SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G
                                (RULE 13d - 102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO 13d-1(b), (c) AND (d)
                  AND AMENDMENTS THERETO FILED PURSUANT TO 13d

                               (Amendment No. 1)*

        Affiliated Managers Group, Inc.
-----------------------------------------
(Name of Issuer)

        Common Stock
-----------------------------------------
(Title of Class of Securities)

        008252108
-----------------------------------------
(CUSIP Number)

        June 26, 2006
-----------------------------------------
(Date of Event which Requires Filing of this Statement)

Check the  appropriate box to designate the rule pursuant to which this Schedule
is filed:

[ ]      Rule 13d-1(b)
[x]      Rule 13d-1(c)
[ ]      Rule 13d-1(d)

*The  remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for  any  subsequent   amendment   containing   information  which  would  alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).

                       (Continued on the Following Pages)



1.       NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                  Amaranth LLC

2.       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

         (a)      [ ]
         (b)      [x]

3.       SEC USE ONLY

4.       CITIZENSHIP OR PLACE OF ORGANIZATION

                  Cayman Islands

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

5.       SOLE VOTING POWER

                  0

6.       SHARED VOTING POWER

                  969,918

7.       SOLE DISPOSITIVE POWER

                  0

8.       SHARED DISPOSITIVE POWER

                  969,918

9.       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  See 6 and 8 above.

10.      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9)
         EXCLUDES CERTAIN SHARES*   [ ]

11.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

                  3.0%

12.      TYPE OF REPORTING PERSON*

                  CO



1.       NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                  Amaranth Advisors L.L.C.

2.       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

         (a)      [ ]
         (b)      [x]

3.       SEC USE ONLY

4.       CITIZENSHIP OR PLACE OF ORGANIZATION

                  Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:

5.       SOLE VOTING POWER

                  0

6.       SHARED VOTING POWER

                  969,918

7.       SOLE DISPOSITIVE POWER

                  0

8.       SHARED DISPOSITIVE POWER

                  969,918

9.       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                  See 6 and 8 above.

10.      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9)
         EXCLUDES CERTAIN SHARES*   [ ]

11.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

                  3.0%

12.      TYPE OF REPORTING PERSON*

                  IA



1.       NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

                  Nicholas M. Maounis

2.       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

         (a)      [ ]
         (b)      [x]

3.       SEC USE ONLY

4.       CITIZENSHIP OR PLACE OF ORGANIZATION

                  United States

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.       SOLE VOTING POWER

                  0

6.       SHARED VOTING POWER

                  969,918

7.       SOLE DISPOSITIVE POWER

                  0

8.       SHARED DISPOSITIVE POWER

                  969,918

9.       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                  See 6 and 8 above.

10.      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9)
         EXCLUDES CERTAIN SHARES*   [ ]

11.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

                  3.0%

12.      TYPE OF REPORTING PERSON*

                  IN, HC



This statement is filed with respect to the shares of common stock,  having $.01
par value (the "Common Stock") of Affiliated Managers Group, Inc. (the "Issuer")
beneficially owned by Amaranth LLC, a Cayman Islands exempted company,  Amaranth
Advisors L.L.C. and Nicholas M. Maounis (collectively,  the "Reporting Persons")
as of July 19, 2006 and amends and  supplements the Schedule 13G filed April 27,
2006 (the  "Schedule  13G").  Except as set forth  herein,  the  Schedule 13G is
unmodified.

Item 4.   Ownership.

     Provide  the  following  information  regarding  the  aggregate  number and
percentage of the class of securities of the issuer identified in Item 1.

     (a)  Amount beneficially owned:

          The Reporting Persons  beneficially own 969,918 shares of the Issuer's
          Common  Stock,  which are comprised of (i) 900 shares of Common Stock,
          (ii) shares of the Issuer's 6.65%  convertible  preferred  stock which
          are  convertible  into an aggregate of 441,939 shares of Common Stock,
          and  (iii)  4.3%  convertible  debentures  of  the  Issuer  which  are
          convertible into 527,079 shares of Common Stock.

     (b)  Percent of class:

          3.0%

     (c)  Number of shares as to which such person has:

          (i)   Sole power to vote or direct the vote

                0

          (ii)  Shared power to vote or to direct the vote

                See Item 4(a).

          (iii) Sole power to dispose or to direct the disposition of

                0

          (iv)  Shared power to dispose or to direct the disposition of

                See Item 4(a).

Item 5.   Ownership of Five Percent or Less of a Class.

     If this  statement  is being  filed to report  the fact that as of the date
hereof the Reporting Persons have ceased to be the beneficial owner of more than
five  percent of the class of  securities,  check the  following  [X].



Item 10.  Certification.

     By  signing  below  the  undersigned  certifies  that,  to the  best of its
knowledge and belief, the securities referred to above were not acquired and are
not held for the purpose of or with the effect of changing  or  influencing  the
control of the issuer of the  securities  and were not acquired and are not held
in connection with or as a participant in any transaction having that purpose or
effect.



                                   SIGNATURES

     After reasonable inquiry and to the best of its knowledge and belief,  each
of the undersigned  certifies that the information  with respect to it set forth
in this statement is true, complete, and correct.


Dated:   July 19, 2006

         AMARANTH LLC
            by Amaranth Advisors L.L.C., as Trading Advisor

            By: /s/ Nicholas M. Maounis
                ----------------------------------------
                    Nicholas M. Maounis, Managing Member


         AMARANTH ADVISORS L.L.C.

            By: /s/ Nicholas M. Maounis
                ----------------------------------------
                    Nicholas M. Maounis, Managing Member


         NICHOLAS M. MAOUNIS

            /s/ Nicholas M. Maounis
            -----------------------
                Nicholas M. Maounis