UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                               (Amendment No. 2)*


                                  Sigma-Aldrich
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                                (Name of Issuer)


                                  Common Stock
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                         (Title of Class of Securities)


                                    826552101
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                                 (CUSIP Number)



                                January 31, 2007
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


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

         [X]   Rule 13d-1(b)

         [ ]   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 the
disclosures provided in a prior cover page.

The information required in 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).



                                  SCHEDULE 13G

CUSIP No.         826552101

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          1.   Names of Reporting Persons.  I.R.S.  Identification Nos. of above
               persons (entities only).
               AMVESCAP PLC
               AIM Advisors, Inc.
               AIM Funds Management, Inc.
               AIM Private Asset Management, Inc.
               PowerShares Capital Management LLC
               INVESCO Asset Management Limited
               INVESCO Institutional (N.A.), Inc.
               Stein Roe Investment Counsel, Inc.
               INVESCO GT Management Company S.A.
               Atlantic Trust Company, N.A.
               INVESCO Kapitalanlagegesellschaft GmbH

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          2.   Check the Appropriate Box if a Member of a Group (see
               Instructions)
               (a)
               (b)

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          3.   SEC Use Only  _______________________________________________

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          4.   Citizenship or Place of Organization
               AMVESCAP PLC: England
                  AIM Advisors, Inc.:  United States
                  AIM Funds Management, Inc.: United States
                  AIM Private Asset Management, Inc.: United States
                  PowerShares Capital Management LLC:  United States
                  INVESCO Asset Management Limited:  England
                  INVESCO Institutional (N.A.), Inc.: United States
                  Stein Roe Investment Counsel, Inc.:  United States
               INVESCO GT Management Company S.A.:  Luxembourg
               Atlantic Trust Company, N.A.: United States
                  INVESCO Kapitalanlagegesellschaft GmbH:  Germany
--------------------------------------------------------------------------------

                            5.      Sole Voting Power 5,215,241: Such
                                    shares are held by the following
                                    entities in the respective amounts
                                    listed:
                                    AIM Advisors, Inc. 2,203,252
                                    AIM Funds Management, Inc. 1,430,848
                                    AIM Private Asset Management, Inc. 1,189,927
                                    PowerShares Capital Management LLC 209,269
                                    INVESCO Asset Management Limited  142,800
                                    INVESCO Institutional (N.A.), Inc. 17,645
                                    Stein Roe Investment Counsel, Inc. 6,900
                                    INVESCO GT Management Company S.A.  4,600
                                    Atlantic Trust Company, N.A.  3,600
                                    INVESCO Kapitalanlagegesellschaft GmbH 6,400
Number of Shares           -----------------------------------------------------
Beneficially Owned
by Each Reporting           6.      Shared Voting Power            -0-
Person With
                           -----------------------------------------------------

                            7.      Sole Dispositive Power 5,215,241: Such
                                    shares are held by the following
                                    entities in the respective amounts
                                    listed:
                                    AIM Advisors, Inc. 2,203,252
                                    AIM Funds Management, Inc. 1,430,848
                                    AIM Private Asset Management, Inc. 1,189,927
                                    PowerShares Capital Management LLC  209,269
                                    INVESCO Asset Management Limited  142,800
                                    INVESCO Institutional (N.A.), Inc. 17,645
                                    Stein Roe Investment Counsel, Inc. 6,900
                                    INVESCO GT Management Company S.A.  4,600
                                    Atlantic Trust Company, N.A.  3,600
                                    INVESCO Kapitalanlagegesellschaft GmbH 6,400

                           -----------------------------------------------------

                           8.      Shared Dispositive Power        -0-

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          9.   Aggregate  Amount  Beneficially  Owned by Each  Reporting  Person
               5,215,241

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          10.  Check if the Aggregate  Amount in Row (9) Excludes Certain Shares
               (See Instructions) N/A

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          11.  Percent of Class Represented by Amount in Row (9)        3.95%

--------------------------------------------------------------------------------

          12.  Type of Reporting Person (See  Instructions)
               IA, HC. See Items 2 and 3 of this statement.
--------------------------------------------------------------------------------



                                 SCHEDULE 13G


Item 1(a)         Name of Issuer:
                  Sigma-Aldrich

Item 1(b)         Address of Issuer's Principal Executive Offices:
                  3050 Spruce Street
                  St. Louis, MO  63103

Item 2(a)         Name of Person Filing:
                  AMVESCAP PLC

                  In accordance with Securities and Exchange Commission Release
                  No. 34-39538 (January 12, 1998), this statement on Schedule
                  13G or amendment thereto is being filed by AMVESCAP PLC
                  ("AMVESCAP"), a U.K. entity, on behalf of itself and its
                  subsidiaries listed in Item 4 of the cover of this statement.
                  AMVESCAP through such subsidiaries provides investment
                  management services to institutional and individual investors
                  worldwide.

                  Executive officers and directors of AMVESCAP or its
                  subsidiaries may beneficially own shares of the securities of
                  the issuer to which this statement relates (the "Shares"), and
                  such Shares are not reported in this statement. AMVESCAP and
                  its subsidiaries disclaim beneficial ownership of Shares
                  beneficially owned by any of their executive officers and
                  directors. Each of AMVESCAP's direct and indirect subsidiaries
                  also disclaim beneficial ownership of Shares beneficially
                  owned by AMVESCAP and any other subsidiary.

Item 2(b)         Address of Principal Business Office:
                  30 Finsbury Square
                  London EC2A 1AG
                  England

Item 2(c)         Citizenship:
                  See the response to Item 2(a) of this statement.

Item 2(d)         Title of Class of Securities:
                  Sponsored ADR, $.01 par value per share

Item 2(e)         CUSIP Number:
                  826552101

Item              3 If this statement is filed pursuant to ss240.13d-1(b) or
                  240.13d-2(b) or (c), check whether the person filing is a:

          (e) [x] An investment adviser in accordance with section 240.13d-1(b)
                  (1)(ii)(E)

          (g) [x] A parent holding company or control person in accordance with
                  section 240.13d-1(b)(1)(ii)(G)

                  As noted in Item 2 above, AMVESCAP is making this filing on
                  behalf of its subsidiaries listed herein. Each of these
                  entities is either an investment adviser registered with the
                  United States Securities and Exchange Commission under Section
                  203 of the Investment Advisers Act of 1940, as amended, or
                  under similar laws of other jurisdictions. AMVESCAP is a
                  holding company.



Item 4            Ownership:
                  Please see responses to Items 5-8 on the cover of this
                  statement, which are incorporated herein by reference.

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 person has ceased to
                      be the beneficial owner of more than five percent of the
                      class of securities, check the following [ x ]

Item 6            Ownership of More than Five Percent on Behalf of Another
                  Person: N/A

Item 7            Identification and Classification of the Subsidiary Which
                  Acquired the Security Being reported on By the Parent Holding
                  Company:
                  Please see Item 3 of this statement, which is incorporated
                  herein by reference.

Item 8            Identification and Classification of Members of the Group:
                  N/A

Item 9            Notice of Dissolution of a Group:
                  N/A

Item 10           Certification:
                  By signing below I certify that, to the best of my knowledge
                  and belief, the securities referred to above were acquired and
                  are held in the ordinary course of business and 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.

                  Signature:
                  After reasonable inquiry and to the best of my knowledge and
                  belief, I certify that the information set forth in this
                  statement is true, complete and correct.


                                                     February 9, 2007
                                            ------------------------------------
                                                        Date

                                            AMVESCAP PLC

                                            By:      /s/ Lisa Brinkley
                                            ------------------------------------
                                                     Lisa Brinkley
                                                Global Compliance Director



                                INDEX TO EXHIBIT


EXHIBIT NUMBER             DESCRIPTION

     A                     JOINT FILING AGREEMENT





EXHIBIT A

                             JOINT FILING AGREEMENT
                             ----------------------

In accordance with Rule 13d-1(k)(l) under the Securities Exchange Act of 1934,
as amended, the undersigned hereby agree to the joint filing of the attached
Schedule 13G, and any and all amendments thereto, and expressly authorize
AMVESCAP PLC, as the ultimate parent company of each of its undersigned
subsidiaries, to file such Schedule 13G, and any and all amendments thereto, on
behalf of each of them.


Dated: February 9, 2007               AMVESCAP PLC

                                       By: /s/ Lisa Brinkley
                                          ----------------------------
                                       Name:  Lisa Brinkley
                                       Title: Global Compliance Director


                                       AIM Advisors, Inc.

                                       By: /s/ Todd L. Spillane
                                          ----------------------------
                                       Name:  Todd L. Spillane
                                       Title: Chief Compliance Officer

                                             AIM Funds Management, Inc.

                                       By: /s/ Wayne Bolton
                                          ----------------------------
                                       Name:  Wayne Bolton
                                       Title: Vice President, Compliance
                                              & Chief Compliance Officer

                                              AIM Private Asset Management, Inc.

                                       By: /s/ Todd L. Spillane
                                          ----------------------------
                                       Name:  Todd L. Spillane

                                             PowerShares Capital Management LLC

                                      By: /s/ Kevin Gustafson
                                          ----------------------------
                                      Name:  Kevin Gustafson
                                      Title: General Counsel & COO

                                            INVESCO Asset Management Limited

                                       By: /s/ Nick Styman
                                          ----------------------------
                                       Name:  Nick Styman
                                       Title: Director of European Compliance

                                            INVESCO Institutional (N.A.), Inc.

                                       By: /s/ Jeffrey Kupor
                                          ----------------------------
                                       Name:  Jeffrey Kupor
                                       Title: General Counsel

                                             Stein Roe Investment Counsel, Inc.

                                       By: /s/ Greg Campbell
                                          ----------------------------
                                              Name:  Greg Campbell
                                       Title: General Counsel

                                             INVESCO GT Management Company S.A.

                                       By: /s/ Nick Styman
                                          ----------------------------
                                       Name:  Nick Styman
                                       Title: Director of European Compliance