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                                                                    EXHIBIT 10.2

                            STOCK PURCHASE AGREEMENT


         This Stock Purchase Agreement (this "Agreement") is made and entered
into this 28th day of March, 2000, by and between Prize Energy Corp. (formerly
known as Vista Energy Resources, Inc.), a Delaware corporation ("Prize"), and
Pioneer Natural Resources USA, Inc., a Delaware corporation ("Pioneer").

                                    RECITALS

         A. On February 8, 2000, as the result of a merger, Pioneer acquired
3,984,197 shares of Series A 6% Convertible Preferred Stock of Prize (the
"Pioneer Preferred Shares").

         B. On March 31, 2000, Pioneer will be entitled to a dividend with
respect to the Pioneer Preferred Shares which the Parties (as defined below)
desire to have paid in cash in the amount of $458,514.

         C. Prize desires that Pioneer convert the Pioneer Preferred Shares to
shares of common stock, par value $.01 per share, of Prize ("Common Stock"), and
Pioneer is willing to convert the Pioneer Preferred Shares to shares of Common
Stock provided Prize purchases a portion of such shares immediately upon the
conversion as described below.

         D. Pioneer and Prize (the "Parties") desire to enter into this
Agreement in order to set forth their respective rights and obligations with
respect to such transaction and certain other matters.

         E. On February 8, 2000, Prize, Pioneer and certain other stockholders
of Prize entered into a certain Voting and Shareholders Agreement, providing,
among other things, for the right of Pioneer to designate two members of the
board of directors of Prize (the "Voting Agreement").

         F. On June 29, 1999, Pioneer and Prize Natural Resources, Inc.
(formerly known as Prize Energy Corp.), a Delaware corporation which is now a
wholly-owned subsidiary of Prize ("Old Prize"), entered into a certain Joint
Participation Agreement, providing, among other things, for Pioneer's right to
participate in certain future projects of Prize (the "Joint Participation
Agreement"). On February 8, 2000, the rights and obligations of Old Prize under
the Joint Participation Agreement were assigned to and assumed by Prize.

         In consideration of the premises and the mutual covenants herein
contained, the Parties hereby agree as follows:

         1. Effective Date. All of the transactions set forth herein shall be
effective as of the close of business on March 31, 2000 (the "Effective Date"),
and the closing shall occur immediately before the close of business on that
date (the "Closing").

         2. Payment of Dividend. On the Effective Date and before the Closing,
Prize shall pay to Pioneer, by wire transfer of immediately available funds to
an account designated by Pioneer, the amount of $458,514 as a dividend on the
Pioneer Preferred Shares.

         3. Conversion of the Pioneer Preferred Shares. Effective as of the
Effective Date, the Pioneer Preferred Shares shall, without further action on
the part of either Party or any other person or entity, be converted into
3,984,197 shares of Common Stock.

         4. Purchase and Sale. Effective as of the Effective Date, Prize shall
purchase from Pioneer, and Pioneer shall sell and deliver to Prize, 1,346,482
shares of Common Stock (the "Pioneer Shares"). At the Closing: (a) Pioneer shall
deliver to Prize the stock certificates evidencing the Pioneer Preferred Shares,
duly endorsed for transfer or accompanied by duly executed stock powers; and (b)
Prize shall deliver to Pioneer a certificate evidencing 2,637,715


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shares of Common Stock or, if impracticable, an irrevocable letter of
instruction to Prize's transfer agent instructing that a certificate evidencing
2,637,715 shares of Common Stock be delivered to Pioneer not later than April 7,
2000.

         5. Purchase Price. In consideration for the purchase and sale of the
Pioneer Shares, Prize shall pay to Pioneer at the Closing, by wire transfer of
immediately available funds to an account designated by Pioneer, an amount equal
to $13.50 per Pioneer Share, for a total purchase price of $18,177,507.

         6. Voting Agreement. Effective as of the Effective Date, subject to the
receipt of the payment of the dividend and purchase price as set forth herein,
Pioneer hereby relinquishes all of its rights under the Voting Agreement,
including without limitation its right to designate two directors of Prize. Not
later than April 7, 2000, subject to the receipt of the payment of the dividend
and purchase price as set forth herein, Pioneer shall deliver to Prize the
written resignations of each of its designated members of Prize's board of
directors, effective as of the Effective Date.

         7. Joint Participation Agreement. Pioneer, subject to the receipt of
the payment of the dividend and purchase price as set forth herein, and Prize
hereby agree to terminate the Joint Participation Agreement as of the Effective
Date and further agree that neither Party shall have any liability or obligation
to the other under the Joint Participation Agreement following the Closing.

         8. Representations and Warranties of Pioneer. Pioneer hereby represents
and warrants to Prize as follows:

            (a) Organization and Authority. Pioneer is a corporation, duly
         organized, validly existing and in good standing under the laws of the
         State of Delaware and has all requisite power and authority to own,
         lease and operate its properties and to conduct its business as
         presently conducted. Pioneer has full power and authority to execute
         and deliver this Agreement and to perform its obligations hereunder. No
         further action is necessary on the part of Pioneer for Pioneer to
         execute and deliver this Agreement and to consummate and perform its
         obligations hereunder.

            (b) Validity and Binding Effect. This Agreement has been duly
         executed and delivered on behalf of Pioneer and constitutes the legal,
         valid and binding obligation of Pioneer, enforceable against Pioneer in
         accordance with its terms, except as the same may be limited by
         applicable bankruptcy, insolvency, reorganization, moratorium or
         similar laws affecting the enforcement of creditor's rights generally
         and general equitable principles, regardless of whether enforceability
         is considered in a proceeding at law or in equity.

            (c) Litigation. There is no litigation, proceeding or investigation
         pending or, to the knowledge of Pioneer, threatened against or
         affecting Pioneer that questions the validity or enforceability of this
         Agreement or any other document, instrument or agreement to be executed
         and delivered by Pioneer in connection with the transactions
         contemplated hereby.

            (d) Noncontravention. Neither the execution and delivery of this
         Agreement, nor the consummation of the transactions contemplated
         hereby, will (i) violate any statute, regulation, rule, injunction,
         judgment, order, decree or ruling, charge or other restriction of any
         government, governmental agency, or court to which Pioneer is subject;
         or (ii) conflict with, result in a breach of, constitute a default
         under, result in the acceleration of, create in any Party the right to
         accelerate, terminate, modify or cancel, or require any notice or
         consent under the Certificate of Incorporation or Bylaws of Pioneer or
         any agreement, contract, lease, license, instrument or other
         arrangement to which Pioneer is a Party or by which Pioneer is bound or
         to which any of its assets are subject.

            (e) Consents and Approvals. No consent, approval, order or
         authorization of, registration, declaration or filing with, or permit
         from, any governmental authority is required by or with respect to
         Pioneer in connection with the execution and delivery of this Agreement
         by Pioneer or the consummation by Pioneer of the transactions
         contemplated hereby. No consent or approval of any other person or
         entity is required by or with respect to Pioneer in connection with the
         execution and delivery of this Agreement or the consummation of the
         transactions contemplated hereby.


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            (f) Title to the Pioneer Preferred Shares and the Pioneer Shares.
         The Pioneer Preferred Shares are held, and the Pioneer Shares, upon
         issuance, will be held, beneficially and of record by Pioneer, and the
         Pioneer Shares are being conveyed to Prize free and clear of any lien,
         mortgage, security interest, pledge, deposit, burden, encumbrance,
         restriction on transfer, option, warrant, purchase right or other
         contract or commitment (other than this Agreement and the Voting
         Agreement).

         9. Representations and Warranties of Prize. Prize hereby represents and
warrants to Pioneer as follows:

            (a) Organization and Authority. Prize is a corporation, duly
         organized, validly existing and in good standing under the laws of the
         State of Delaware and has all requisite power and authority to own,
         lease and operate its properties and to conduct its business as
         presently conducted. Prize has full power and authority to execute and
         deliver this Agreement and to perform its obligations hereunder. No
         further action is necessary on the part of Prize for Prize to execute
         and deliver this Agreement and to consummate and perform its
         obligations hereunder.

            (b) Validity and Binding Effect. This Agreement has been duly
         executed and delivered on behalf of Prize and constitutes the legal,
         valid and binding obligation of Prize, enforceable against Prize in
         accordance with its terms, except as the same may be limited by
         applicable bankruptcy, insolvency, reorganization, moratorium or
         similar laws affecting the enforcement of creditor's rights generally
         and general equitable principles, regardless of whether enforceability
         is considered in a proceeding at law or in equity.

            (c) Litigation. There is no litigation, proceeding or investigation
         pending or, to the knowledge of Prize, threatened against or affecting
         Prize that questions the validity or enforceability of this Agreement
         or any other document, instrument or agreement to be executed and
         delivered by Prize in connection with the transactions contemplated
         hereby.

            (d) Noncontravention. Neither the execution and delivery of this
         Agreement, nor the consummation of the transactions contemplated
         hereby, will (i) violate any statute, regulation, rule, injunction,
         judgment, order, decree or ruling, charge or other restriction of any
         government, governmental agency, or court to which Prize is subject; or
         (ii) conflict with, result in a breach of, constitute a default under,
         result in the acceleration of, create in any Party the right to
         accelerate, terminate, modify or cancel, or require any notice or
         consent under the Certificate of Incorporation or Bylaws of Prize or
         any agreement, contract, lease, license, instrument or other
         arrangement to which Prize is a Party or by which Prize is bound or to
         which any of its assets are subject.

            (e) Consents and Approvals. No consent, approval, order or
         authorization of, registration, declaration or filing with, or permit
         from, any governmental authority is required by or with respect to
         Prize in connection with the execution and delivery of this Agreement
         by Prize or the consummation by Prize of the transactions contemplated
         hereby. No consent or approval of any other person or entity is
         required by or with respect to Prize in connection with the execution
         and delivery of this Agreement or the consummation of the transactions
         contemplated hereby.

         10. Expenses. Each Party shall bear its own expenses incurred in
connection with the transactions contemplated herein.

         11. Broker's Fees. Each Party represents and warrants to the other that
such Party has not incurred any liability for broker's fees, finder's fees,
agent's commissions or other similar forms of compensation in connection with or
in any way related to the transactions contemplated by this Agreement.

         12. Governing Law. This Agreement shall be governed by and construed in
accordance with the substantive law of the State of Delaware, without giving
effect to the principles of conflicts of law thereof.


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         13. Assignment; Binding Effect. Neither this Agreement nor any of the
rights, interests or obligations hereunder shall be assigned by either of the
Parties (whether by operation of law or otherwise) without the prior written
consent of the other Party. Subject to the preceding sentence, this Agreement
will be binding upon, inure to the benefit of and be enforceable by the Parties
and their respective successors and assigns.

         14. Notices. All notices, requests, demands, claims and other
communications required or permitted to be given hereunder shall be in writing
and shall be sent by (a) personal delivery (effective upon delivery), (b)
facsimile transmission (effective upon transmission), (c) recognized overnight
delivery service (effective on the next day after delivery to the delivery
service), or (d) registered or certified mail, return receipt requested and
postage prepaid (effective on the third day after being so mailed), in each case
addressed to the intended recipient as set forth below:

<TABLE>

<S>                        <C>

                  If to Prize:

                           Prize Energy Corp.
                           3500 William D. Tate
                           Suite 200
                           Grapevine, Texas  76051
                           Attention: Lon C. Kile
                           Facsimile: (817) 424-0071

                  If to Pioneer:

                           Pioneer Natural Resources USA, Inc.
                           1400 Williams Square West
                           5205 North O'Connor Blvd.
                           Irving, Texas  75039-3746
                           Attention: Mark L. Withrow
                           Facsimile No.:  (972) 969-3581
</TABLE>

Either Party may change its address for receiving notices by giving written
notice of such change to the other Party.

         15. Miscellaneous. This Agreement constitutes the entire agreement
between the Parties and supercedes any prior understandings, agreements,
arrangements and representations between the Parties, written or oral, to the
extent they related to any substantive matter hereof. This Agreement may be
executed in multiple counterparts, each of which shall be an original, but all
of which together shall constitute one and the same agreement. This Agreement
may be amended by the Parties at any time only by a written instrument signed on
behalf of each of the Parties. The waiver by either Party of a breach of any
provision hereof shall not operate or be construed as a waiver of any prior or
subsequent breach of the same or any other provision hereof.

         IN WITNESS WHEREOF, the Parties have caused this Agreement to be
executed by their duly authorized representatives as of the date first above
written.

"Prize"                                   "Pioneer"
<TABLE>
<CAPTION>

Prize Energy Corp.                        Pioneer Natural Resources USA, Inc.
<S> <C> <C>                               <C>  <C><C>
By: /s/ Lon C. Kile                       By: /s/ Mark L. Withrow
   ----------------------------------        -----------------------------------
        Lon C. Kile                               Mark L. Withrow
        President                                 Executive Vice President
</TABLE>