ࡱ> hi l \pThe Free Software Foundation B=PF0*8X@"1 Helvetica1Courier1 Courier New1 Courier New1 Helvetica$#,##0_);($#,##0)$#,##0_);[Red]($#,##0)$#,##0.00_);($#,##0.00)$#,##0.00_);[Red]($#,##0.00)-**_($* #,##0_);_($* (#,##0);_($* "-"_);_(@_)*)'_(* #,##0_);_(* (#,##0);_(* "-"_);_(@_)5,2_($* #,##0.00_);_($* (#,##0.00);_($* "-"??_);_(@_)2+/_(* #,##0.00_);_(* (#,##0.00);_(* "-"??_);_(@_)2$#,##0.00;[Red]$#,##0.003$#,##0.00;[Red]($#,##0.00)4$#,##0;[Red]($#,##00)50.00%;[Red](0.00%)6 0%;[Red](0%)7#,##0.00;[Red](#,##0.00)8#,##0;[Red](#,##0)                + ) , *   Ј ~~ ؈ ~~#؈ ~~ ؈ ~~8#܈ ~~9#܈ ~~4#܈ ~~83ffff̙̙3f3fff3f3f33333f33NO TITLE NO TITLE (1)W NO TITLE (2);. NO TITLE (3)8 NO TITLE (4)3@ NO TITLE (5)W NO TITLE (6)o NO TITLE (7)x NO TITLE (8) NO TITLE (9)NO TITLE (10)&PIONEER NATURAL RESOURCES USA I&{PIONEER NATURAL RESOURCES U (1) l  %1 dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } 6} $ } } $ %    $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE             Page /'Report of Independent Registered Public~ Accounting Firm.&Statements of Net Assets Available for~ 1)Benefits as of December 31, 2021 and 20104,Statement of Changes in Net Assets Available~ 0(for Benefits for the Year Ended December31, 2011%Notes to Financial Statements~ 0(Schedule H; Line 4i - Schedule of Assets~ F5-(Held At End of Year) as of December 31, 2011 Signatures~ NIndex to Exhibits~ VDlznb29mI0 yU !"#$ !$"____________________________1#)Created by Morningstar Document Research.0$(http://documentresearch.morningstar.com/P=PF0*8X> @$$##"" l  " dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } 6} $                                $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE             December 31,  ~ n ~ j     !Investments at fair value~ FB~ %<*"Notes receivable from participants~ &~ B.&Contributions receivable from Employer~ Bj - Total assets~ V#hD~ ~=3+Unallocated accrued administrative expenses~ ~ ^U-%Net assets reflecting all investments~ VeD~ >=at fair value.&Adjustment from fair value to contract~ T~ ^65-value for fully benefit-responsive investment-%contracts held by a common/collectivetrust)!Net assets available for benefits~ 8D~  =$____________________________1)Created by Morningstar Document Research.0(http://documentresearch.morningstar.com/@ DznbJ_~~e}l=PF0*8X> @    l  %x+, dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } $ } } $ %    $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE          7 /Additions to net assets available for benefits:    Employer contributions~ #Participants' contributions~ $Interest and dividend income~ Ɛ Rollovers~ Other additions~ 8Total additions~ 8 0(Deductions from net assets available for benefits:%Distributions to participants~ R>5-Net depreciation in fair value of investments~ ?Administrative expenses~ ITotal deductions~ rE0(Net increase in net assets available for~ Jebenefits4,Net assets available for benefits, beginning~  =of year.&Net assets available for benefits, end~ 8DDlznb7a cN*|3k !"#$  of year!$"____________________________1#)Created by Morningstar Document Research.0$(http://documentresearch.morningstar.com/ P=PF0*8X> @ !$$##""   l  w7 dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } $                          $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE                 December 31,    ~ n ~ j         Vanguard PRIMECAP Fund~ f"~ rv ,$Pioneer Natural Resources Stock Fund~ rv~ 3 Vanguard 500 Index Fund~ 5~ 7  Vanguard Windsor II Fund~ Zy}~ ߛ ( Vanguard Prime Money Market Fund~ V~ j +#Vanguard Retirement Savings Trust V~  $____________________________1)Created by Morningstar Document Research.0(http://documentresearch.morningstar.com/4)znb>p9`TH =PF0*8X> @           l  ? dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } 6} $ } y} $     $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE     + #Registered investment company funds ~ *+ , $Pioneer Natural Resources Stock Fund  ~ V  Common/collective trusts  ~ > 5-Net depreciation in fair value of investments~ V$____________________________1)Created by Morningstar Document Research.0(http://documentresearch.morningstar.com/,|znb&o~rJ=PF0*8X> @*  l  #mUV dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } $ } } $ } } $ } $} $ } } $ #    $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE                       1 )Fair Value Measurements at Reporting Date     Using    5 -Quoted Prices in Active Markets for Identical + #Significant Other Observable Inputs ' Significant Unobservable Inputs ' Fair Value at December 31, 2011Assets (Level 2)   (Level 3) (Level 1)Assets:   ,$Registered investment company funds:   Money market fund~ V $-    $-~ V Bond funds~    -    -~  Balanced funds~ 6/   -    -~ 6/ Domestic stock funds~   -    -~ !International stock funds~ Fo  -    -~ FoReal estate fund~ C  -    -~ C!Common/collective trusts:   Sarofim Equity Fund (a) -~      -~ /'Vanguard Retirement Savings Trust V (b) -~      -~ ,$Pioneer Natural Resources Stock Fund~ rv  -    -~ rv~ F;~ T    $-~ FB   Dlznb~B*jITOY !"$ ____________________________1!)Created by Morningstar Document Research.0"(http://documentresearch.morningstar.com/ (=PF0*8X> @ !""!!             l  #m(n dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } $ } } $ } } $ } $} $ } } $ #    $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE                       1 )Fair Value Measurements at Reporting Date     Using    5 -Quoted Prices in Active Markets for Identical + #Significant Other Observable Inputs ' Significant Unobservable Inputs ' Fair Value at December 31, 2010Assets (Level 2)   (Level 3) (Level 1)Assets:   ,$Registered investment company funds:   Money market fund~ j $-    $-~ j Bond funds~ 2Jk  -    -~ 2JkBalanced funds~ k  -    -~ kDomestic stock funds~ zf  -    -~ zf!International stock funds~   -    -~ Real estate fund~ *#  -    -~ *#!Common/collective trusts:   Sarofim Equity Fund (a) -~  ^    -~ ^/'Vanguard Retirement Savings Trust V (b) -~  *    -~ *,$Pioneer Natural Resources Stock Fund~ 3  -    -~ 3~ "6~ sa    $-~ %<   Dlznb~B*jITOY !"$ ____________________________1!)Created by Morningstar Document Research.0"(http://documentresearch.morningstar.com/ (=PF0*8X> @ !""!!             l  w dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } $                         $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE              December 31,  ~ n ~ j1 )Net assets available for benefits per the ~ 8D  ~  = )!accompanying financial statements.&Adjustment from fair value to contract~ v,~  2*value for certain fully benefit-responsiveinvestment contracts2*Net assets available for benefits per Form~ VeD~ >= ~ U$____________________________1)Created by Morningstar Document Research.0(http://documentresearch.morningstar.com/2znbzNvh\4=PF0*8X> @          l  n dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } $ } } $     $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE         Year Ended   December 31, 20110 (Net increase in net assets available for~ Je /'benefits per the accompanying financial statements.&Adjustment from fair value to contract~ v,2*value for certain fully benefit responsive-%investment contracts, at December 31,~ n.&Adjustment from fair value to contract~ ^62*value for certain fully benefit responsive-%investment contracts, at December 31,~ j Net income per Form 5500~ v$____________________________1)Created by Morningstar Document Research.0(http://documentresearch.morningstar.com/>0znb&uB,m_TH<=PF0*8X> @     l  E  dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8)NO TITLE (10)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } } $ }  '} $ } :} $ } } $ E                                 $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE              (c)      (b) + #Description of investment including   (e)  % Identity of issuer, borrower, 4 ,maturity date, rate of interest, collateral,   Current (a) lessor, or similar partypar or maturity valueValue *( Vanguard Fiduciary Trust Company/'Vanguard PRIMECAP Fund - 552,608 shares~ f" *( Vanguard Fiduciary Trust Company0(Vanguard 500 Index Fund - 224,832 shares~ 5 *( Vanguard Fiduciary Trust Company1)Vanguard Windsor II Fund - 730,526 shares~ Zy} *( Vanguard Fiduciary Trust Company*"Vanguard Prime Money Market Fund -~ V16,807,125 shares *( Vanguard Fiduciary Trust Company80Vanguard Retirement Savings Trust V - 15,059,034~ sharesAmerican Funds/'American Funds Euro Pacific Growth Fund~ z -239,801 shares *( Vanguard Fiduciary Trust Company( Vanguard Total Bond Market Index~ Fund - 1,173,716 share *( Vanguard Fiduciary Trust Company+#Vanguard Intermediate-Term Treasury~ Fund -1,027,326 shares *( Vanguard Fiduciary Trust Company1)Vanguard Wellington Fund - 256,904 shares~ j"Sentinel Group Funds, Inc.-%Sentinel Small Company Fund - 953,864~ ֧Dlznb ZeLNMm#t"p. ! " # $ % & ' ( ) * + , - . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ?      shares !*!(! Vanguard Fiduciary Trust Company!0!(Vanguard Total International Stock Index!!~ !.!"""""Fund - 516,421 shares #*#(# Vanguard Fiduciary Trust Company#/#'Vanguard Inflation-Protected Securities##~ #:#$$$$$Fund - 483,702 shares %*%(% Vanguard Fiduciary Trust Company%.%&Vanguard Target Retirement 2020 Fund -%%~ %d%&&&&&'''''269,375 shares (*((( Vanguard Fiduciary Trust Company(.(&Vanguard Target Retirement 2015 Fund -((~ ( ()))))358,263 shares ***(* Vanguard Fiduciary Trust Company*.*&Vanguard Target Retirement 2025 fund -**~ *^b*+++++,,,,,473,841 shares--&-Franklin Templeton Investments-,-$Templeton Global Bond Fund - 283,585--~ --.....shares /*/(/ Vanguard Fiduciary Trust Company/./&Vanguard Total Stock Market Index Fund//~ /jg/0000 0-11111188,490 shares 2*2(2 Vanguard Fiduciary Trust Company2.2&Vanguard Target Retirement 2010 Fund -22~ 2"23333399,064 shares 4*4(4 Vanguard Fiduciary Trust Company4.4&Vanguard Target Retirement 2035 fund -44~ 4P45555566666373,669 shares777OppenheimerFunds Inc.7-7%Oppenheimer Developing Markets Fund -77~ 7.Ŗ78888885,268 shares 9*9(9 Vanguard Fiduciary Trust Company9.9&Vanguard Target Retirement 2005 fund -99~ 9 9:::::;;;;;244,209 shares <*<(< Vanguard Fiduciary Trust Company<-<%Vanguard Extended Market Index Fund -<<~ <!<=====53,363 shares>>>Loomis Sayles>0>(Loomis Sayles Bond Fund - 193,053 shares>>~ >N#> ?*?(? Vanguard Fiduciary Trust Company?.?&Vanguard Target Retirement 2030 Fund -??~ ?g?D.ltu:HV WY+-@ A B C D @@@@@160,084 sharesA$B____________________________1C)Created by Morningstar Document Research.0D(http://documentresearch.morningstar.com/KP=PF0*8X> @:DDCCBB   l  .P dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)!PIONEER NATURAL RESOURCES USA I!PIONEER NATURAL RESOURCES U (1)U } $} $ } m)} $ } 2} $ } y} $ .                                 $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012NO TITLE          * (  Vanguard Fiduciary Trust Company . &Vanguard Target Retirement 2045 fund -  ~            275,799 shares *( Vanguard Fiduciary Trust Company.&Vanguard Target Retirement 2040 Fund -~ .'149,576 sharesPIMCO0(PIMCO Total Return Fund - 204,018 shares~ V[Prudential Jennison-%Prudential Jennison Natural Resources~ ƇTfund - 29,880 shares *( Vanguard Fiduciary Trust Company.&Vanguard Target Retirement 2050 Fund -~ 6s92,486 sharesT. Rowe Price2*T. Rowe Price Mid-Cap Growth Fund - 34,212~ nsharesRoyce*"Royce Premier Fund - 67,947 shares~ ^KColumbia Acorn Funds2*Columbia Acorn International Fund - 32,237~ vCshares JP Morgan0(JP Morgan Small Cap Equity Fund - 35,266~ MsharesInvesco.&Invesco Real Estate Fund Institutional~ CClass - 48,494 sharesRoyce/'Royce Total Return Fund - 35,754 shares~  *( Vanguard Fiduciary Trust Company+#Vanguard Target Retirement Income -~ bP271,495 sharesDlznbA!{+v-F$G\ ! " # $ % & ' ( ) * + , -    Artisan Funds 2 *Artisan Mid Cap Value Fund - 31,739 shares  ~ )&  !*!(! Vanguard Fiduciary Trust Company!.!&Vanguard Target Retirement 2055 Fund -!!~ !!"""""13,880 shares###Fayez Sarofim & Co.#,#$Sarofim Equity Fund - 149,161 shares##~ ## $*$)$!Pioneer Natural Resources Company$.$&Pioneer Natural Resources Stock Fund -$$~ $rv$%%%%%845,553 units &*&*&"Notes receivable from participants&0&(Interest rates range from 4.25% to 9.25%&&~ &&&'''''with various maturities((((((~ (SD()*$+____________________________1,)Created by Morningstar Document Research.0-(http://documentresearch.morningstar.com/ v[]K?3 =PF0*8X> @"--,,++(( l   dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES U (1)U } } } 0     $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012+#PIONEER NATURAL RESOURCES USA, INC.    Date: June 22, 2012 By:    Susan A. Spratlen  0 (Member of Pioneer Natural Resources USA, Inc.*"401(k) and Matching Plan Committee$____________________________1)Created by Morningstar Document Research.0(http://documentresearch.morningstar.com/,?|wk_SG#h@=PF0*8X> @ l   dMbP?_*+%,&٭e2?'٭e2?(٭e2?)٭e2?",D/??  NO TITLE NO TITLE (1) NO TITLE (2) NO TITLE (3) NO TITLE (4) NO TITLE (5) NO TITLE (6) NO TITLE (7) NO TITLE (8) NO TITLE (9)NO TITLE (10)!PIONEER NATURAL RESOURCES USA IU } y } $ } 0} $ }      $PIONEER NATURAL RESOURCES CO 11-K 06/22/2012+#PIONEER NATURAL RESOURCES USA, INC.      Exhibit     Number   Description  Page     23.1 (a)0(Consent of Independent Registered Public~ ZAccounting Firm$____________________________1)Created by Morningstar Document Research.0(http://documentresearch.morningstar.com/.wk_SG w;^RF=PF0*8X> @ Root Entry FBook  5  !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefg