SECURITIES AND EXCHANGE COMMISSION
                       Washington, D.C.  20549

                             SCHEDULE 13G
              Under the Securities Exchange Act of 1934

                           (Amendment No. 12)*

                          CEMEX, S.A.B. de C.V.
         ________________________________________________________
                            (Name of Issuer)


                 Ordinary Participation Certificates
         _______________________________________________________
                    (Title of Class and Securities)

                               2406457
         _______________________________________________________

                 (CUSIP Number of Class of Securities)

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 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).





                  (Continued on following page(s))





CUSIP No. 2406457                                             13G
_____________________________________________________________________________
(1)  NAMES OF REPORTING PERSONS
     Southeastern Asset Management, Inc.      I.D. No. 62-0951781
_____________________________________________________________________________
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
_____________________________________________________________________________
(3)  SEC USE ONLY
_____________________________________________________________________________
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Tennessee
_____________________________________________________________________________
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
NUMBER OF SHARES BENEFICIALLY      :     756,898,437 shares
OWNED BY EACH REPORTING PERSON     __________________________________________
WITH                               :(6) SHARED OR NO VOTING POWER

                                         392,251,435 shares (Shared)
                                         190,466,444 shares (No Vote)
                                   __________________________________________
                                   :(7) SOLE DISPOSITIVE POWER
                                        (Discretionary Accounts)
                                   :     947,364,881 shares
                                   __________________________________________
                                   :(8)  SHARED DISPOSITIVE POWER

                                   :     392,251,435 shares (Shared)
                                                   0 shares (None)
_____________________________________________________________________________
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
     (Discretionary & Non-discretionary Accounts)

      1,339,616,316 shares
_____________________________________________________________________________
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES -X- See Items 4(c)(ii) and (iv)
_____________________________________________________________________________
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
       11.7 %
_____________________________________________________________________________
(12)  TYPE OF REPORTING PERSON
      IA
_____________________________________________________________________________










CUSIP No.  2406457                                     13G
_____________________________________________________________________________
(1)  NAMES OF REPORTING PERSONS
     O. Mason Hawkins                         I.D. No. XXX-XX-XXXX
_____________________________________________________________________________
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
_____________________________________________________________________________
(3)  SEC USE ONLY
_____________________________________________________________________________
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Citizen of United States
_____________________________________________________________________________
                                   :(5) SOLE VOTING POWER
                                   :   (Discretionary Accounts)
NUMBER OF SHARES BENEFICIALLY      :    None
OWNED BY EACH REPORTING PERSON     __________________________________________
WITH                               :(6) SHARED VOTING POWER

                                   :    None
                                   __________________________________________
                                   :(7) SOLE DISPOSITIVE POWER

                                   :    None
                                   __________________________________________
                                   :(8) SHARED DISPOSITIVE POWER

                                   :    None
_____________________________________________________________________________
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

       None (See Item 3)
_____________________________________________________________________________
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
_____________________________________________________________________________
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
       0.0 %
_____________________________________________________________________________
(12)  TYPE OF REPORTING PERSON
       IN
_____________________________________________________________________________



Item 1.

     (a). Name of Issuer: CEMEX, S.A.B. de C.V. ("Issuer")

     (b). Address of Issuer's Principal Executive Offices:

          Avenida Ricardo Margain Zozaya #325
          Colonia Valle del Campestre
          Garza Garcia, Nuevo Leon
          Mexico  66265


Item 2.

     (a). and (b). Names and Principal Business Addresses of Persons
          Filing

       (1)        Southeastern Asset Management, Inc.
                  6410 Poplar Ave., Suite 900
                  Memphis, TN 38119

       (3)        Mr. O. Mason Hawkins
                  Chairman of the Board and C.E.O.
                  Southeastern Asset Management, Inc.
                  6410 Poplar Ave., Suite 900
                  Memphis, TN 38119

     (c). Citizenship:

          Southeastern Asset Management, Inc. - A Tennessee corporation

          Mr. O. Mason Hawkins - U.S. Citizen

     (d). Title of Class of Securities: Ordinary Participation
          Certificates (the "Securities").

     (e). Cusip Number:  2406457


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

    (e). Investment Adviser registered under Section 203 of the
         Investment Advisers Act of 1940.  This statement is being filed
         by Southeastern Asset Management, Inc. as a registered investment
         adviser. All of the securities covered by this report are owned
         legally by Southeastern's investment advisory clients and none
         are owned directly or indirectly by Southeastern.  As permitted
         by Rule 13d-4, the filing of this statement shall not be construed
         as an admission that Southeastern Asset Management, Inc. is the
         beneficial owner of any of the securities covered by this statement.

   (g).  Parent Holding Company.  This statement is also being filed by
         Mr. O. Mason Hawkins, Chairman of the Board and C.E.O. of
         Southeastern Asset Management, Inc. in the event he could be
         deemed to be a controlling person of that firm as the result of
         his official positions with or ownership of its voting securities.
         The existence of such control is expressly disclaimed.  Mr. Hawkins
         does not own directly or indirectly any securities covered by
         this statement for his own account.  As permitted by Rule 13d-4,
         the filing of this statement shall not be construed as an admission
         that Mr. Hawkins is the beneficial owner of any of the securities
         covered by this statement.


Item 4. Ownership:

  (a). Amount Beneficially Owned: (At 12/31/12)

       1,339,616,316 shares.  This amount includes 496,716,282 in
       shares underlying convertible bonds.

  (b). Percent of Class:

        11.7 %

       Above percentage is based on 11,431,954,295 shares of Ordinary
       Participation Certificates outstanding.  The filers' holdings
       Consist of 129,723,631 American Depository shares (each
       representing 10 Ordinary Participation Certificates) and
       42,380,004 Ordinary Participation Certificates.

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

     (i).   sole power to vote or to direct the vote:

            756,898,437 shares.  This amount includes 104,464,847
            in shares underlying convertible bonds.

     (ii).  shared or no power to vote or to direct the vote:

            Shared - 392,251,435 shares.  Securities owned by
            the following series of Longleaf Partners Funds Trust, an
            open-end management investment company registered under the
            Investment Company Act of 1940, as follows:

            Longleaf Partners Fund - 321,493,119 shares
            Longleaf International Fund - 70,758,316 shares

            No Power to Vote - 190,466,444 shares.  This figure does
            not include 10,340,000 shares held by completely non-
            discretionary accounts over which the filing parties
            have neither voting nor dispositive power and for
            which the filing parties disclaim beneficial ownership.


     (iii). sole power to dispose or to direct the disposition of:

            947,364,881 shares.  This amount includes 104,464,847
            in shares underlying convertible bonds.

     (iv).  shared or no power to dispose or to direct the disposition
            of:

            Shared - 392,251,435 shares. Securities owned by the
            following series of Longleaf Partners Funds Trust, an
            open-end management investment company registered under the
            Investment Company Act of 1940, as follows:

            Longleaf Partners Fund - 321,493,119 shares
            Longleaf Partners International Fund - 70,758,316

            No Power - 0 shares.  This figure does not include
            10,340,000 shares held by completely non-discretionary
            accounts over which the filing parties have neither
            voting nor dispositive power and for which the filing
            parties disclaim beneficial ownership.


Item 5. Ownership of Five Percent or Less of a Class:  N/A


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:  N/A


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


Item 9. Notice of Dissolution of 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 in the
ordinary course of business and were not acquired for the purpose
and do not have 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
purposes or effect.



                           Signatures

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

Dated: February 14, 2013


                              Southeastern Asset Management, Inc.

                              By  /s/ Andrew R. McCarroll
                              ______________________________________________
                              Andrew R. McCarroll
                              Vice President and General Counsel


                              O. Mason Hawkins, Individually

                                /s/ O. Mason Hawkins
                              _______________________________________________



                      Joint Filing Agreement

In accordance with Rule 13d-1(k) under the Securities Exchange Act
of 1934, the persons or entities named below agree to the joint
filing on behalf of each of them of this Schedule 13G with respect
to the Securities of the Issuer and further agree that this joint
filing agreement be included as an exhibit to this Schedule 13G. In
evidence thereof, the undersigned hereby execute this Agreement as
of February 14, 2013.

                              Southeastern Asset Management, Inc.

                              By  /s/ Andrew R. McCarroll
                              _______________________________________________
                              Andrew R. McCarroll
                              Vice President and General Counsel


                              O. Mason Hawkins, Individually

                                /s/ O. Mason Hawkins
                             _______________________________________________



1
CMX13G12.doc
SCHEDULE 13G - CEMEX, S.A. de C.V. ("Issuer")
Amendment #12
2
CMX13G12.doc