiary or any
      applicable law, statute, rule, regulation, judgment, order, writ or decree
      of any government, government instrumentality or court, domestic or
      foreign, having jurisdiction over the Company or any subsidiary or any of
      their assets, properties or operations, except for any such violation of
      any applicable law, statute, rule, regulation, judgment, order, writ or
      decree of law which would not result in a Material Adverse Effect. As used
      herein, a "Repayment Event" means any event or condition which gives the
      holder of any note, debenture or other evidence of indebtedness (or any
      person acting on such holder's behalf) the right to require the
      repurchase, redemption or repayment of all or a portion of such
      indebtedness by the Company or any subsidiary.

            (xv) Absence of Labor Dispute. No labor dispute with the employees
      of the Company or any subsidiary exists or, to the knowledge of the
      Company, is imminent.

            (xvi) Absence of Proceedings. Except as disclosed in the Offering
      Memorandum or in the Incorporated Documents, there is no action, suit,
      proceeding, inquiry or investigation before or brought by any court or
      governmental agency or body, domestic or foreign, now pending, or, to the
      knowledge of the Company, threatened, against or affecting the Company or
      any subsidiary, which, singly or in the aggregate, would reasonably be
      expected to result in a Material Adverse Effect, or which would reasonably
      be expected to materially and adversely affect the consummation of the
      transactions contemplated in this Agreement or the performance by the
      Company of its obligations hereunder.

            (xvii) Accuracy of Exhibits. All of the descriptions of contracts or
      other documents contained or incorporated by reference in the Offering
      Memorandum are accurate and complete descriptions in all material respects
      of such contracts or other documents.

            (xviii) Possession of Intellectual Property. The Company and its
      subsidiaries own or possess the intellectual property necessary to carry
      on the business now operated by them, and neither the Company nor, to the
      best of the Company's knowledge, any of its subsidiaries has received any
      notice or is otherwise aware of any infringement of or conflict with
      asserted rights of others with respect to any such intellectual property
      or of any facts or circumstances which would render any such intellectual
      property invalid or inadequate to protect the interest of the Company or
      any of its subsidiaries therein, and which infringement or conflict (if
      the subject of any unfavorable decision, ruling or finding) or invalidity
      or inadequacy, singly or in the aggregate, would result in a Material
      Adverse Effect.

            (xix) Absence of Further Requirements. No filing with, or
      authorization, approval, consent, license, order, registration,
      qualification or decree of, any court or governmental authority or agency
      is necessary or required for the performance by the


                                       7
<PAGE>

      Company of its obligations hereunder or under the Registration Rights
      Agreement or the Indenture, in connection with the offering, issuance or
      sale of the Securities hereunder, the issuance of shares of Common Stock
      upon conversion of Securities or the consummation of the transactions
      contemplated by this Agreement, or for the due execution, delivery or
      performance of the Agreement, the Registration Rights Agreement or the
      Indenture, except such as have been already obtained or as may be required
      under the 1933 Act or the 1933 Act Regulations in connection with the
      transactions contemplated by the Registration Rights Agreement or state
      securities laws and except for the qualification of the Indenture under
      the 1939 Act.

            (xx) Possession of Licenses and Permits. The Company and its
      subsidiaries possess such permits, licenses, approvals, consents and other
      authorizations (collectively, "Governmental Licenses") issued by the
      appropriate federal, state, local or foreign regulatory agencies or bodies
      necessary to conduct the business now operated by them; the Company and
      its subsidiaries are in compliance with the terms and conditions of all
      such Governmental Licenses, except in any such case where the failure to
      so possess or to comply would not, singly or in the aggregate, have a
      Material Adverse Effect; all of the Governmental Licenses are valid and in
      full force and effect, except where the invalidity of such Governmental
      Licenses or the failure of such Governmental Licenses to be in full force
      and effect would not have a Material Adverse Effect; and neither the
      Company nor any of its subsidiaries has received any notice of proceedings
      relating to the revocation or modification of any such Governmental
      Licenses which, singly or in the aggregate, if the subject of an
      unfavorable decision, ruling or finding, would result in a Material
      Adverse Effect.

            (xxi) Title to Property. The Company and its subsidiaries have good
      and marketable title to all real property owned by the Company and its
      subsidiaries and good title to all other properties owned by them, in each
      case, free and clear of all mortgages, pledges, liens, security interests,
      claims, restrictions or encumbrances of any kind except such as (a) are
      described in the Offering Memorandum or (b) would not, singly or in the
      aggregate, result in a Material Adverse Effect; and all of the leases and
      subleases material to the business of the Company and its subsidiaries,
      considered as one enterprise, and under which the Company or any of its
      subsidiaries holds properties described in the Offering Memorandum or in
      the Incorporated Documents, are in full force and effect, and neither the
      Company nor any subsidiary has any notice of any material claim of any
      sort that has been asserted by anyone adverse to the rights of the Company
      or any subsidiary under any of the leases or subleases mentioned above, or
      affecting or questioning the rights of the Company or such subsidiary to
      the continued possession of the leased or subleased premises under any
      such lease or sublease.

            (xxii) Investment Company Act. Neither the Company nor any of its
      subsidiaries are, and upon the issuance and sale of the Securities as
      herein contemplated and the application of the net proceeds therefrom as
      described in the Offering Memorandum will be, an "investment company" or
      an entity "controlled" by an


                                       8
<PAGE>

      "investment company" as such terms are defined in the Investment Company
      Act of 1940, as amended (the "1940 Act").

            (xxiii) Environmental Laws. Except as described in the Offering
      Memorandum or in the Incorporated Documents and except as would not,
      singly or in the aggregate, result in a Material Adverse Effect, (A)
      neither the Company nor any of its subsidiaries is in violation of any
      federal, state, local or foreign statute, law, rule, regulation,
      ordinance, code, policy or rule of common law or any judicial or
      administrative interpretation thereof, including any judicial or
      administrative order, consent, decree or judgment, relating to pollution
      or protection of human health, the environment (including, without
      limitation, ambient air, surface water, groundwater, land surface or
      subsurface strata) or wildlife, including, without limitation, laws and
      regulations relating to the release or threatened release of chemicals,
      pollutants, contaminants, wastes, toxic substances, hazardous substances,
      petroleum or petroleum products (collectively, "Hazardous Materials") or
      to the manufacture, processing, distribution, use, treatment, storage,
      disposal, transport or handling of Hazardous Materials (collectively,
      "Environmental Laws"), (B) the Company and its subsidiaries have all
      permits, authorizations and approvals required under any applicable
      Environmental Laws and are each in compliance with their requirements, (C)
      there are no pending or, to the best knowledge of the Company, threatened
      administrative, regulatory or judicial actions, suits, demands, demand
      letters, claims, liens, notices of noncompliance or violation,
      investigation or proceedings relating to any Environmental Law against the
      Company or any of its subsidiaries, and (D) to the best knowledge of the
      Company, there are no events or circumstances that might reasonably be
      expected to form the basis of an order for clean-up or remediation, or an
      action, suit or proceeding by any private party or governmental body or
      agency, against or affecting the Company or any of its subsidiaries
      relating to Hazardous Materials or the violation of any Environmental
      Laws.

            (xxiv) No Integration. The Company has not, directly or indirectly,
      solicited any offer to buy or offered to sell, and will not, directly or
      indirectly, solicit any offer to buy or offer to sell, in the United
      States or to any United States citizen or resident, any security which is
      or would be integrated with the sale of the Securities in a manner that
      would require the Securities to be registered under the 1933 Act.

            (xxv) Rule 144A. The Securities are eligible for resale pursuant to
      Rule 144A and will not for purposes of Rule 144A(d)(3)(i) be, at the
      Closing Time, of the same class as securities listed on a national
      securities exchange registered under Section 6 of the 1934 Act, or quoted
      in a U.S. automated interdealer quotation system.

            (xxvi) No General Solicitation or General Advertising. None of the
      Company, its affiliates (as defined in Rule 501(b) under the 1933 Act) or
      any person (other than the Initial Purchaser and its respective
      affiliates, as to whom the Company makes no representation) acting on its
      behalf has or shall offer or sell the Securities by any form of general
      solicitation or general advertising within the meaning of Rule 502(c)
      under


                                       9
<PAGE>

      Regulation D of the 1933 Act.

            (xxvii) No Registration Required. Subject to compliance by the
      Initial Purchaser with the representations and warranties set forth in
      Section 2 and the procedures set forth in Section 6 hereof, the compliance
      of the Initial Purchaser with the offering and transfer procedures and
      restrictions described in the Offering Memorandum, the accuracy of the
      representations and warranties made in accordance with the Purchase
      Agreement and the Offering Memorandum by purchasers to whom the Initial
      Purchaser initially resells LYONs and the condition that Subsequent
      Purchasers receive a copy of the Offering Memorandum prior to such sale,
      it is not necessary in connection with the offer, sale and delivery of the
      Securities to the Initial Purchaser and to each Subsequent Purchaser in
      the manner contemplated by this Agreement and the Offering Memorandum to
      register the Securities under the 1933 Act or to qualify the Indenture
      under the Trust Indenture Act of 1939, as amended (the "1939 Act").

            (xxviii) Adviser Activities and Broker-Dealer Business. The Company
      is not required to register as an "investment adviser" or as a
      "broker-dealer" within the Investment Advisers Act of 1940, as amended
      (the "Advisers Act") or the 1934 Act, respectively, and the rules and
      regulations of the Commission promulgated thereunder. The Company is not
      required to be registered, licensed or qualified as an investment adviser
      or broker-dealer under the laws requiring any such registration, licensing
      or qualification in any jurisdiction in which it or its subsidiaries
      conduct business.

            Each of the subsidiaries has been duly registered as an investment
      adviser under the Advisers Act, and has been duly registered as a
      broker-dealer under the 1934 Act, and each such registration is in full
      force and effect, in each case to the extent such registration is required
      and with such exceptions as would not reasonably be expected to have a
      Material Adverse Effect. Each of the subsidiaries is duly registered,
      licensed or qualified as an investment adviser and broker-dealer under
      state and local laws where such registration, licensing or qualification
      is required by such laws and is in compliance with all such laws requiring
      any such registration, licensing or qualification, in each case with such
      exceptions, individually or in the aggregate, as would not reasonably be
      expected to have a Material Adverse Effect.

            (xxix) Compliance with Laws. Each of the subsidiaries which is
      required to be registered as an investment adviser or broker-dealer is and
      has been in compliance with all applicable laws and governmental rules and
      regulations, as may be applicable to its investment advisory or
      broker-dealer business, except to the extent that such non-compliance
      would not reasonably be expected to result in a Material Adverse Effect
      and none of such subsidiaries is prohibited by any provision of the
      Advisers Act or the 1940 Act from acting as an investment adviser. Each
      subsidiary of the Company which is required to be registered as a
      broker-dealer is a member in good standing of the National Association of
      Securities Dealers, Inc. No subsidiary which is required to be registered
      as an investment adviser or broker-dealer is in default with respect to
      any judgment,


                                       10
<PAGE>

      order, writ, injunction, decree, demand or assessment issued by any court
      or any foreign, federal, state, municipal or other governmental agency,
      board, commission, bureau, instrumentality or department, domestic or
      foreign, or by any self-regulatory authority relating to any aspect of its
      investment advisory or broker-dealer business, which would need to be
      disclosed pursuant to Rule 206(4)-4(b) under the Advisers Act, or which is
      reasonably likely to give rise to an affirmative answer to any of the
      questions in Item 11, Part 1 of the Form ADV of such registered investment
      adviser or which is reasonably likely to give rise to an affirmative
      answer to any of the questions in Item 7 of the Form BD of such
      broker-dealer.

            (xxx) Registration of Funds. Each mutual fund (the "Mutual Funds")
      has been since inception, is currently and will be immediately after
      consummation of the transactions contemplated herein, a duly registered
      investment company in compliance with the Investment Company Act of 1940,
      as amended (the "Investment Company Act"), and the rules and regulations
      promulgated thereunder and duly registered or licensed, except where any
      failure to be duly registered, individually or in the aggregate, would not
      reasonably be expected to result in a Material Adverse Effect. Since their
      initial offering, shares of each of the Mutual Funds have been duly
      qualified for sale under the securities laws of each jurisdiction in which
      they have been sold or offered for sale at such time or times during which
      such qualification was required, and, if not so qualified, the failure to
      so qualify would not reasonably be expected to have a Material Adverse
      Effect. The offering and sale of shares of each of the Mutual Funds have
      been registered under the 1933 Act during such period or periods for which
      such registration is required; the related registration statement has
      become effective under the 1933 Act; no stop order suspending the
      effectiveness of any such registration statement has been issued and no
      proceedings for that purpose have been instituted or, to the best
      knowledge of the Company, are contemplated. The registration statement of
      each Mutual Fund, together with the amendments and supplements thereto,
      under the Investment Company Act and the 1933 Act has, at all times when
      such registration statement was effective, complied in all material
      respects with the requirements of the Investment Company Act and the
      Securities Act then in effect and neither such registration statement nor
      any amendments or supplements thereto contained, at the time and in light
      of the circumstances in which they were made, an untrue statement of a
      material fact or omitted to state a material fact required to be stated
      therein or necessary to make the statements therein, at the time and in
      the light of the circumstances under which they were made, not misleading.
      All shares of each of the Mutual Funds were sold pursuant to an effective
      registration statement, or pursuant to a valid exemption from
      registration, and have been duly authorized and are validly issued, fully
      paid and non-assessable. Each of the Mutual Funds' investments has been
      made in accordance with its investment policies and restrictions set forth
      in its registration statement in effect at the time the investments were
      made and have been held in accordance with its respective investment
      policies and restrictions, to the extent applicable and in effect at the
      time such investments were held, except to the extent any failure to
      comply with such policies and restrictions, individually or in the
      aggregate, would not reasonably be expected to result in a Material
      Adverse Effect.


                                       11
<PAGE>

            (xxxi) Agreements. The Company is not party to any investment
      advisory agreement or distribution agreement and is not serving or acting
      as an investment adviser to any person. Each of the investment advisory
      agreements to which any of the subsidiaries is a party is a legal and
      valid obligation of such subsidiary and complies with the applicable
      requirements of the Advisers Act and the rules and regulations of the
      Commission thereunder. Each of the investment advisory agreements and
      distribution agreements between a subsidiary and a Mutual Fund is a legal
      and valid obligation of such subsidiary and complies with the applicable
      requirements of the Investment Company Act, and in the case of such
      distribution agreements, with the applicable requirements of the 1934 Act.
      No investment advisory agreement or distribution agreement to which any of
      the subsidiaries is a party that was either in effect on January 1, 2001
      or entered into by a subsidiary since January 1, 2001 has been terminated
      or expired, except where the failure to so comply or any such termination
      or expiration would not, individually or in the aggregate, reasonably be
      expected to have a Material Adverse Effect. None of such subsidiaries is
      in breach or violation of or in default under any such investment advisory
      agreement or distribution agreement, with such exceptions individually or
      in the aggregate as would not reasonably be expected to have a Material
      Adverse Effect. No subsidiary is serving or acting as an investment
      adviser to any person except pursuant to an agreement to which such
      subsidiary is a party and which is in full force and effect, other than
      any agreement the non-existence of which would not, individually or in the
      aggregate, reasonably be expected to have a Material Adverse Effect. The
      consummation of the transaction contemplated herein will not constitute an
      "assignment" as such term is defined in the Advisers Act and the 1934 Act.

      (b) Officer's Certificates. Any certificate signed by any officer of the
Company delivered to the Initial Purchaser or to counsel for the Initial
Purchaser shall be deemed a representation and warranty by the Company to the
Initial Purchaser as to the matters covered thereby.

      SECTION 2. Sale and Delivery to Initial Purchaser; Closing.

      (a) Initial Securities. On the basis of the representations and warranties
herein contained and subject to the terms and conditions herein set forth, the
Company agrees to sell to the Initial Purchaser, and the Initial Purchaser
agrees to purchase from the Company, at the price set forth in Schedule A,
$195,000,000 in aggregate principal amount at maturity of Initial Securities.

      (b) Option Securities. In addition, on the basis of the representations
and warranties herein contained and subject to the terms and conditions herein
set forth, the Company hereby grants an option to the Initial Purchaser to
purchase up to an additional $56,000,000 aggregate principal amount at maturity
of Securities at the same price per share set forth in Schedule A for the
Initial Securities, plus accreted original issue discount, if any, from the
Closing Time to the Date of Delivery (as defined below). The option hereby
granted will expire 30 days after the date hereof and may be exercised in whole
or in part from time to time only for the purpose of


                                       12
<PAGE>

covering over-allotments which may be made in connection with the offering and
distribution of the Initial Securities upon notice by the Initial Purchaser to
the Company setting forth the number of Option Securities as to which the
Initial Purchaser is then exercising the option and the time and date of payment
and delivery for such Option Securities. Any such time and date of delivery (a
"Date of Delivery") shall be determined by the Initial Purchaser, but shall not
be later than seven full business days after the exercise of said option, nor in
any event prior to the Closing Time, as hereinafter defined.

      (c) Payment. Payment of the purchase price for, and delivery of
certificates for, the Initial Securities shall be made at the offices of Sidley
Austin Brown & Wood LLP, One World Trade Center, New York, New York 10048, or at
such other place as shall be agreed upon by the Initial Purchaser and the
Company, at 10:00 A.M. (Eastern time) on the third (fourth, if the pricing
occurs after 4:30 P.M. (Eastern time) on any given day) business day after the
date hereof (unless postponed in accordance with the provisions of Section 10),
or such other time not later than ten business days after such date as shall be
agreed upon by the Initial Purchaser and the Company (such time and date of
payment and delivery being herein called "Closing Time").

      In addition, in the event that any or all of the Option Securities are
purchased by the Initial Purchaser, payment of the purchase price for, and
delivery of certificates for, such Option Securities shall be made at the
above-mentioned offices, or at such other place as shall be agreed upon by the
Initial Purchaser and the Company, on each Date of Delivery as specified in the
notice from the Initial Purchaser to the Company.

      Payment shall be made to the Company by wire transfer of immediately
available funds to a bank account designated by the Company, against delivery to
the Initial Purchaser of certificates for the Securities to be purchased by it.

      (d) Denominations; Registration. Certificates for the Initial Securities
and the Option Securities, if any, shall be in such denominations ($1,000 or
integral multiples thereof) and registered in such names as the Initial
Purchaser may request in writing at least one full business day before the
Closing Time or the relevant Date of Delivery, as the case may be. The
certificates for the Initial Securities and the Option Securities, if any, will
be made available for examination and packaging by the Initial Purchaser in The
City of New York not later than 10:00 A.M. (Eastern time) on the business day
prior to the Closing Time or the relevant Date of Delivery, as the case may be.

      (e) Qualification of Initial Purchaser. The Initial Purchaser hereby
represents and warrants to, and agrees with, the Company that the Initial
Purchaser (i) is a "qualified institutional buyer" within the meaning of Rule
144A under the 1933 Act (a "Qualified Institutional Buyer") and an "accredited
investor" within the meaning of Regulation D under the 1933 Act (an "Accredited
Investor"); (ii) has not and will not solicit offers for, or offer or sell the
Securities by any form of general solicitation or general advertising within the
meaning of Rule 502(c) under Regulation D under the 1933 Act; and (iii) will
otherwise act in accordance with the terms and conditions set forth in this
Agreement, including Section 6 hereof, and in the section


                                       13
<PAGE>

entitled "Transfer Restrictions" in the Offering Memorandum in connection with
the placement of the Securities contemplated hereby.

      SECTION 3. Covenants of the Company. The Company covenants with the
Initial Purchaser as follows:

      (a) Delivery of Offering Memorandum. The Company, as promptly as possible,
will furnish to the Initial Purchaser, without charge, such number of copies of
the Preliminary Offering Memorandum, the Final Offering Memorandum and any
amendments and supplements thereto and any documents incorporated by reference
therein as the Initial Purchaser may reasonably request.

      (b) Filings; Material Changes. The Company will immediately notify the
Initial Purchaser, and confirm such notice in writing, of (x) any filing made by
the Company of information relating to the offering of the Securities with any
securities exchange or any other regulatory body in the United States or any
other jurisdiction, and (y) prior to the completion of the placement of the
Securities by the Initial Purchaser as evidenced by a notice from the Initial
Purchaser to the Company, any material changes in or affecting the earnings,
business affairs or business prospects of the Company and its subsidiaries which
(i) make any statement in the Offering Memorandum false or misleading in any
material respect or (ii) if not disclosed in the Offering Memorandum, would
constitute a material omission therefrom. In such event, or if during such time
any event shall occur as a result of which it is necessary, in the reasonable
opinion of the Company, its counsel, the Initial Purchaser or counsel for the
Initial Purchaser, to amend or supplement the Final Offering Memorandum in order
that the Final Offering Memorandum not include any untrue statement of a
material fact or omit to state a material fact necessary in order to make the
statements therein not misleading in the light of the circumstances then
existing, the Company will forthwith amend or supplement the Final Offering
Memorandum by preparing and furnishing to the Initial Purchaser an amendment or
amendments of, or a supplement or supplements to, the Final Offering Memorandum
(in form and substance satisfactory in the reasonable opinion of counsel for the
Initial Purchaser) so that, as so amended or supplemented, the Final Offering
Memorandum will not include an untrue statement of a material fact or omit to
state a material fact necessary in order to make the statements therein, in the
light of the circumstances existing at the time it is delivered to a Subsequent
Purchaser, not misleading.

      (c) Amendments and Supplements. The Company will advise the Initial
Purchaser promptly of any proposal to amend or supplement the Offering
Memorandum, will furnish the Initial Purchaser with copies of such amendment or
supplement a reasonable amount of time prior thereto, and will not effect any
such amendment or supplement to which the Initial Purchaser shall reasonably
object. Neither the consent of the Initial Purchaser, nor the Initial
Purchaser's delivery of any such amendment or supplement, shall constitute a
waiver of any of the conditions set forth in Section 5 hereof.

      (d) Blue Sky Qualifications. The Company will use its reasonable efforts,
in


                                       14
<PAGE>

cooperation with the Initial Purchaser, to qualify the Securities and the shares
of Common Stock issuable upon conversion of Securities for offering and sale
under the applicable securities laws of such states and other jurisdictions
(domestic or foreign) as the Initial Purchaser may designate; provided, however,
that the Company shall not be obligated to file any general consent to service
of process or to qualify as a foreign corporation or as a dealer in securities
in any jurisdiction in which it is not so qualified or to subject itself to
taxation in respect of doing business in any jurisdiction in which it is not
otherwise so subject. In each jurisdiction in which the Securities or such
shares of Common Stock issuable upon conversion of the Securities have been so
qualified, the Company will file such statements and reports as may be required
by the laws of such jurisdiction to continue such qualification in effect for so
long as may be required in connection with the distribution of the Securities.

      (e) Use of Proceeds. The Company will use the net proceeds received by it
from the sale of the Securities in the manner indicated in the Offering
Memorandum under "Use of Proceeds."

      (f) Restriction on Sale of Common Stock. During a period of 60 days after
the date of the Offering Memorandum, the Company will not, without the prior
written consent of Merrill Lynch, (i) offer, pledge, sell, contract to sell,
sell any option or contract to purchase, purchase any option or contract to
sell, grant any option, right or warrant for the sale of, lend or otherwise
dispose of or transfer any shares of Common Stock or any securities convertible
into or exercisable or exchangeable for Common Stock or file any registration
statement under the 1933 Act with respect to any of the foregoing or (ii) enter
into any swap or any other agreement or any transaction that transfers, in whole
or in part, directly or indirectly, the economic consequence of ownership of the
Common Stock, whether any such swap or transaction described in clause (i) or
(ii) above is to be settled by delivery of Common Stock or such other
securities, in cash or otherwise. The foregoing sentence shall not apply to (A)
the Securities to be sold hereunder, (B) any shares of Common Stock issued by
the Company pursuant to existing options, employee benefit agreements or
incentive stock or director stock unit plans or (C) any shares of Common Stock
or such other securities issued as consideration for investments in or
acquisition of entities involved in the Adviser Activities or other financial
services related businesses made by the Company or any subsidiary of the
Company.

      (g) No Integration. The Company agrees that no future offer and sale of
debt securities of the Company of any class will be made if, as a result of the
doctrine of "integration" referred to in Rule 502 under the 1933 Act, such offer
and sale would render invalid (for the purpose of (i) the sale of the Securities
by the Company to the Initial Purchaser, (ii) the resale of the Securities by
the Initial Purchaser to Subsequent Purchasers, or (iii) the resale of the
Securities by such Subsequent Purchasers to others) the exemption from the
registration requirements of the 1933 Act provided by Section 4(2) thereof or by
Rule 144A.

      (h) Rule 144A Information. The Company agrees that, in order to render the
Securities eligible for resale pursuant to Rule 144A under the 1933 Act, while
any of the Securities are "restricted securities" within the meaning of the 1933
Act, to make available, upon


                                       15
<PAGE>

request, to any holder of Securities or prospective purchasers of Securities the
information specified in Rule 144A(d)(4), unless the Company furnishes
information to the Commission pursuant to Section 13 or 15(d) of the 1934 Act.

      (i) No Purchases. Until the expiration of two years after the original
issuance of the Securities, the Company will not (directly or through a
subsidiary), and will use its reasonable efforts to cause its "affiliates" (as
such term is defined in Rule 144(a)(1) under the 1933 Act) not to, purchase or
agree to purchase or otherwise acquire any Securities which are "restricted
securities" (as such term is defined under Rule 144(a)(3) under the 1933 Act),
whether as beneficial owner or otherwise (except as agent on behalf of and for
the account of customers in the ordinary course of business as a securities
broker in unsolicited broker's transactions) unless, immediately upon any such
purchase, the Company or any such affiliate shall submit such Securities to the
Trustee for cancellation.

      (j) PORTAL. The Company will use its reasonable efforts to permit the
Securities to be designated as PORTAL securities in accordance with the rules
and regulations adopted by the National Association of Securities Dealers, Inc.
relating to the PORTAL Market.

      (k) Reasonable Inquiries; Information. In connection with the original
distribution of the Securities, the Company agrees that, prior to any offer or
resale of the Securities by the Initial Purchaser, the Initial Purchaser and
counsel for the Initial Purchaser shall have the right to make reasonable
inquiries into the business of the Company and its subsidiaries. The Company
also agrees to provide each prospective Subsequent Purchaser of Securities who
so requests information of the type specified in Rule 502(b)(2)(v) under the
1933 Act.

      (l) Registration Rights Agreement; Trust Indenture Act. The Company agrees
that it will comply with all the terms and conditions of the Registration Rights
Agreement, and that prior to any registration of the Securities pursuant to the
Registration Rights Agreement, or at such earlier time as may be required by
applicable law, that it will cause the Indenture to be qualified under the Trust
Indenture Act of 1939.

      SECTION 4. Payment of Expenses.

      (a) Expenses. The Company will pay all expenses incident to the
performance of its obligations under this Agreement, including (i) the printing
of the Preliminary Offering Memorandum, the Final Offering Memorandum and of
each amendment or supplement thereto, (ii) the printing or reproduction of this
Agreement and the Indenture and relating documents, (iii) the preparation,
issuance and delivery of the certificates for the Securities to the Initial
Purchaser, (iv) the fees and disbursements of the Company's counsel and
accountants, (v) the qualification of the Securities and the shares of Common
Stock issuable upon conversion of the Securities under securities laws in
accordance with the provisions of Section 3(d), including filing fees and the
fees and disbursements of counsel for the Initial Purchaser in connection
therewith and in connection with the preparation of the Blue Sky Survey, (vi)
any fees of the National Association of Securities Dealers, Inc., (vii) the fees
and expenses of the Trustee, including the fees and disbursements of counsel for
the Trustee in connection with the Indenture, and (viii) any fees


                                       16
<PAGE>

payable in connection with the rating of the Securities.

      (b) Termination of Agreement. If this Agreement is terminated by the
Initial Purchaser in accordance with the provisions of Section 5 or Section
9(a)(i) hereof, the Company shall reimburse the Initial Purchaser for all of its
out-of-pocket expenses, including the reasonable fees and disbursements of
counsel for the Initial Purchaser.

      SECTION 5. Conditions of Initial Purchaser's Obligations. The obligation
of the Initial Purchaser to purchase the Securities hereunder is subject to the
accuracy of the representations and warranties of the Company contained in
Section 1 hereof or in certificates of any officer of the Company delivered
pursuant to the provisions hereof, to the performance by the Company of its
covenants and other obligations hereunder, and to the following further
conditions:

      (a) Opinion of Counsel for Company. At the Closing Time, the Initial
Purchaser shall have received the favorable opinion, dated as of Closing Time,
of Goodwin Procter LLP, counsel for the Company, in form and substance
satisfactory to the Initial Purchaser and counsel for the Initial Purchaser. In
giving such opinion such counsel may rely, as to all matters governed by the
laws of jurisdictions other than the law of the Commonwealth of Massachusetts,
the federal law of the United States and the General Corporation Law of the
State of Delaware, upon the opinions of counsel satisfactory to the Initial
Purchaser. Such counsel may also state that, insofar as such opinion involves
factual matters, they have relied, to the extent they deem proper, upon
certificates of the officers of the Company and certificates of public
officials.

      (b) Opinion of Counsel for Initial Purchaser. At the Closing Time, the
Initial Purchaser shall have received the favorable opinion, satisfactory to the
Initial Purchaser, dated as of Closing Time, of Sidley Austin Brown & Wood LLP,
counsel for the Initial Purchaser. In giving such opinion such counsel may rely,
as to all matters governed by the laws of jurisdictions other than the law of
the State of New York, the federal law of the United States and the General
Corporation Law of the State of Delaware, upon the opinions of counsel
satisfactory to the Initial Purchaser. Such counsel may also state that, insofar
as such opinion involves factual matters, they have relied, to the extent they
deem proper, upon certificates of officers of the Company and certificates of
public officials.

      (c) Officers' Certificate. At the Closing Time, there shall not have been,
since the date hereof or since the respective dates as of which information is
given in the Offering Memorandum, any material adverse change or prospective
material adverse change in the business, management, financial position,
stockholders' equity or results of operations of the Company and its
subsidiaries considered as one enterprise, whether or not arising in the
ordinary course of business, and the Initial Purchaser shall have received a
certificate of the President or a Vice President of the Company and of the chief
financial or chief accounting officer of the Company, dated as of Closing Time,
to the effect that (i) there has been no such material adverse change, (ii) the
representations and warranties in Section 1(a) hereof are true and correct with
the same force and effect as though expressly made at and as of Closing Time,
and (iii) the Company has complied with all of the agreements entered into in
connection with the transaction


                                       17
<PAGE>

contemplated herein and satisfied all conditions on its part to be performed or
satisfied at or prior to Closing Time.

      (d) Accountant's Comfort Letter. At the time of the execution of this
Agreement, the Initial Purchaser shall have received from PricewaterhouseCoopers
LLP a letter dated such date, in form and substance satisfactory to the Initial
Purchaser, containing statements and information of the type ordinarily included
in accountants' "comfort letters" to initial purchasers with respect to the
financial statements and certain financial information contained in the Offering
Memorandum.

      (e) Bring-down Comfort Letter. At the Closing Time, the Initial Purchaser
shall have received from PricewaterhouseCoopers LLP a letter, dated as of
Closing Time, to the effect that they reaffirm the statements made in the letter
furnished pursuant to subsection (d) of this Section, except that the specified
date referred to shall be a date not more than three business days prior to the
Closing Time.

      (f) PORTAL Market. At the Closing Time, the Securities and the Common
Stock issuable upon conversion of the Securities shall have been designated
PORTAL eligible securities in accordance with the rules and regulations of the
National Association of Securities Dealers, Inc., subject to official notice of
issuance.

      (g) Maintenance of Rating. At the Closing Time, the Securities shall be
rated at least BBB- by Standard & Poor's Ratings Services, a division of The
McGraw-Hill Companies, Inc. and the Company shall have delivered to the Initial
Purchaser a letter dated the Closing Time, from such rating agency, or other
evidence satisfactory to the Initial Purchaser, confirming that the Securities
have such rating; and since the date of this Agreement, there shall not have
occurred a downgrading in the rating assigned to the Securities or any of the
Company's other debt securities by any "nationally recognized statistical rating
agency," as that term is defined by the Commission for purposes of Rule
436(g)(2) under the 1933 Act, and no such organization shall have publicly
announced that it has under surveillance or review its rating of the Securities
or any of the Company's other debt securities.

      (h) Lock-up Agreements. At the date of this Agreement, the Initial
Purchaser shall have received an agreement substantially in the form of Exhibit
A hereto signed by the persons listed on Schedule B hereto.

      (i) Indenture and Registration Rights Agreement. At or prior to the
Closing Time, the Company and the Trustee shall have executed and delivered the
Indenture and the Company and the Initial Purchaser shall have executed and
delivered the Registration Rights Agreement.

      (j) Conditions to Purchase of Option Securities. In the event that the
Initial Purchaser exercises its option provided in Section 2(b) hereof to
purchase all or any portion of the Option Securities, the representations and
warranties of the Company contained herein and the statements in any
certificates furnished by the Company or any subsidiary of the Company hereunder
shall be true and correct as of each Date of


                                       18
<PAGE>

Delivery and, at the relevant Date of Delivery, the Initial Purchaser shall have
received:

            (i) Officers' Certificate. A certificate, dated such Date of
      Delivery, of the President or a Vice President of the Company and of the
      chief financial or chief accounting officer of the Company confirming that
      the certificate delivered at the Closing Time pursuant to Section 5(c)
      hereof remains true and correct as of such Date of Delivery.

            (ii) Opinion of Counsel for Company. The favorable opinion of
      Goodwin Procter LLP, counsel for the Company, dated such Date of Delivery,
      relating to the Option Securities to be purchased on such Date of Delivery
      and otherwise to the same effect as the opinion required by Section 5(a)
      hereof.

            (iii) Opinion of Counsel for Initial Purchaser. The favorable
      opinion of Sidley Austin Brown & Wood LLP, counsel for the Initial
      Purchaser, dated such Date of Delivery, relating to the Option Securities
      to be purchased on such Date of Delivery and otherwise to the same effect
      as the opinion required by Section 5(b) hereof.

            (iv) Bring-down Comfort Letter. A letter from PricewaterhouseCoopers
      LLP, dated such Date of Delivery, substantially in the same form and
      substance as the letter furnished to the Initial Purchaser pursuant to
      Section 5(e) hereof, except that the "specified date" in the letter
      furnished pursuant to this paragraph shall be a date not more than five
      days prior to such Date of Delivery.

            (v) No Downgrading. Subsequent to the date of this Agreement, no
      downgrading shall have occurred in the rating accorded the Securities or
      of any of the Company's other securities by any "nationally recognized
      statistical rating organization", as that term is defined by the
      Commission for purposes of Rule 436(g)(2) under the 1933 Act, and no such
      organization shall have publicly announced that it has under surveillance
      or review its ratings of any of the Company's securities.

      (k) Additional Documents. At Closing Time and at each Date of Delivery,
counsel for the Initial Purchaser shall have been furnished with such documents
and opinions as they may reasonably require for the purpose of enabling them to
pass upon the issuance and sale of the Securities as herein contemplated, or in
order to evidence the accuracy of any of the representations or warranties, or
the fulfillment of any of the conditions, herein contained; and all proceedings
taken by the Company in connection with the issuance and sale of the Securities
as herein contemplated shall be satisfactory in form and substance in the
reasonable judgment of the Initial Purchaser and counsel for the Initial
Purchaser.

      (l) Termination of Agreement. If any condition specified in this Section
shall not have been fulfilled when and as required to be fulfilled, this
Agreement, or, in the case of any condition to the purchase of Option
Securities, on a Date of Delivery which is after the Closing Time, the
obligations of the Initial Purchaser to purchase the relevant Option Securities,
may be terminated by the Initial Purchaser by notice to the Company at any time
at or prior to Closing


                                       19
<PAGE>

Time or such Date of Delivery, as the case may be, and such termination shall be
without liability of any party to any other party except as provided in Section
4 and except that Sections 7 and 8 shall survive any such termination and remain
in full force and effect.

      SECTION 6. Subsequent Offers and Resales of the Securities.

      (a) Each of the Initial Purchaser and the Company, as the case may be,
hereby establish and agree to observe the following procedures in connection
with the offer and sale by the Initial Purchaser of the Securities.

            (i) Offers and sales of the Securities will be made by the Initial
      Purchaser only to institutional investors that are reasonably believed to
      qualify as Qualified Institutional Buyers.

            (ii) The Securities will be offered by the Initial Purchaser only by
      approaching prospective Subsequent Purchasers on an individual basis. No
      general solicitation or general advertising (within the meaning of Rule
      502(c) under the 1933 Act) will be used in connection with the offering of
      the Securities.

            (iii) In the case of a Subsequent Purchaser of a Security acting as
      a fiduciary for one or more third parties, in connection with an offer and
      sale to such purchaser pursuant to clause (i) above, each third party
      shall, in the judgment of the Initial Purchaser, be a Qualified
      Institutional Buyer.

            (iv) Until the completion of the placement of the Securities by the
      Initial Purchaser, the transfer restrictions and the other provisions set
      forth in Section 2.12 of the Indenture, including the legend required
      thereby, shall apply to the Securities except as otherwise agreed by the
      Company and the Initial Purchaser. Following the sale of the Securities by
      the Initial Purchaser to each Subsequent Purchaser pursuant to the terms
      hereof, the Initial Purchaser shall not be liable or responsible to the
      Company for any losses, damages or liabilities suffered or incurred by the
      Company, including any losses, damages or liabilities under the 1933 Act,
      arising from or relating to any subsequent resale or transfer of any
      Security, except to the extent caused by failure to deliver an amended or
      supplemented Offering Memorandum.

            (v) The Initial Purchaser will deliver at or prior to sale to each
      purchaser of the Securities from such Initial Purchaser, in connection
      with its original distribution of the Securities, a copy of the Final
      Offering Memorandum, as amended and supplemented at the date of such
      delivery.

            (vi) In connection with the original distribution of the Securities,
      the Company agrees that, prior to any offer or resale of the Securities by
      the Initial Purchaser, the Initial Purchaser and counsel for the Initial
      Purchaser shall have the right to make reasonable inquiries into the
      business of the Company and its subsidiaries.


                                       20
<PAGE>

            (vii) The Initial Purchaser will promptly notify the Company in
      writing of the completion of the placement of the Securities by it.

      SECTION 7. Indemnification.

      (a) Indemnification of Initial Purchaser. The Company agrees to indemnify
and hold harmless the Initial Purchaser and each person, if any, who controls
the Initial Purchaser within the meaning of Section 15 of the 1933 Act or
Section 20 of the 1934 Act to the extent and in the manner set forth in clauses
(i), (ii) and (iii) below.

            (i) against any and all loss, liability, claim, damage and expense
      whatsoever, as incurred, resulting from any untrue statement or alleged
      untrue statement of a material fact contained in any Preliminary Offering
      Memorandum or the Final Offering Memorandum (or any amendment or
      supplement thereto), or the omission or alleged omission therefrom of a
      material fact necessary in order to make the statements therein, in the
      light of the circumstances under which they were made, not misleading;

            (ii) against any and all loss, liability, claim, damage and expense
      whatsoever, as incurred, to the extent of the aggregate amount paid in
      settlement of any litigation, or any investigation or proceeding by any
      governmental agency or body, commenced or threatened, or of any claim
      whatsoever based upon any such untrue statement or omission, or any such
      alleged untrue statement or omission; provided that (subject to Section
      7(d) below) any such settlement is effected with the written consent of
      the Company; and

            (iii) against any and all expense whatsoever, as incurred (including
      the reasonable fees and disbursements of counsel chosen by the Initial
      Purchaser), reasonably incurred in investigating, preparing or defending
      against any litigation, or any investigation or proceeding by any
      governmental agency or body, commenced or threatened, or any claim
      whatsoever based upon any such untrue statement or omission, or any such
      alleged untrue statement or omission, to the extent that any such expense
      is not paid under (i) or (ii) above;

provided, however, that this indemnity agreement shall not apply to (i) any
loss, liability, claim, damage or expense to the extent arising out of any
untrue statement or omission or alleged untrue statement or omission made in
reliance upon and in conformity with written information furnished to the
Company by the Initial Purchaser expressly for use in the Offering Memorandum
(or any amendment or supplement thereto) and (ii) any loss, liability, claim,
damage or expense to the extent arising out of any untrue statement or omission
or alleged untrue statement or omission in the Preliminary Offering Memorandum
that is correct in the Final Offering Memorandum if the person asserting any
such loss, liability, claim, damage or expense purchased any of the Securities
from the Initial Purchaser but was not sent or given a copy of the Final
Offering Memorandum, at or prior to the written confirmation of the sale of such
Securities to such person unless (A) the Company has not complied with Section
3(a) of this Agreement and (B) any such untrue statement or omission or alleged
untrue statement or omission in the


                                       21
<PAGE>

Preliminary Offering Memorandum has not been corrected in the Final Offering
Memorandum.

      (b) Indemnification of Company, Directors and Officers. The Initial
Purchaser agrees to indemnify and hold harmless the Company, its directors, its
officers and each person, if any, who controls the Company within the meaning of
Section 15 of the 1933 Act or Section 20 of the 1934 Act against any and all
loss, liability, claim, damage and expense described in the indemnity contained
in subsection (a) of this Section, as incurred, but only with respect to untrue
statements or omissions, or alleged untrue statements or omissions, made in the
Offering Memorandum (or any amendment or supplement thereto) in reliance upon
and in conformity with written information furnished to the Company by the
Initial Purchaser expressly for use in the Offering Memorandum (or any amendment
or supplement thereto).

      (c) Actions against Parties; Notification. Each indemnified party shall
give notice as promptly as reasonably practicable to each indemnifying party of
any action commenced against it in respect of which indemnity may be sought
hereunder, but failure to so notify an indemnifying party shall not relieve such
indemnifying party from any liability hereunder to the extent it is not
materially prejudiced as a result thereof and in any event shall not relieve it
from any liability which it may have otherwise than on account of this indemnity
agreement. In the case of parties indemnified pursuant to Section 7(a) above,
counsel to the indemnified parties shall be selected by Merrill Lynch, and, in
the case of parties indemnified pursuant to Section 7(b) above, counsel to the
indemnified parties shall be selected by the Company. An indemnifying party may
participate at its own expense in the defense of any such action; provided,
however, that counsel to the indemnifying party shall not (except with the
consent of the indemnified party) also be counsel to the indemnified party. In
no event shall the indemnifying parties be liable for fees and expenses of more
than one counsel (in addition to any local counsel) separate from their own
counsel for all indemnified parties in connection with any one action or
separate but similar or related actions in the same jurisdiction arising out of
the same general allegations or circumstances. No indemnifying party shall,
without the prior written consent of the indemnified parties, settle or
compromise or consent to the entry of any judgment with respect to any
litigation, or any investigation or proceeding by any governmental agency or
body, commenced or threatened, or any claim whatsoever in respect of which
indemnification or contribution could be sought under this Section 7 or Section
8 hereof (whether or not the indemnified parties are actual or potential parties
thereto), unless such settlement, compromise or consent (i) includes an
unconditional release of each indemnified party from all liability arising out
of such litigation, investigation, proceeding or claim and (ii) does not include
a statement as to or an admission of fault, culpability or a failure to act by
or on behalf of any indemnified party.

      (d) Settlement without Consent if Failure to Reimburse. If at any time an
indemnified party shall have requested an indemnifying party to reimburse the
indemnified party for fees and expenses of counsel, such indemnifying party
agrees that it shall be liable for any settlement of the nature contemplated by
Section 7(a)(ii) effected without its written consent if (i) such settlement is
entered into more than 45 days after receipt by such indemnifying party of the
aforesaid request, (ii) such indemnifying party shall have received notice of
the terms of such


                                       22
<PAGE>

settlement at least 30 days prior to such settlement being entered into, and
(iii) such indemnifying party shall not have reimbursed such indemnified party
in accordance with such request prior to the date of such settlement.
Notwithstanding the immediately preceding sentence, if at any time an
indemnified party shall have requested an indemnifying party to reimburse the
indemnified party for fees and expenses of counsel, an indemnifying party shall
not be liable for any settlement of the nature contemplated by Section 7(a)(ii)
effected without its consent if such indemnifying party (i) reimburses such
indemnified party in accordance with such request to the extent it considers
such request to be reasonable and (ii) provides written notice to the
indemnified party substantiating the unpaid balance as unreasonable, in each
case prior to the date of such settlement.

      SECTION 8. Contribution. If the indemnification provided for in Section 7
hereof is for any reason unavailable to or insufficient to hold harmless an
indemnified party in respect of any losses, liabilities, claims, damages or
expenses referred to therein, then each indemnifying party shall contribute to
the aggregate amount of such losses, liabilities, claims, damages and expenses
incurred by such indemnified party, as incurred, (i) in such proportion as is
appropriate to reflect the relative benefits received by the Company on the one
hand and the Initial Purchaser on the other hand from the offering of the
Securities pursuant to this Agreement or (ii) if the allocation provided by
clause (i) is not permitted by applicable law, in such proportion as is
appropriate to reflect not only the relative benefits referred to in clause (i)
above but also the relative fault of the Company on the one hand and of the
Initial Purchaser on the other hand in connection with the statements or
omissions which resulted in such losses, liabilities, claims, damages or
expenses, as well as any other relevant equitable considerations.

      The relative benefits received by the Company on the one hand and the
Initial Purchaser on the other hand in connection with the offering of the
Securities pursuant to this Agreement shall be deemed to be in the same
respective proportions as the total net proceeds from the offering of the
Securities pursuant to this Agreement (before deducting expenses) received by
the Company and the total purchase discount received by the Initial Purchaser,
in each case as set forth in the Offering Memorandum, bear to the aggregate
initial public offering price of the Securities as set forth on such cover.

      The relative fault of the Company on the one hand and the Initial
Purchaser on the other hand shall be determined by reference to, among other
things, whether any such untrue or alleged untrue statement of a material fact
or omission or alleged omission to state a material fact relates to information
supplied by the Company or by the Initial Purchaser and the parties' relative
intent, knowledge, access to information and opportunity to correct or prevent
such statement or omission.

      The Company and the Initial Purchaser agree that it would not be just and
equitable if contribution pursuant to this Section 8 were determined by pro rata
allocation or by any other method of allocation which does not take account of
the equitable considerations referred to above in this Section 8. The aggregate
amount of losses, liabilities, claims, damages and expenses incurred by an
indemnified party and referred to above in this Section 8 shall be


                                       23
<PAGE>

deemed to include any legal or other expenses reasonably incurred by such
indemnified party in investigating, preparing or defending against any
litigation, or any investigation or proceeding by any governmental agency or
body, commenced or threatened, or any claim whatsoever based upon any such
untrue or alleged untrue statement or omission or alleged omission.

      Notwithstanding the provisions of this Section 8, the Initial Purchaser
shall not be required to contribute any amount in excess of the amount by which
the total price at which the Securities underwritten by it and distributed to
the public were offered to the public exceeds the amount of any damages which
the Initial Purchaser has otherwise been required to pay by reason of any such
untrue or alleged untrue statement or omission or alleged omission.

      No person guilty of fraudulent misrepresentation (within the meaning of
Section 11(f) of the 1933 Act) shall be entitled to contribution from any person
who was not guilty of such fraudulent misrepresentation.

      For purposes of this Section 8, each person, if any, who controls the
Initial Purchaser within the meaning of Section 15 of the 1933 Act or Section 20
of the 1934 Act shall have the same rights to contribution as the Initial
Purchaser, and each director of the Company, each officer of the Company, and
each person, if any, who controls the Company within the meaning of Section 15
of the 1933 Act or Section 20 of the 1934 Act shall have the same rights to
contribution as the Company.

      SECTION 9. Termination of Agreement.

      (a) Termination; General. The Initial Purchaser may terminate this
Agreement, by notice to the Company, at any time at or prior to Closing Time (i)
if there has been, since the time of execution of this Agreement or since the
respective dates as of which information is given in the Offering Memorandum,
any material adverse change or prospective material adverse change in the
business, management, financial position, stockholders' equity or results of
operations of the Company and its subsidiaries considered as one enterprise,
whether or not arising in the ordinary course of business, or (ii) if there has
occurred any material adverse change in the financial markets in the United
States, any outbreak of hostilities or escalation thereof or other calamity or
crisis or any change or development involving a prospective change in national
or international political, financial or economic conditions, in each case the
effect of which is such as to make it, in the judgment of the Initial Purchaser,
impracticable to market the Securities or to enforce contracts for the sale of
the Securities, or (iii) if trading in any securities of the Company has been
suspended or materially limited by the Commission or the New York Stock Exchange
or if trading generally on the New York Stock Exchange or the American Stock
Exchange or in the Nasdaq National Market has been suspended or materially
limited, or minimum or maximum prices for trading have been fixed, or maximum
ranges for prices have been required, by any of said exchanges or by such system
or by order of the Commission, the National Association of Securities Dealers,
Inc. or any other governmental authority, or (iv) if a banking moratorium has
been declared by either federal or New York authorities.

      (b) Liabilities. If this Agreement is terminated pursuant to this Section,
such


                                       24
<PAGE>

termination shall be without liability of any party to any other party except as
provided in Section 4 hereof, and provided further that Sections 7 and 8 shall
survive such termination and remain in full force and effect.

      SECTION 10. Notices. All notices and other communications hereunder shall
be in writing and shall be deemed to have been duly given if mailed or
transmitted by any standard form of telecommunication. Notices to the Initial
Purchaser shall be directed to Merrill Lynch at North Tower, World Financial
Center, New York, New York 10281-1209, attention of Paul A. Pepe, Managing
Director; and notices to the Company shall be directed to it at Two
International Place, Boston, MA 02110, attention of Treasurer.

      SECTION 11. Parties. This Agreement shall inure to the benefit of and be
binding upon each of the Initial Purchaser and the Company and their respective
successors. Nothing expressed or mentioned in this Agreement is intended or
shall be construed to give any person, firm or corporation, other than the
Initial Purchaser and the Company and their respective successors and the
controlling persons and officers and directors referred to in Sections 7 and 8
and their heirs and legal representatives, any legal or equitable right, remedy
or claim under or in respect of this Agreement or any provision herein
contained. This Agreement and all conditions and provisions hereof are intended
to be for the sole and exclusive benefit of the Initial Purchaser and the
Company and their respective successors, and said controlling persons and
officers and directors and their heirs and legal representatives, and for the
benefit of no other person, firm or corporation. No purchaser of Securities from
the Initial Purchaser shall be deemed to be a successor by reason merely of such
purchase.

      SECTION 12. GOVERNING LAW AND TIME. THIS AGREEMENT SHALL BE GOVERNED BY
AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK. EXCEPT AS
OTHERWISE SET FORTH HEREIN, SPECIFIED TIMES OF DAY REFER TO NEW YORK CITY TIME.

      SECTION 13. Effect of Headings. The Article and Section headings herein
and the Table of Contents are for convenience only and shall not affect the
construction hereof.

                            [Signature page follows]


                                       25
<PAGE>

      If the foregoing is in accordance with your understanding of our
agreement, please sign and return to the Company a counterpart hereof, whereupon
this instrument, along with all counterparts, will become a binding agreement
between the Initial Purchaser and the Company in accordance with its terms.

                                            Very truly yours,

                                            AFFILIATED MANAGERS GROUP, INC.

                                            By:    /s/ Darrell W. Crate
                                                   ----------------------------
                                            Name:  Darrell W. Crate
                                            Title: Sr. Vice President and
                                                   Chief Financial Officer

CONFIRMED AND ACCEPTED,
  as of the date first above written:

MERRILL LYNCH & CO.
MERRILL LYNCH, PIERCE, FENNER & SMITH
                  INCORPORATED

By: /s/ Robert Aberman
    --------------------------
       Authorized Signatory


                                       26
<PAGE>

                                   SCHEDULE A

                         AFFILIATED MANAGERS GROUP, INC.

                     $195,000,000 Liquid Yield Option Notes

      1. The initial public offering price per $1,000 principal amount at
maturity of the Securities shall be $904.95, which represents a yield to
maturity of 0.50% per annum (computed on a semiannual bond equivalent basis).

      2. The purchase price to be paid by the Initial Purchaser per $1,000
principal amount at maturity of the Securities shall be $882.33.

      3. The Securities shall be convertible into shares of common stock, par
value $0.01 per share, of the Company at an initial conversion price of
approximately $77.88 per share (equivalent to a conversion rate of 11.6195
shares per $1,000 principal amount of Securities).

      4. Prior to May 7, 2006, the LYONs will not be redeemable at the Company's
option. Beginning on May 7, 2006, the Company may redeem the LYONs for cash as a
whole at any time, or from time to time in part, at the redemption prices set
forth below. Such prices reflect the accrued original issue discount calculated
to each such date. The redemption price of a LYON redeemed between such dates
would include an additional amount reflecting the additional original issue
discount accrued since the next preceding date in the table.

<TABLE>
<CAPTION>
                                                                   (2)
                                                    (1)          ORIGINAL           (3)
                                                    LYON          ISSUE          REDEMPTION
                                                   ISSUE         DISCOUNT          PRICE
               REDEMPTION DATE                     PRICE         AT .50%         (1) + (2)
               ---------------                     -----         -------         ---------
<S>                                               <C>             <C>            <C>
May 7, 2006.................................      $904.95         $22.88           $927.83
May 7, 2007.................................       904.95          27.52            932.47
May 7, 2008.................................       904.95          32.19            937.14
May 7, 2009.................................       904.95          36.88            941.83
May 7, 2010.................................       904.95          41.60            946.55
May 7, 2011.................................       904.95          46.34            951.29
May 7, 2012.................................       904.95          51.10            956.05
May 7, 2013.................................       904.95          55.89            960.84
May 7, 2014.................................       904.95          60.70            965.65
May 7, 2015.................................       904.95          65.53            970.48
May 7, 2016.................................       904.95          70.39            975.34
May 7, 2017.................................       904.95          75.27            980.22
May 7, 2018.................................       904.95          80.18            985.13
</TABLE>


                                      A-1
<PAGE>

<TABLE>
<CAPTION>
                                                                   (2)
                                                    (1)          ORIGINAL           (3)
                                                    LYON          ISSUE          REDEMPTION
                                                   ISSUE         DISCOUNT          PRICE
               REDEMPTION DATE                     PRICE         AT .50%         (1) + (2)
               ---------------                     -----         -------         ---------
<S>                                               <C>             <C>            <C>
May 7, 2019.................................       904.95          85.11            990.06
May 7, 2020.................................       904.95          90.07            995.02
At stated maturity..........................      $904.95         $95.05         $1,000.00
</TABLE>

      If converted to semiannual coupon LYONs following the occurrence of a Tax
Event, the LYONs will be redeemable at the restated principal amount plus
accrued and unpaid interest from the date of the conversion through the
redemption date.

      5. On the purchase dates of May 7, 2002, May 7, 2004, May 7, 2006, May 7,
2011 and May 7, 2016, the Company will, at the option of the holder, be required
to purchase any outstanding LYON for which a written purchase notice has been
properly delivered by the holder and not withdrawn, subject to certain
additional conditions. The purchase price of a LYON will be as follows:

      o     $909.48 per LYON on May 7, 2002;

      o     $918.61 per LYON on May 7, 2004;

      o     $927.83 per LYON on May 7, 2006;

      o     $951.29 per LYON on May 7, 2011; and

      o     $975.34 per LYON on May 7, 2016.

      The Company may, at its option, elect to pay the purchase price in cash or
shares of common stock, or any combination thereof.

      If prior to a purchase date the LYONs have been converted to semiannual
coupon LYONs following the occurrence of a Tax Event, the purchase price will be
equal to the restated principal amount plus accrued and unpaid interest from the
date of the conversion to the purchase date.

      6. In the event of any Change in Control occurring on or prior to May 7,
2006, each holder will have the right, at the holder's option, subject to the
terms and conditions of the indenture, to require the Company to purchase all or
any portion of the holder's LYONs at a cash price equal to the issue price plus
accrued original issue discount to the change in control purchase date.

      If prior to a change in control purchase date the LYONs have been
converted to


                                      A-2
<PAGE>

semiannual coupon LYONs following the occurrence of a Tax Event, the Company
will be required to purchase the LYONs at a cash price equal to the restated
principal amount plus accrued and unpaid interest from the date of the
conversion to the change in control purchase date.

      7. From and after the date of the occurrence of a Tax Event (as defined in
the Offering Memorandum), the Company shall have the option to elect to have
interest in lieu of future original issue discount accrue at 0.50% per year on a
principal amount per LYON (the "restated principal amount") equal to the issue
price plus original issue discount accrued to the date of the Tax Event or the
date on which the Company exercises the option described herein, whichever is
later (the "option exercise date").

      Such interest shall accrue from the option exercise date and shall be
payable semiannually on the interest payment dates of May 7 and November 7 of
each year to holders of record at the close of business on April 21 or October
22 immediately preceding the interest payment date. Interest will be computed on
the basis of a 360-day year comprised of twelve 30-day months. Interest will
accrue from the most recent date to which interest has been paid or, if no
interest has been paid, from the option exercise date.


                                      A-3
<PAGE>

                                   SCHEDULE B

                          List of persons and entities
                               subject to lock-up

<TABLE>
<S>                            <C>
William J. Nutt........................................Chairman and Chief Executive Officer

Sean M. Healey........................................President and Chief Operating Officer

Seth W. Brennan......................................Senior Vice President, New Investments

Darrell W. Crate...............Senior Vice President, Chief Financial Officer and Treasurer

Nathaniel Dalton.......................Senior Vice President, General Counsel and Secretary

Richard E. Floor...................................................................Director

Stephen J. Lockwood................................................................Director

Harold J. Meyerman.................................................................Director

Dr. Rita M. Rodriguez..............................................................Director

William F. Weld....................................................................Director
</TABLE>


                                      B-1
<PAGE>

                                                                       Exhibit A

                   [Form of lock-up pursuant to Section 5(h)]

                                                            May 7, 2001

MERRILL LYNCH & CO.
Merrill Lynch, Pierce, Fenner & Smith
                      Incorporated
North Tower
Word Financial Center
New York, New York  10281-1209

                Re:   Proposed Offering of Liquid Yield Option
                      Notes by Affiliated Mangers Group, Inc.

Dear Sirs:

      The undersigned, a stockholder [and an officer and/or director] of
Affiliated Managers Group, Inc., a Delaware corporation (the "Company"),
understands that Merrill Lynch & Co., Merrill Lynch, Pierce, Fenner & Smith
Incorporated ("Merrill Lynch") proposes to enter into a Purchase Agreement (the
"Purchase Agreement') with the Company providing for the offering of
$195,000,000 aggregate principal amount of the Company's Liquid Yield Option
Notes due May (Zero Coupon - Senior) (the "Securities"). In recognition of the
benefit that such an offering will confer upon the undersigned as a stockholder
[and an officer and/or director] of the Company, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
undersigned agrees with Merrill Lynch that, during a period of 60 days from the
date of the final offering memorandum relating to the offer and sale of the
Securities, the undersigned will not, without the prior written consent of
Merrill Lynch, directly or indirectly, (i) offer, pledge, sell, contract to
sell, sell any option or contract to purchase, purchase any option or contract
to sell, grant any option, right or warrant for the sale of, lend or otherwise
dispose of or transfer any shares of the Company's Common Stock, par value $.01
per share (the "Common Stock"), or any securities convertible into or
exchangeable or exercisable for or repayable with Common Stock, whether now
owned or hereafter acquired by the undersigned or with respect to which the
undersigned has or hereafter acquires the power of disposition, or file any
registration statement under the Securities Act of 1933, as amended, with
respect to any of the foregoing or (ii) enter



                                     Ex. A-1
<PAGE>

into any swap or any other agreement or any transaction that transfers, in whole
or in part, directly or indirectly, the economic consequence of ownership of
Common Stock or any securities convertible into or exchangeable for Common
Stock, whether any such swap or transaction is to be settled by delivery of
Common Stock or other securities, in cash or otherwise.

                                            Very truly yours,

                                            Signature:  ____________________

                                            Print Name:_____________________


                                    Ex. A-2