SECURITIES AND EXCHANGE COMMISSION
Washington, D.C.  20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No. 6)*
Pioneer Natural Resources Company
________________________________________________________
(Name of Issuer)
Common Stock
_______________________________________________________
(Title of Class and Securities)
723787107
_______________________________________________________
(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. 723787107                                             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      :      7,948,494 shares
OWNED BY EACH REPORTING PERSON     __________________________________________
WITH                               :(6) SHARED OR NO VOTING POWER
                                         10,257,000 shares (shared)
                                            2,382,900 shares (No Vote)
                                   __________________________________________
                                   :(7) SOLE DISPOSITIVE POWER
                                        (Discretionary Accounts)
                                   :       10,297,394 shares
                                   __________________________________________
                                   :(8)  SHARED DISPOSITIVE POWER
                                   :     10,257,000 shares (Shared)
                                            34,000 shares (None)
_____________________________________________________________________________
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
        20,588,394 shares
_____________________________________________________________________________
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
_____________________________________________________________________________
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
       17.6 %
_____________________________________________________________________________
(12)  TYPE OF REPORTING PERSON
      IA
_____________________________________________________________________________
CUSIP No. 723787107                                             13G
_____________________________________________________________________________
(1)  NAMES OF REPORTING PERSONS
 	Longleaf Partners Fund			I.D. No. 63-6147721
_____________________________________________________________________________
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP:
                                              (a)
                                              (b) X
_____________________________________________________________________________
(3)  SEC USE ONLY
_____________________________________________________________________________
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION
     Massachusetts Business Trust
_____________________________________________________________________________
                                   :(5) SOLE VOTING POWER
                                   :
NUMBER OF SHARES BENEFICIALLY      :    None
OWNED BY EACH REPORTING PERSON     __________________________________________
WITH                               :(6) SHARED OR NO VOTING POWER
                                         10,257,000 shares (shared)
                                   __________________________________________
                                   :(7) SOLE DISPOSITIVE POWER
                                   :    None
                                   __________________________________________
                                   :(8)  SHARED DISPOSITIVE POWER
                                   :     10,257,000 shares (Shared)
_____________________________________________________________________________
(9)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
        10,257,000 shares
_____________________________________________________________________________
(10)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES
      CERTAIN SHARES
_____________________________________________________________________________
(11)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
       8.8 %
_____________________________________________________________________________
(12)  TYPE OF REPORTING PERSON
      IV
_____________________________________________________________________________
CUSIP No.  723787107                                     13G
_____________________________________________________________________________
(1)  NAMES OF REPORTING PERSONS
     O. Mason Hawkins                         I.D. No. ###-##-####
_____________________________________________________________________________
(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: Pioneer Natural Resources Company
          ("Issuer")
     (b). Address of Issuer's Principal Executive Offices:
          1400 Williams Square West
	    5205 N. O'Connor Blvd.
          Irving, Texas 75039
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
(2) Longleaf Partners Fund
c/o Southeastern Asset Management, Inc.
6410 Poplar Avenue, 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
Longleaf Partners Fund, a series of Longleaf Partners
Funds Trust, a Massachusetts business trust
       Mr. O. Mason Hawkins - U.S. Citizen
     (d). Title of Class of Securities:  Common Stock (the
            "Securities").
     (e). Cusip Number:  723787107
Item 3.  If this statement is filed pursuant to Rules 13d-1 (b) or
 13d-2 (b), check whether the person filing is a:
(d.) Investment Company registered under Sec. 8 of the Investment
       Company Act - Longleaf Partners Fund, a series of
       Longleaf Partners Funds Trust.
(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 12/31/02)
            20,588,394 shares
     (b). Percent of Class:
            17.6 %
          Above percentage is based on 117,044,020 shares of Common
          Stock outstanding.
     (c). Number of shares as to which such person has:
          (i).   sole power to vote or to direct the vote:
                    7,948,494 shares
          (ii).  shared or no power to vote or to direct the vote:
                 Shared - 10,257,000 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 - 10,257,000
       No Power to Vote - 2,382,900.
          (iii). sole power to dispose or to direct the disposition
                 of:
                    10,297,394 shares
          (iv).  shared or no power to dispose or to direct the
                 disposition of:
                 Shared - 10,257,000 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 - 10,257,000
       No Power - 34,000 shares.
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: January 8, 2022
                              Southeastern Asset Management, Inc.
                              By  /s/ Andrew R. McCarroll
 					_______________________________________________
       Andrew R. McCarroll
                              Vice President and General Counsel
Longleaf Partners Fund
By: Southeastern Asset Management, Inc.
                              /s/ Andrew R. McCarroll
 					_______________________________________________
       Andrew R. McCarroll
                              Vice President & General Counsel
                              O. Mason Hawkins, Individually
                                /s/ O. Mason Hawkins
                              _______________________________________________
                       Joint Filing Agreement
In accordance with Rule 13d-1(f) 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 January 8, 2003.
       Southeastern Asset Management, Inc.
                              By  /s/ Andrew R. McCarroll
 					_______________________________________________
       Andrew R. McCarroll
                              Vice President and General Counsel
Longleaf Partners Fund
                              By: Southeastern Asset Management, Inc.
                              /s/ Andrew R. McCarroll
 					_______________________________________________
       Andrew R. McCarroll
                              Vice President & General Counsel
                              O. Mason Hawkins, Individually
                                /s/ O. Mason Hawkins
                              _______________________________________________

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