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

                                 SCHEDULE 13G/A

                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                               (AMENDMENT NO. 4)*

                               Griffon Corporation
                               -------------------
                                (Name of Issuer)

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

                                    398433102
                                 --------------
                                 (CUSIP Number)

                                December 31, 2008
             -------------------------------------------------------
             (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).


                                PAGE 1 OF 4 PAGES

--------------------------------------------------------------------------------
 1     NAME OF REPORTING PERSON
       S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

       NWQ Investment Management Company, LLC     47-0875103
--------------------------------------------------------------------------------
 2     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*        (a) [-]
                                                                (b) [-]
--------------------------------------------------------------------------------
 3     SEC USE ONLY

--------------------------------------------------------------------------------
 4     CITIZENSHIP OR PLACE OF ORGANIZATION

       Delaware - U.S.A.
--------------------------------------------------------------------------------
                     5      SOLE VOTING POWER

                            4,442,996
      NUMBER OF      -----------------------------------------------------------
        SHARES       6      SHARED VOTING POWER
     BENEFICIALLY
       OWNED BY             0
         EACH        -----------------------------------------------------------
      REPORTING      7      SOLE DISPOSITIVE POWER
       PERSON
         WITH               4,876,404
                     -----------------------------------------------------------
                     8      SHARED DISPOSITIVE POWER

                            0
--------------------------------------------------------------------------------
 9     AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

       4,876,404
--------------------------------------------------------------------------------
10     CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

       N/A
--------------------------------------------------------------------------------
11     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

       8.23%
--------------------------------------------------------------------------------
12     TYPE OF REPORTING PERSON*

       IA
--------------------------------------------------------------------------------
*Reflects the reporting person's ownership as of December 31, 2008, including
shares of the issuer which may be issued upon conversion of 4.00% Convertible
Senior Subordinated Notes due 7/18/23.


                               PAGE 2 OF 4 PAGES


              Item 1(a) Name of Issuer:
                        Griffon Corporation

              Item 1(b) Address of Issuer's Principal Executive Offices:
                        100 Jericho Quadrangle
                        Jerico, New York 11753
                        United States

              Item 2(a) Name of Person Filing:
                        NWQ Investment Management Company, LLC

              Item 2(b) Address of the Principal Office or, if none, Residence:
                        2049 Century Park East, 16th Floor
                        Los Angeles, CA  90067

              Item 2(c) Citizenship:
                        Delaware - U.S.A.

              Item 2(d) Title of Class of Securities:
                        Common

              Item 2(e) CUSIP Number:
                        398433102

              Item 3    If the Statement is being filed pursuant to Rule
                        13d-1(b), or 13d-2(b), check whether the person filing
                        is a:

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

              Item 4    Ownership:
                        (a) Amount Beneficially Owned:
                            4,876,404

                        (b) Percent of Class:
                            8.23%

                        (c) Number of shares as to which such person has:
                            (i)   sole power to vote or direct the vote:
                                          4,442,996
                            (ii)  shared power to vote or direct the vote:
                                  0

                            (iii) sole power to dispose or to direct the
                                  disposition of:
                                  4,876,404

                            (iv)  shared power to dispose or to direct the
                                  disposition of:
                                  0

              Item 5    Ownership of Five Percent or Less of a Class:
                        Not applicable.


                                PAGE 3 OF 4 PAGES


              Item 6    Ownership of More than Five Percent on Behalf of Another
                        Person:
                        Securities reported on this Schedule 13G are
                        beneficially owned by clients of the adviser, which may
                        include investment companies registered under the
                        Investment Company Act and/or employee benefit plans,
                        pensions, Charitable funds or other institutional and
                        high net worth clients.

              Item 7    Identification and Classification of the Subsidiary
                        Which Acquired the Security Being Reported on By the
                        Parent Holding Company:
                        Not applicable.

              Item 8    Identification and Classification of Members of the
                        Group:
                        Not applicable.

              Item 9    Notice of Dissolution of a Group:
                        Not applicable.

              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 such securities and were
                        not acquired in connection with or as a participant in
                        any transaction having such purpose or effect.

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.

Dated: February 13, 2009

                                 NWQ Investment Management Company, LLC

                                 By:   /S/ Jon D. Bosse
                                       ----------------
                                 Jon D. Bosse, CFA
                                 Title: Chief Investment Officer


                                PAGE 4 OF 4 PAGES