FILED PURSUANT TO RULE 424(b)(3) AND (c)
                                                           FILE NUMBER 333-62180

                             PROSPECTUS SUPPLEMENT
                      (TO PROSPECTUS DATED JUNE 18, 2001)

                                  $251,000,000
                        AFFILIATED MANAGERS GROUP, INC.
                     LIQUID YIELD OPTION-TM- NOTES DUE 2021
                            (ZERO COUPON -- SENIOR)
                                      AND
                           COMMON STOCK ISSUABLE UPON
                            CONVERSION OF THE LYONS

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    This document supplements the Prospectus dated June 18, 2001 relating to the
resale by the holders of Liquid Yield Option-TM- Notes (Zero Coupon--Senior) due
2021 (the "LYONs") and the shares of common stock issuable upon conversion of
the LYONs.

    This Prospectus Supplement is incorporated by reference into, and should be
read in conjunction with, the Prospectus dated June 18, 2001.

    The following sets forth information about the principal amount at maturity
of LYONs and the underlying common stock beneficially owned by each selling
securityholder that may be offered using this Prospectus. All information
concerning beneficial ownership has been provided by the selling securityholders
and is as of December 18, 2001.

- -TM-TRADEMARK OF MERRILL LYNCH & CO., INC.

                       ADDITIONAL SELLING SECURITYHOLDERS

    The table below lists an additional selling securityholder for the table on
page 37 of the Prospectus.



                                            AGGREGATE PRINCIPAL                  SHARES OF
                                              AMOUNT OF LYONS     PERCENTAGE    COMMON STOCK   PERCENTAGE OF
                                             AT MATURITY THAT      OF LYONS     THAT MAY BE     COMMON STOCK
NAME                                            MAY BE SOLD       OUTSTANDING     SOLD(1)      OUTSTANDING(2)
- ----                                        -------------------   -----------   ------------   --------------
                                                                                   
J.P. Morgan Securities Inc.(3)............      $32,000,000          12.7%        371,824           1.7%


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(1) Assumes conversion of all of the holder's LYONs at a conversion rate of
    11.6195 shares of common stock per $1,000 principal amount at maturity of
    the LYONs. However, this conversion rate will be subject to adjustment as
    described under "Description of LYONs--Conversion Right." As a result, the
    amount of common stock issuable upon conversion of the LYONs may increase or
    decrease in the future.

(2) Calculated based on Rule 13d-3(d)(i) of the Securities Exchange Act of 1934,
    as amended, using 22,136,869 shares of common stock outstanding as of
    May 30, 2001. In calculating this amount, we treated as outstanding that
    number of shares of common stock issuable upon conversion of all of that
    particular holder's LYONs. However, we did not assume the conversion of any
    other holder's LYONs.

(3) Although the total principal amount of selling securityholders listed is
    more than $251,000,000, the maximum principal amount of LYONs that may be
    sold under this prospectus will not exceed $251,000,000.

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    NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE
ADEQUACY OR ACCURACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
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          The date of this Prospectus Supplement is December 19, 2001.

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