UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934 (Amendment No. )

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¨    Preliminary Proxy Statement

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¨    Definitive Proxy Statement

ý    Definitive Additional Materials

¨    Soliciting Material Pursuant to § 240.14a-12

Pioneer Natural Resources Company

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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PIONEER NATURAL RESOURCES COMPANY

5205 North O'Connor Boulevard

Suite 200

Irving, Texas 75039

Supplement to Definitive Proxy Statement Relating to 2018 Annual Meeting of Stockholders

This proxy statement supplement, dated May 7, 2018, supplements the definitive proxy statement (the “Proxy Statement”) of Pioneer Natural Resources Company (the “Company”) filed with the Securities and Exchange Commission on April 5, 2018 relating to the Annual Meeting of Stockholders of the Company to be held on Thursday, May 17, 2018, at 9:00 a.m. Central Time at the Midland Corporate Office located at 3617 N. Big Spring, Midland, Texas 79705.

The purpose of this supplement is to replace the charts appearing on page 35 of the Proxy Statement. The charts as filed were incorrectly labeled. The corrected charts are set out below.

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Note:   The total stockholder returns for the Company's common stock and the indices in the chart are based on closing prices as of the first and last days in the periods depicted. The total stockholder returns for the Company's common stock differ from those reported below with respect to the performance unit awards because the returns for the performance unit awards are based on average closing prices of the Company's common stock over 60-day periods prior to the first and last days in the applicable periods.

Except as specifically supplemented by the information contained herein, all information set forth in the Proxy Statement remains unchanged.