Prospectus [Rule 424(b)(3)] – Form 424B3

Filed pursuant to Rule 424(b)(3)
Registration No. 333-250888

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

On behalf of the boards of directors of Pioneer Natural Resources Company (“Pioneer”) and Parsley Energy, Inc. (“Parsley”), we are pleased to enclose the accompanying joint proxy statement/prospectus relating to the acquisition of Parsley by Pioneer. We are requesting that you take certain actions as a Pioneer or Parsley stockholder.

On October 20, 2020, Pioneer and Parsley entered into an Agreement and Plan of Merger (as amended from time to time, the “merger agreement”) with certain subsidiaries of Pioneer and Parsley, providing for (i) the merger of a direct wholly-owned subsidiary of Pioneer with and into Parsley, with Parsley surviving the merger as a direct wholly-owned subsidiary of Pioneer (the “first merger” and the surviving entity, the “surviving corporation”), (ii) simultaneously with the first merger, the merger of another direct wholly-owned subsidiary of Pioneer (“Opco Merger Sub”) with and into Parsley Energy, LLC, a majority-owned subsidiary of Parsley (“Parsley LLC”), with Parsley LLC surviving the merger as a direct and indirect wholly-owned subsidiary of Pioneer (the “Opco merger”), and (iii) immediately following the first merger and the Opco merger, the merger of the surviving corporation with and into a third direct wholly-owned subsidiary of Pioneer (“Merger Sub LLC”), with Merger Sub LLC surviving the merger as a direct wholly-owned subsidiary of Pioneer (the “subsequent merger” and, together with the first merger, the “integrated mergers” and the integrated mergers and the Opco merger, collectively, the “mergers”).

If the mergers are completed, subject to certain exceptions, each holder of Class A common stock, par value $0.01 per share, of Parsley (the “Parsley Class A common stock”) will be entitled to receive 0.1252 shares of common stock, par value $0.01 per share, of Pioneer (the “Pioneer common stock”) for each of its shares of Parsley Class A common stock and each person or entity holding units representing membership interests in Parsley LLC (each, a “Parsley LLC unit”) will be entitled to receive 0.1252 shares of Pioneer common stock for each of its Parsley LLC units, and each corresponding share of Class B common stock, par value $0.01 per share, of Parsley (the “Parsley Class B common stock” and, together with the Parsley Class A common stock, the “Parsley common stock”) will be automatically cancelled for no additional consideration, subject to any statutory rights to appraisal pursuant to the Delaware General Corporation Law solely with respect to the Parsley Class B common stock.

Following the completion of the mergers, it is anticipated that persons who were stockholders of Pioneer and Parsley immediately prior to the mergers will own approximately 76% and 24% of the combined company, respectively.

Pioneer common stock is quoted on the New York Stock Exchange (“NYSE”) under the symbol “PXD”, and Parsley Class A common stock is quoted on the NYSE under the symbol “PE”. The market prices of both Pioneer common stock and Parsley Class A common stock will fluctuate before the mergers, and you should obtain current stock price quotations for the Pioneer common stock and Parsley Class A common stock.

Your vote is very important. We cannot complete the mergers unless the Pioneer stockholders vote to approve the issuance of Pioneer common stock pursuant to the merger agreement and the Parsley stockholders vote to adopt the merger agreement.

This document is a prospectus relating to the Pioneer common stock to be issued to Parsley Class A stockholders and Parsley LLC unitholders pursuant to the mergers and a joint proxy statement for Pioneer and Parsley to solicit proxies for their respective meetings of stockholders. It contains answers to frequently asked questions and a summary of the important terms of the mergers, the merger agreement and related transactions, followed by a more detailed discussion.

Please carefully read this entire document, including “Risk Factors” beginning on page 26, for a discussion of the risks relating to the mergers and Pioneer following the mergers.

Sincerely,

Neither the Securities and Exchange Commission nor any state securities regulatory authority has approved or disapproved of the mergers or the securities to be issued under this joint proxy statement/prospectus or has passed upon the adequacy or accuracy of the disclosure in this joint proxy statement/prospectus. Any representation to the contrary is a criminal offense.

The date of the accompanying joint proxy statement/prospectus is December 4, 2020, and it is first being mailed or otherwise delivered to Pioneer stockholders and Parsley stockholders on or about December 8, 2020.

Pioneer Natural Resources Company

777 Hidden Ridge

Irving, Texas 75038

(972) 444-9001

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

TO BE HELD ON JANUARY 12, 2021

To the Stockholders of Pioneer Natural Resources Company:

You are cordially invited to attend the virtual only special meeting of the stockholders of Pioneer Natural Resources Company (“Pioneer”), which will be held at 9:00 a.m., Central Time, on January 12, 2021 via live webcast at www.virtualshareholdermeeting.com/PXD21SM (the “Pioneer special meeting”), for the following purpose:

To vote on a proposal to approve the issuance of shares of Pioneer common stock, par value $0.01 per share (“Pioneer common stock”), pursuant to the terms of the Agreement and Plan of Merger, dated as of October 20, 2020 (as amended from time to time, the “merger agreement”), by and among Pioneer, Parsley Energy, Inc. (“Parsley”) and certain subsidiaries of Pioneer and Parsley, and other shares of Pioneer common stock reserved for issuance in connection with the transactions contemplated by the merger agreement (collectively, the “stock issuance” and such proposal, the “Pioneer stock issuance proposal”).

Virtual Only Pioneer Special Meeting Due to COVID-19: In light of ongoing public health impacts related to coronavirus (COVID-19), and taking into account the related protocols that federal, state and local governments have implemented, Pioneer’s board of directors (the “Pioneer board”) has determined that the Pioneer special meeting will be a virtual meeting conducted exclusively via live webcast. There will not be a physical location for the Pioneer special meeting and you will not be able to attend the meeting in person. The Pioneer board believes that this is the right choice for Pioneer and Pioneer’s stockholders at this time, as it permits stockholders to attend the Pioneer special meeting while safeguarding the health of Pioneer stockholders, the Pioneer board and the Pioneer management team.

How to Attend the Virtual Pioneer Special Meeting: You can attend the meeting online by visiting www.virtualshareholdermeeting.com/PXD21SM, where you will be able to listen to the meeting live and vote online. To attend, vote and be deemed present in person at the virtual meeting, you will need to log on to the virtual meeting website at www.virtualshareholdermeeting.com/PXD21SM and enter the 16-digit control number included on your proxy card or voting instruction form.

The meeting webcast will begin promptly at 9:00 a.m., Central Time. We encourage you to access the meeting prior to the start time. Online check-in will begin at 8:45 a.m., Central Time, and you should allow ample time for the check-in procedures. For additional information on how you can attend the virtual Pioneer special meeting, please see the instructions beginning on page 40 of this joint proxy statement/prospectus. Whether or not you plan to attend the virtual Pioneer special meeting, we encourage you to vote and submit your proxy in advance of the meeting by one of the methods described on pages 43 and 44 of this joint proxy statement/prospectus. You may also vote online and examine our stockholder list during the Pioneer special meeting by following instructions provided on the meeting website, which may be accessed using the above web address and the 16-digit control number included on your proxy card or voting instruction form, during the Pioneer special meeting.

Meeting Agenda: Other than the Pioneer stock issuance proposal, Pioneer will transact no business at the Pioneer special meeting, except such business as may properly be brought before the Pioneer special meeting or any adjournments or postponements thereof by or at the direction of the Pioneer board in accordance with Pioneer’s bylaws. This joint proxy statement/prospectus, of which this notice is a part, describes the proposal

listed above in more detail. Please refer to the attached documents, including the merger agreement and all other annexes and any documents incorporated by reference, for further information with respect to the business to be transacted at the Pioneer special meeting. You are encouraged to read the entire document carefully before voting. In particular, please see “The Mergers” beginning on page 55 for a description of the transactions contemplated by the merger agreement, including the stock issuance, and “Risk Factors” beginning on page 26 for an explanation of the risks associated with the mergers and the other transactions contemplated by the merger agreement, including the stock issuance.

Required Vote: Approval of the Pioneer stock issuance proposal by the affirmative vote of holders of a majority of the shares of Pioneer common stock (such holders, the “Pioneer stockholders”), present virtually during the Pioneer special meeting or represented by proxy at the Pioneer special meeting and entitled to vote thereon, is required to complete the mergers, as contemplated pursuant to the merger agreement.

Who Can Vote: The Pioneer board has fixed the close of business on December 7, 2020 as the record date for the determination of the Pioneer stockholders entitled to receive notice of, and to vote at, the Pioneer special meeting or any adjournments or postponements thereof. Only Pioneer stockholders of record on the record date are entitled to receive notice of, and to vote at, the Pioneer special meeting or any adjournments or postponements thereof. For additional information regarding the Pioneer special meeting, please see “Pioneer Special Meeting” beginning on page 40 of this joint proxy statement/prospectus.

The Pioneer board, at a meeting duly called and held, has by unanimous vote (i) determined that the mergers and the other transactions contemplated by the merger agreement were in the best interests of, and were advisable to, Pioneer and the Pioneer stockholders, (ii) approved, adopted and declared advisable the merger agreement and the transactions contemplated thereby, (iii) directed that the Pioneer stock issuance be submitted to Pioneer stockholders for approval and (iv) resolved to recommend that Pioneer stockholders approve the Pioneer stock issuance at a duly held meeting of Pioneer stockholders for such purpose. The Pioneer board unanimously recommends that Pioneer stockholders vote “FOR” the Pioneer stock issuance proposal.

As a Pioneer stockholder, you play an important role in our company by considering and taking action on these matters. We appreciate the time and attention you invest in making thoughtful decisions.

YOUR VOTE IS IMPORTANT

Whether or not you plan to attend the special meeting, please submit a proxy or voting instruction card as soon as possible. For specific instructions on voting, please refer to the joint proxy statement/prospectus accompanying this notice of meeting or the proxy card included with the proxy voting materials.

If you have any questions concerning the Pioneer stock issuance proposal, the mergers or this joint proxy statement/prospectus, would like additional copies, or need help voting your shares of Pioneer common stock, please contact Pioneer’s proxy solicitor:

D.F. King & Co., Inc.

48 Wall Street, 22^nd Floor

New York, NY 10005

Banks and Brokers Call Collect: (212) 269-5550

All Others Call Toll-Free: (800) 859-8509

Email: [email protected]

Parsley Energy, Inc.

303 Colorado Street

Austin, Texas 78701

(737) 704-2300

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

TO BE HELD ON JANUARY 12, 2021

To the Stockholders of Parsley Energy, Inc.:

You are cordially invited to attend the virtual only special meeting of the stockholders of Parsley Energy, Inc. (“Parsley”), which will be held at 9:00 a.m., Central Time, on January 12, 2021 via live webcast at www.virtualshareholdermeeting.com/PE21SM (the “Parsley special meeting”), for the following purposes:

Virtual Only Parsley Special Meeting Due to COVID-19: In light of ongoing public health impacts related to coronavirus (COVID-19), and taking into account the related protocols that federal, state and local governments have implemented, Parsley’s board of directors (the “Parsley board”) has determined that the Parsley special meeting will be a virtual meeting conducted exclusively via live webcast. There will not be a physical location for the Parsley special meeting and you will not be able to attend the meeting in person. The Parsley board and Parsley’s management team believe that this is the right choice for Parsley and Parsley’s stockholders at this time, as it permits stockholders to attend the Parsley special meeting while safeguarding the health of Parsley stockholders, the Parsley board and the Parsley management team.

How to Attend the Virtual Parsley Special Meeting: You can attend the meeting online by visiting www.virtualshareholdermeeting.com/PE21SM, where you will be able to listen to the meeting live and vote online. To attend, vote and be deemed present in person at the virtual meeting, you will need to log on to the virtual meeting website at www.virtualshareholdermeeting.com/PE21SM and enter the 16-digit control number included on your proxy card or voting instruction form.

The meeting webcast will begin promptly at 9:00 a.m., Central Time. We encourage you to access the meeting prior to the start time. Online check-in will begin at 8:45 a.m., Central Time, and you should allow ample time for the check-in procedures. For additional information on how you can attend the virtual Parsley special meeting, please see the instructions beginning on page 48 of this joint proxy statement/prospectus. Whether or not you plan to attend the virtual Parsley special meeting, we encourage you to vote and submit your proxy in advance of the meeting by one of the methods described on pages 50 and 51 of this joint proxy statement/prospectus. You may also vote online and examine our stockholder list during the Parsley special meeting by following instructions provided on the meeting website, which may be accessed using the above web address and the 16-digit control number included on your proxy card or voting instruction form, during the Parsley special meeting.

Meeting Agenda: Other than the Parsley merger proposal and Parsley compensation proposal, Parsley will transact no business at the Parsley special meeting, except such business as may properly be brought before the Parsley special meeting or any adjournments or postponements thereof by or at the direction of the Parsley board in accordance with Parsley’s bylaws. This joint proxy statement/prospectus, of which this notice is a part, describes the proposals listed above in more detail. Please refer to the attached documents, including the merger agreement and all other annexes and any documents incorporated by reference, for further information with respect to the business

to be transacted at the Parsley special meeting. You are encouraged to read the entire document carefully before voting. In particular, please see “The Mergers” beginning on page 55 for a description of the transactions contemplated by the merger agreement and “Risk Factors” beginning on page 26 for an explanation of the risks associated with the mergers and the other transactions contemplated by the merger agreement.

Required Vote: Approval of the Parsley merger proposal by the affirmative vote of the holders of a majority of the outstanding shares of Parsley common stock entitled to vote on the proposal (such holders, the “Parsley stockholders”) is required to complete the mergers, as contemplated pursuant to the merger agreement. Approval of the Parsley compensation proposal requires the affirmative vote of the holders of a majority of the shares of Parsley common stock present virtually during the Parsley special meeting or represented by proxy at the Parsley special meeting and entitled to vote thereon.

Who Can Vote: The Parsley board has fixed the close of business on December 7, 2020 as the record date for the determination of the Parsley stockholders entitled to receive notice of, and to vote at, the Parsley special meeting or any adjournments or postponements thereof. Only Parsley stockholders of record on the record date are entitled to receive notice of, and to vote at, the Parsley special meeting or any adjournments or postponements thereof. For additional information regarding the Parsley special meeting, please see “Parsley Special Meeting” beginning on page 46 of this joint proxy statement/prospectus.

The Parsley board, at a meeting duly called and held, has by unanimous vote (i) declared that the merger agreement and the transactions contemplated thereby (including the integrated mergers (as defined therein)) were fair to, and in the best interests of, Parsley, the Parsley stockholders and the Parsley LLC unitholders, (ii) approved and declared advisable the merger agreement and the transactions contemplated thereby (including the integrated mergers) and (iii) recommended that the Parsley stockholders approve and adopt the merger agreement and the transactions contemplated thereby (including the integrated mergers). The Parsley board unanimously recommends that Parsley stockholders vote “FOR” the Parsley merger proposal and “FOR” the Parsley compensation proposal.

As a Parsley stockholder, you play an important role in our company by considering and taking action on these matters. We appreciate the time and attention you invest in making thoughtful decisions.

YOUR VOTE IS IMPORTANT

Whether or not you plan to attend the special meeting, please submit a proxy or voting instruction card as soon as possible. For specific instructions on voting, please refer to the joint proxy statement/prospectus accompanying this notice of meeting or the proxy card included with the proxy voting materials.

If you have any questions concerning the Parsley merger proposal, the Parsley compensation proposal, the mergers or this joint proxy statement/prospectus, would like additional copies, or need help voting your shares of Parsley common stock, please contact Parsley’s proxy solicitor:

MacKenzie Partners, Inc.

1407 Broadway, 27^th Floor

New York, NY 10018

Banks and Brokers Call Collect: (212) 929-5500

All Others Call Toll-Free: (800) 322-2885

Email: [email protected]

ADDITIONAL INFORMATION

Both Pioneer and Parsley file annual, quarterly and current reports, proxy statements, and other business and financial information with the Securities and Exchange Commission (the “SEC”) electronically, and the SEC maintains a website located at www.sec.gov containing this information. You can also obtain these documents, free of charge, from Pioneer at www.pxd.com and from Parsley at www.parsleyenergy.com, as applicable. The information contained on, or that may be accessed through, Pioneer’s and Parsley’s websites is not incorporated by reference into, and is not a part of, this joint proxy statement/prospectus.

Pioneer has filed a registration statement on Form S-4 with respect to the shares of Pioneer common stock to be issued in the mergers or reserved for issuance in connection with the mergers, of which this joint proxy statement/prospectus forms a part. This joint proxy statement/prospectus constitutes the prospectus of Pioneer filed as part of the registration statement. As permitted by SEC rules, this joint proxy statement/prospectus does not contain all of the information included in the registration statement or in the exhibits or schedules to the registration statement. You may read and copy the registration statement, including any amendments, schedules, and exhibits, at the SEC’s website mentioned above. Statements contained in this joint proxy statement/prospectus as to the contents of any contract or other documents referred to in this joint proxy statement/prospectus are not necessarily complete. In each case, you should refer to the copy of the applicable agreement or other document filed as an exhibit to the registration statement.

This joint proxy statement/prospectus incorporates important business and financial information about Pioneer and Parsley from documents that are not attached to this joint proxy statement/prospectus. This information is available to you without charge upon your request. You can obtain the documents incorporated by reference into this joint proxy statement/prospectus, including copies of financial statements and management’s discussion and analysis, free of charge by requesting them in writing or by telephone from the appropriate company or its proxy solicitor at the following addresses and telephone numbers:

If you would like to request any documents, please do so by January 5, 2021, which is five business days prior to the date of the Pioneer special meeting and the Parsley special meeting, in order to receive them before the applicable meeting.

For a more detailed description of the information incorporated by reference into this joint proxy statement/prospectus and how you may obtain it, please see “Where You Can Find More Information.”

ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS

This joint proxy statement/prospectus, which forms part of the registration statement on Form S-4 filed with the SEC by Pioneer, constitutes a prospectus of Pioneer under the Securities Act of 1933, as amended (the “Securities Act”), with respect to the shares of Pioneer common stock issuable to Parsley Class A stockholders and Parsley LLC unitholders in connection with the mergers. This joint proxy statement/prospectus also constitutes a joint proxy statement for both Pioneer and Parsley under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). This joint proxy statement/prospectus also constitutes a notice of meeting with respect to the Pioneer special meeting and a notice of meeting with respect to the Parsley special meeting.

You should rely only on the information contained in or incorporated by reference into this joint proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated December 4, 2020, and you should assume that the information contained in this joint proxy statement/prospectus is accurate only as of such date. You should also assume that the information incorporated by reference into this joint proxy statement/prospectus is only accurate as of the date of such information. Neither the mailing of this joint proxy statement/prospectus to Pioneer stockholders or Parsley stockholders nor the issuance by Pioneer of shares of Pioneer common stock pursuant to the merger agreement will create any implication to the contrary.

This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction. Information contained in this joint proxy statement/prospectus regarding Pioneer has been provided by Pioneer, and information contained in this joint proxy statement/prospectus regarding Parsley has been provided by Parsley.

GLOSSARY

The following terms have the following meanings in this joint proxy statement/prospectus:

All currency amounts referenced in this joint proxy statement/prospectus are in U.S. dollars.

TABLE OF CONTENTS

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QUESTIONS AND ANSWERS ABOUT THE MEETINGS

The following are some questions that you may have regarding the mergers, the issuance of shares of Pioneer common stock to Parsley Class A stockholders and Parsley LLC unitholders in connection with the mergers, and other matters being considered at the Parsley special meeting and the answers to those questions. Pioneer and Parsley urge you to carefully read the entirety of this joint proxy statement/prospectus, including the annexes hereto and the information incorporated by reference herein, because the information in this section does not provide all the information that might be important to you with respect to the mergers, the issuance of shares of Pioneer common stock in connection with the mergers, and the other matters being considered at the Parsley special meeting.

In order to complete the mergers, and in accordance with the rules of the New York Stock Exchange (the “NYSE”), Pioneer stockholders must approve the issuance of shares of Pioneer common stock in the mergers and other shares of Pioneer common stock reserved for issuance in connection with the mergers, in each case pursuant to the terms of the merger agreement (the “stock issuance” and such proposal, the “Pioneer stock issuance proposal”). Approval of the Pioneer stock issuance proposal requires the affirmative vote of holders of a majority of the shares of Pioneer common stock present virtually during the Pioneer special meeting or represented by proxy at the Pioneer special meeting and entitled to vote thereon.

Also, in order to complete the mergers, and in accordance with the Delaware General Corporation Law (the “DGCL”), Parsley stockholders must approve and adopt the merger agreement and the transactions contemplated thereby (including the integrated mergers) (the “Parsley merger proposal”). Approval of the Parsley merger proposal requires the affirmative vote of the holders of a majority of the outstanding shares of Parsley common stock entitled to vote on the proposal. In addition, Parsley’s stockholders will be asked to approve, on a non-binding advisory basis, the compensation that may be paid or become payable to Parsley’s named executive officers (“NEOs”) that is based on or otherwise relates to the mergers (the “Parsley compensation proposal”). Approval of the Parsley compensation proposal requires the affirmative vote of the holders of a majority of the shares of Parsley common stock present virtually during the Parsley special meeting or represented by proxy at the Parsley special meeting and entitled to vote thereon.

This joint proxy statement/prospectus, which you should read carefully, contains important information about the mergers, the stock issuance and other matters being considered at the Pioneer special meeting and the Parsley special meeting.

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In addition, Parsley and Pioneer will take, or cause to be taken, all actions necessary so that, at the effective time, Parsley’s issued and outstanding time-based restricted stock unit awards, performance-based restricted stock unit awards, time-based restricted stock awards and performance-based restricted stock awards will be treated as described in “The Merger Agreement—Treatment of Parsley Equity-Based Awards.”

For additional information regarding the consideration to be received in the mergers, please see “The Merger Agreement—Terms of the Mergers; Merger Consideration.”

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The merger consideration received by Parsley LLC unitholders and the cancellation of the Parsley Class B common stock will be subject to certain tax treatment as described in “The Mergers—Material U.S. Federal Income Tax Consequences.”

For additional information regarding the consideration to be received in the mergers, please see “The Merger Agreement—Terms of the Mergers; Merger Consideration.”

If you are a holder of book-entry shares representing eligible shares of Parsley Class A common stock (“Parsley Class A book-entry shares”), the exchange agent will send you, as promptly as practicable (and in any event, within three business days) after the effective time, the merger consideration, cash in lieu of any fractional shares of Pioneer common stock and any dividends and other distributions on the shares of Pioneer common stock issuable as merger consideration, in each case, that such holder has the right to receive.

No interest will be paid or accrued on any amount payable for shares of Parsley Class A common stock or Parsley LLC units eligible to receive the merger consideration pursuant to the merger agreement.

For additional information on the exchange of Parsley Class A common stock and Parsley LLC units for the merger consideration (and on the corresponding cancellation of Parsley Class B common stock for no additional consideration), please see “The Merger Agreement—Exchange and Payment Procedures.”

Parsley Time-Based Restricted Stock Unit Awards: Each vested Parsley time-based restricted stock unit award (including any Parsley time-based restricted stock unit award that vests by its terms as a result of the consummation of the mergers) that is issued and outstanding as of immediately prior to the effective time will, at the effective time, be cancelled and converted into the right to receive a number of shares of Pioneer common stock (to be issued within 30 days following the closing date in accordance with the terms of the applicable restricted stock unit award agreement), rounded up or down to the nearest whole share, equal to the product of (a) the number of shares of Parsley Class A common stock subject to such award as of immediately prior to the effective time and (b) the exchange ratio. Any Parsley time-based restricted stock unit award held by a non-employee member of the Parsley board will become fully vested as a result of the consummation of the mergers and will be treated as a vested Parsley time-based restricted stock unit award entitled to the foregoing treatment. Each unvested Parsley time-based restricted stock unit award (excluding any Parsley time-based restricted stock unit award that vests by its terms as a result of the consummation of the mergers) that is issued and outstanding as of immediately prior to the effective time will, at the effective

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time, be converted, on the same terms and conditions (including time-based vesting conditions) as were applicable to such award as of immediately prior to the effective time, into the right to receive a time-based award covering a number of shares of Pioneer common stock, rounded up or down to the nearest whole share, equal to the product of (a) the number of shares of Parsley Class A common stock subject to such award as of immediately prior to the effective time and (b) the exchange ratio.

Parsley Time-Based Restricted Stock Awards: Each unvested Parsley time-based restricted stock award (excluding any Parsley time-based restricted stock award that vests by its terms as a result of the consummation of the mergers) that is issued and outstanding as of immediately prior to the effective time will, at the effective time, be converted, on the same terms and conditions (including time-based vesting conditions) as were applicable to such time-based restricted stock award as of immediately prior to the effective time, into the right to receive a time-based restricted stock award of Pioneer covering a number of shares of Pioneer common stock, rounded up or down to the nearest whole share, equal to the product of (a) the number of shares of Parsley Class A common stock subject to such award as of immediately prior to the effective time and (b) the exchange ratio.

Parsley Performance-Based Restricted Stock Unit Awards and Performance-Based Restricted Stock Awards: Each Parsley performance-based restricted stock unit award and Parsley performance-based restricted stock award that is issued and outstanding as of immediately prior to the effective time will be deemed to have become vested pursuant to the terms of the merger agreement based on deemed achievement of the maximum level of performance applicable to such award as of the date immediately prior to the effective time. At the effective time, any such vested performance-based restricted stock unit award will automatically be cancelled and converted into the right to receive a number of shares of Pioneer common stock (to be issued within 30 days following the closing date in accordance with the terms of the applicable award agreement), rounded up or down to the nearest whole share, equal to the product of (a) the number of shares of Parsley Class A common stock subject to such award as of immediately prior to the effective time and (b) the exchange ratio. At the effective time, any such vested performance-based restricted stock award will automatically be converted into the right to receive a number of shares of Pioneer common stock, rounded up or down to the nearest whole share, equal to the product of (a) the number of shares of Parsley Class A common stock subject to such award as of immediately prior to the effective time and (b) the exchange ratio.

For additional information regarding the treatment of Parsley equity awards, please see “The Merger Agreement—Treatment of Parsley Equity-Based Awards.”

Additionally, pursuant to the merger agreement, Pioneer and Parsley have agreed that the Pioneer board will be expanded by two members as of the effective time and Matt Gallagher and A.R. Alameddine will be

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appointed as directors of the Pioneer board. If either Mr. Gallagher and/or Mr. Alameddine is unwilling or unable to serve as a member of the Pioneer board at the effective time, then another member or members of the Parsley board that is determined by the Pioneer board in good faith to be independent with respect to his or her service on the Pioneer board and is mutually agreed between Pioneer and Parsley will instead be appointed to fill such vacancy or vacancies on the Pioneer board in lieu of Mr. Gallagher and/or Mr. Alameddine, as applicable. Any remuneration to be paid to these directors will be consistent with Pioneer’s remuneration policy for its directors. Pioneer has also agreed to take all action necessary to nominate the Parsley director designees for election to the Pioneer board in the proxy statement relating to the first annual meeting of Pioneer stockholders following the closing of the mergers. In addition, the Pioneer board (or a committee thereof) will appoint each Parsley director designee to a committee of the Pioneer board within 90 days following the closing date, in a manner consistent with its ordinary policies and practices. For additional information, please see “The Mergers—Board of Directors and Management of Pioneer Following Completion of the Mergers.”

Pioneer. Approval of the Pioneer stock issuance proposal requires the affirmative vote of holders of a majority of the shares of Pioneer common stock present virtually during the Pioneer special meeting or represented by proxy at the Pioneer special meeting and entitled to vote thereon. Accordingly, a Pioneer stockholder’s abstention from voting will have the same effect as a vote “against” the Pioneer stock issuance proposal, while a broker non-vote or the failure of a Pioneer stockholder to attend the Pioneer special meeting, virtually or by proxy, and vote will have no effect on the outcome of the Pioneer stock issuance proposal.

Parsley. Approval of the Parsley merger proposal requires the affirmative vote of the holders of a majority of the outstanding shares of Parsley common stock entitled to vote on the proposal. Accordingly, a Parsley stockholder’s abstention from voting, a broker non-vote, or the failure of a Parsley stockholder to attend the Parsley special meeting, virtually or by proxy, and vote will have the same effect as a vote “against” the Parsley merger proposal. Approval of the Parsley compensation proposal requires the affirmative vote of the holders of a majority of the shares of Parsley common stock present virtually during the Parsley special meeting or represented by proxy at the Parsley special meeting and entitled to vote thereon. Accordingly, a Parsley stockholder’s abstention from voting will have the same effect as a vote “against” the Parsley compensation proposal, while a broker non-vote or the failure of a Parsley stockholder to attend the Parsley special meeting, virtually or by proxy, and vote will have no effect on the outcome of the Parsley compensation proposal.

The Parsley board unanimously recommends that Parsley stockholders vote “FOR” the Parsley merger proposal and “FOR” the Parsley compensation proposal. For additional information regarding how the Parsley board recommends that Parsley stockholders vote, see the section titled “The Mergers—Recommendation of the Parsley Board and Reasons for the Mergers.”

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After the closing of the mergers, former Parsley Class A stockholders and Parsley LLC unitholders who hold Parsley Class A common stock certificates or Parsley LLC unit certificates, or who otherwise hold eligible Parsley LLC units, as applicable, will not be entitled to be paid dividends otherwise payable on the shares of Pioneer common stock into which their shares of Parsley Class A common stock or Parsley LLC units are exchangeable until they surrender their Parsley Class A common stock certificates or Parsley LLC unit certificates, as applicable, and deliver an applicable letter of transmittal. Dividends will be accrued for these holders and they will receive the accrued dividends, without interest, when they surrender their Parsley Class A common stock certificates or Parsley LLC unit certificates, as applicable, and deliver an applicable letter of transmittal.

Parsley has declared a fourth quarter cash dividend of $0.05 per share of Parsley Class A common stock, payable on December 18, 2020 to holders of record on December 8, 2020. Pioneer has declared a quarterly dividend of $0.55 per share of Pioneer common stock, payable on January 14, 2021 to holders of record on December 31, 2020. After the closing of the mergers, all Pioneer dividends will remain subject to approval by the Pioneer board.

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Please see “The Mergers—Material U.S. Federal Income Tax Consequences” for a more detailed discussion of the U.S. federal income tax consequences of the integrated mergers to U.S. holders of Parsley Class A common stock. Each Parsley Class A stockholder is strongly urged to consult with a tax advisor to determine the particular U.S. federal, state or local or non-U.S. income or other tax consequences of the integrated mergers to it.

Please see “The Mergers—Material U.S. Federal Income Tax Consequences” for a more detailed discussion of the U.S. federal income tax consequences of the Opco merger to U.S. holders of Parsley LLC units. Each Parsley LLC unitholder is strongly urged to consult with a tax advisor to determine the particular U.S. federal, state or local or non-U.S. income or other tax consequences of the Opco merger to it.

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Under specified circumstances, Pioneer or Parsley may be required to reimburse the other party’s expenses or pay a termination fee upon or subsequent to termination of the merger agreement, as described in “The Merger Agreement—Termination Fees and Expense Reimbursement.”

All Parsley stockholders who hold shares of Parsley common stock of record at the close of business on December 7, 2020, the record date for the Parsley special meeting (the “Parsley record date”), are entitled to receive notice of and to vote at the Parsley special meeting.

Each issued and outstanding share of Parsley Class A common stock and each issued and outstanding share of Parsley Class B common stock entitles its holder of record to one vote on each matter to be considered at the Parsley special meeting, and the Parsley Class A common stock and Parsley Class B common stock will vote together as a single class. The Parsley stockholders of record on the Parsley record date are the only Parsley stockholders that are entitled to receive notice of, and to vote at, the Parsley special meeting or any adjournments or postponements thereof.

A quorum at the Pioneer special meeting requires the presence of the holders of a majority of the total issued and outstanding shares of Pioneer common stock entitled to vote, present virtually or represented by proxy, at the Pioneer special meeting. A Pioneer stockholder will be considered present at the virtual meeting by logging into the Pioneer special meeting website using his, her or its unique 16-digit control number or by appointing a proxy. If you submit a properly executed proxy card, or submit a proxy via the internet or by telephone, even if you do not vote for the proposal or vote to “abstain” in respect of the proposal, your shares of Pioneer common stock will be counted for purposes of calculating whether a quorum is present for the transaction of business at the Pioneer special meeting. Because it is expected that the only matter to be voted on at the Pioneer special meeting will be non-routine under NYSE rules, brokers will not have discretionary authority to vote on the Pioneer stock issuance proposal; therefore, if you do not provide voting instructions to your broker, bank or other nominee, your shares will not count towards determining whether a quorum is present and your shares will not be voted on the Pioneer stock issuance proposal.

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A quorum at the Parsley special meeting requires the presence of the holders of a majority of the total issued and outstanding shares of Parsley common stock entitled to vote, present virtually or represented by proxy, at the Parsley special meeting. A Parsley stockholder will be considered present at the virtual meeting by logging into the Parsley special meeting website using his, her or its unique 16-digit control number or by appointing a proxy. If you submit a properly executed proxy card, or submit a proxy via the internet or by telephone, even if you do not vote for the proposal or vote to “abstain” in respect of the proposal, your shares of Parsley common stock will be counted for purposes of calculating whether a quorum is present for the transaction of business at the Parsley special meeting. Because it is expected that all of the matters to be voted on at the Parsley special meeting will be non-routine under NYSE rules, brokers will not have discretionary authority to vote on any such proposal; therefore, if you do not provide voting instructions to your broker, bank or other nominee, your shares will not count towards determining whether a quorum is present and your shares will not be voted on the Parsley merger proposal or the Parsley compensation proposal.

For additional information on voting procedures, please see “Pioneer Special Meeting” and “Parsley Special Meeting.”

For additional information on voting procedures, please see “Pioneer Special Meeting” and “Parsley Special Meeting.”

The votes at the Parsley special meeting will be tabulated and certified by the inspector of elections appointed by the Parsley board.

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If your shares of Pioneer common stock or Parsley common stock are held through a bank, broker or other nominee, you are considered, with respect to those shares, the beneficial owner, and those shares are held in “street name” by your bank, broker or other nominee. In that case, this joint proxy statement/prospectus has been forwarded to you by your bank, broker or other nominee. As the beneficial owner, you have the right to direct your bank, broker or other nominee how to vote your shares by following their instructions for voting, and you are also invited to attend the Pioneer special meeting or the Parsley special meeting, as applicable. The proxy materials you received include the 16-digit control number that you will need to vote online during the Pioneer special meeting or the Parsley special meeting, as applicable.

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You should instruct your bank, broker or other nominee how to vote your shares of Pioneer common stock or Parsley common stock, as applicable. Under the rules applicable to broker-dealers, your bank, broker or other nominee does not have discretionary authority to vote your shares on any of the proposals scheduled to be voted on at the Pioneer special meeting or the Parsley special meeting. A so-called “broker non-vote” results when banks, brokers and other nominees return a valid proxy but do not vote on a particular proposal because they do not have discretionary authority to vote on the matter and have not received specific voting instructions from the beneficial owner of such shares. Pioneer and Parsley do not expect any broker non-votes at the Pioneer special meeting or the Parsley special meeting because the rules applicable to banks, brokers and other nominees only provide brokers with discretionary authority to vote on proposals that are considered routine, whereas each of the proposals to be presented at the Pioneer special meeting and the Parsley special meeting are considered non-routine under NYSE rules. As a result, no broker will be permitted to vote your shares of Pioneer common stock or Parsley common stock at the applicable special meeting without receiving instructions. Failure to instruct your broker on how to vote your shares will have (i) no effect on the Pioneer stock issuance proposal, for Pioneer stockholders, and (ii) the same effect as a vote “against” the Parsley merger proposal and no effect on the Parsley compensation proposal, for Parsley stockholders.

For additional information on voting procedures, please see “Pioneer Special Meeting” and “Parsley Special Meeting.”

All Pioneer stockholders may also revoke their proxies by attending the Pioneer special meeting virtually, using his, her or its unique 16-digit control number and voting their shares online during the meeting. Note that attendance at the virtual Pioneer special meeting will not, in and of itself, revoke a valid proxy that was previously delivered unless you give written notice of revocation to the Pioneer corporate secretary before the proxy is exercised or unless you vote your shares online during the Pioneer special meeting.

If a Pioneer stockholder holds shares through a bank, broker or other nominee, such stockholder may change or revoke his, her or its voting instructions before the Pioneer special meeting by providing instructions again through the means specified on his, her or its voting instruction form (with most having the option to do so by internet, telephone or mail), which must be received before 10:59 p.m. Central Time on January 11, 2021.

For additional information, please see “Pioneer Special Meeting.”

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All Parsley stockholders may also revoke their proxies by attending the Parsley special meeting virtually, using his, her or its unique 16-digit control number and voting their shares online during the meeting. Note that attendance at the virtual Parsley special meeting will not, in and of itself, revoke a valid proxy that was previously delivered unless you give written notice of revocation to the Parsley corporate secretary before the proxy is exercised or unless you vote your shares online during the Parsley special meeting.

If a Parsley stockholder holds shares through a bank, broker or other nominee, such stockholder may change or revoke his, her or its voting instructions before the Parsley special meeting by providing instructions again through the means specified on his, her or its voting instruction form (with most having the option to do so by internet, telephone or mail), which must be received before 10:59 p.m. Central Time on January 11, 2021.

For additional information, please see “Parsley Special Meeting.”

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For more information on these interests and quantification of certain of these interests, please see “The Mergers—Interests of Certain Parsley Directors and Executive Officers in the Mergers.”

Because shares of Parsley Class A common stock are listed on the NYSE and holders of eligible shares of Parsley Class A common stock are not required to receive consideration other than shares of Pioneer common stock, which are listed on the NYSE, and any cash received in lieu of fractional shares of Pioneer common stock in the mergers, Parsley Class A stockholders are not entitled to exercise dissenters’ or appraisal rights under Delaware law in connection with the mergers. However, Parsley Class B stockholders who do not vote in favor of the Parsley merger proposal will be entitled to exercise appraisal rights under the DGCL, solely with respect to their shares of Parsley Class B common stock (and not, for the avoidance of doubt, with respect to any shares of Parsley Class A common stock or Parsley LLC units held by them), in connection with the mergers if they take certain actions and meet certain conditions set forth in Section 262 of the DGCL (“Section 262”). Failure to comply with Section 262 may result in a Parsley Class B stockholder waiving, or being unable to exercise, appraisal rights. Parsley stockholders may vote against the Parsley merger proposal if they do not favor the mergers.

For more information regarding appraisal rights, please see “The Mergers—Appraisal Rights or Dissenters’ Rights”. In addition, a copy of Section 262 is attached as Annex F to this joint proxy statement/prospectus.

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RISK FACTORS

In addition to the other information included or incorporated by reference in this joint proxy statement/prospectus, including the matters addressed in “Cautionary Statement Regarding Forward-Looking Statements”, you should carefully consider the following risks before deciding how to vote. In addition, you should read and carefully consider the risks associated with each of Pioneer and Parsley and their respective businesses. These risks can be found in Pioneer’s and Parsley’s Annual Reports on Form 10-K for the year ended December 31, 2019 and subsequent Quarterly Reports on Form 10-Q, each of which is filed with the SEC and incorporated by reference into this joint proxy statement/prospectus. For further information regarding the documents incorporated into this joint proxy statement/prospectus by reference, please see the section titled “Where You Can Find More Information.” Realization of any of the risks described below, any of the events described under “Cautionary Statement Regarding Forward-Looking Statements” or any of the risks or events described in the documents incorporated by reference could have a material adverse effect on Pioneer’s, Parsley’s or the combined company’s businesses, financial condition, cash flows and results of operations.

Risks Relating to the Mergers

Because the market price of Pioneer common stock will fluctuate, Parsley Class A stockholders and Parsley LLC unitholders cannot be sure of the value of the shares of Pioneer common stock they will receive in connection with the mergers. In addition, because the exchange ratio is fixed, the number of shares of Pioneer common stock to be received by Parsley Class A stockholders and Parsley LLC unitholders in connection with the mergers will not change between now and the time the mergers are completed to reflect changes in the trading prices of Pioneer common stock or Parsley Class A common stock.

In connection with the mergers, each eligible share of Parsley Class A common stock and each eligible Parsley LLC unit will be converted automatically into the right to receive 0.1252 shares of Pioneer common stock, with cash paid in lieu of the issuance of any fractional shares of Pioneer common stock. The exchange ratio is fixed, which means that it will not change between now and the closing date, regardless of whether the market price of either Pioneer common stock or Parsley Class A common stock changes. Therefore, the value of the merger consideration will depend on the market price of Pioneer common stock at the effective time. The market price of Pioneer common stock has fluctuated since the date of the announcement of the parties’ entry into the merger agreement and will continue to fluctuate from the date of this joint proxy statement/prospectus to the date of the Parsley special meeting and the Pioneer special meeting, the date the mergers are completed and thereafter. The market price of Pioneer common stock, when received by Parsley Class A stockholders and Parsley LLC unitholders after the mergers are completed, could be greater than, less than or the same as the market price of Pioneer common stock on the date of this joint proxy statement/prospectus or at the time of the Parsley special meeting. Accordingly, you should obtain current stock price quotations for Pioneer common stock and Parsley Class A common stock before deciding how to vote or abstain from voting on any of the proposals described in this joint proxy statement/prospectus.

The market price for Pioneer common stock following the closing may be affected by factors different from those that historically have affected or currently affect Pioneer common stock and Parsley Class A common stock.

Upon completion of the mergers, Parsley Class A stockholders and Parsley LLC unitholders will receive shares of Pioneer common stock. Pioneer’s financial position may differ from its financial position before the completion of the mergers, and the results of operations of the combined company may be affected by some factors that are different from those currently affecting the results of operations of Pioneer and those currently affecting the results of operations of Parsley. Accordingly, the market price and performance of Pioneer common stock is likely to be different from the performance of Parsley Class A common stock in the absence of the mergers. In addition, general fluctuations in stock markets could have a material adverse effect on the market for, or liquidity of, Pioneer common stock, regardless of Pioneer’s actual operating performance. For a discussion of

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the businesses of Pioneer and Parsley and important factors to consider in connection with those businesses, see the documents incorporated by reference herein and referred to in “Where You Can Find More Information.”

Pioneer stockholders and Parsley stockholders, in each case as of immediately prior to the mergers, will have reduced ownership in the combined company.

Based on the number of issued and outstanding shares of Parsley Class A common stock and Parsley LLC units as of November 30, 2020 and the number of issued and outstanding Parsley equity awards currently estimated to be payable in shares of Pioneer common stock in connection with the mergers, Pioneer anticipates issuing approximately 52 million shares of Pioneer common stock pursuant to the merger agreement. The actual number of shares of Pioneer common stock to be issued pursuant to the merger agreement will be determined at the completion of the mergers based on the number of shares of Parsley Class A common stock and Parsley LLC units issued and outstanding immediately prior to such time and the number of issued and outstanding Parsley equity awards payable in shares of Pioneer common stock in connection with the mergers. The issuance of these new shares could have the effect of depressing the market price of Pioneer common stock, through dilution of earnings per share or otherwise. Any dilution of, or delay of any accretion to, Pioneer’s earnings per share could cause the price of Pioneer common stock to decline or increase at a reduced rate.

Immediately after the completion of the mergers, it is expected that Pioneer stockholders as of immediately prior to the mergers will own approximately 76%, and Parsley stockholders as of immediately prior to the mergers will own approximately 24%, of the issued and outstanding shares of Pioneer common stock. As a result, Pioneer’s current stockholders and Parsley’s current stockholders will have less influence on the policies of the combined company than they currently have on the policies of Pioneer and Parsley, respectively.

Pioneer and Parsley must obtain certain regulatory approvals and clearances to consummate the mergers, which, if delayed, not granted or granted with unacceptable conditions, could prevent, substantially delay or impair consummation of the mergers, result in additional expenditures of money and resources or reduce the anticipated benefits of the mergers.

The completion of the mergers is subject to antitrust review in the United States. Under the HSR Act and the rules promulgated thereunder, the mergers cannot be completed until the parties to the merger agreement have given notification and furnished information to the FTC and the DOJ, and until the applicable waiting period has expired or has been terminated.

On November 12, 2020, Pioneer and Parsley received notice of early termination of the applicable waiting period under the HSR Act.

At any time before or after consummation of the mergers, notwithstanding the early termination of the applicable waiting period under the HSR Act, the FTC, the DOJ or any state could take such action under antitrust laws as it deems necessary or desirable in the public interest, including seeking to enjoin the completion of the mergers or seeking the divestiture of substantial assets of Pioneer or Parsley or their respective subsidiaries. Private parties may also seek to take legal action under antitrust laws under certain circumstances.

The mergers are subject to a number of conditions to the obligations of both Pioneer and Parsley to complete the mergers, which, if not fulfilled, or not fulfilled in a timely manner, may delay completion of the mergers or result in termination of the merger agreement.

The respective obligations of each of Parsley and Pioneer to effect the mergers are subject to the satisfaction at or prior to the effective time of the following conditions:

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Many of the conditions to completion of the mergers are not within either Pioneer’s or Parsley’s control, and neither company can predict when, or if, these conditions will be satisfied. If any of these conditions are not satisfied or waived prior to the outside date, it is possible that the merger agreement may be terminated. Although Pioneer and Parsley have agreed in the merger agreement to use reasonable best efforts, subject to certain limitations, to complete the mergers as promptly as practicable, these and other conditions to the completion of the mergers may fail to be satisfied. In addition, satisfying the conditions to and completing the mergers may take longer, and could cost more, than Pioneer and Parsley expect. Neither Pioneer nor Parsley can predict whether and when these other conditions will be satisfied. Furthermore, the requirements for obtaining the required clearances and approvals could delay the completion of the mergers for a significant period of time or prevent them from occurring. Any delay in completing the mergers may adversely affect the cost savings and other benefits that Pioneer and Parsley expect to achieve if the mergers and the integration of the companies’ respective businesses are completed within the expected timeframe. There can be no assurance that all required regulatory approvals will be obtained or obtained prior to the termination date. For additional information, please see “The Merger Agreement—Conditions Precedent to the Mergers.”

If the integrated mergers, taken together, do not qualify as a “reorganization” within the meaning of Section 368(a) of the Code, Parsley Class A stockholders may be required to pay substantial U.S. federal income taxes.

The integrated mergers are intended to qualify as a “reorganization” within the meaning of Section 368(a) of the Code, and Pioneer and Parsley intend to report the integrated mergers consistent with such qualification. It is a condition to Parsley’s obligation to complete the mergers that it receive an opinion from its tax counsel to the effect that the integrated mergers, taken together, will qualify as a “reorganization” within the meaning of Section 368(a) of the Code. This opinion will be based on customary assumptions and representations from each of Pioneer and Parsley, as well as certain covenants and undertakings by Pioneer and Parsley. If any of the representations, assumptions, covenants or undertakings upon which the opinion is based is or becomes incorrect, incomplete or inaccurate or is violated, the validity of the opinion may be affected and the U.S. federal income tax consequences of the integrated mergers could differ materially from those described herein. An opinion of counsel represents such counsel’s best legal judgment but is not binding on the Internal Revenue Service (the “IRS”) or any court. Neither Pioneer nor Parsley intends to obtain a ruling from the IRS with respect to the tax

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consequences of the integrated mergers. Accordingly, there can be no assurance that the IRS would not challenge the conclusions reflected in the opinion or that a court would not sustain such a challenge. If the IRS or a court determines that the integrated mergers, taken together, should not be treated as a “reorganization” within the meaning of Section 368(a) of the Code, a U.S. holder of Parsley Class A common stock would generally recognize taxable gain or loss upon the exchange of Parsley Class A common stock for Pioneer common stock pursuant to the integrated mergers. See “The Mergers—Material U.S. Federal Income Tax Consequences”.

The Opco merger is expected to be a taxable event for Parsley LLC unitholders, and the resulting tax liability, if any, of a Parsley LLC unitholder will depend on such unitholder’s particular situation. Additionally, the amount and character of any taxable gain or loss recognized by a Parsley LLC unitholder as a result of the Opco merger could be different than anticipated, potentially resulting in a tax liability that is more than expected.

The exchange of Parsley LLC units for shares of Pioneer common stock (and cash in lieu of fractional shares of Pioneer common stock, if any) in the Opco merger is intended to be a taxable event for Parsley LLC unitholders, even though Parsley LLC unitholders will receive no cash consideration (other than any cash received in lieu of fractional shares of Pioneer common stock) in the Opco merger. The amount and character of gain or loss recognized by each Parsley LLC unitholder as a result of such taxable exchange will vary depending on such unitholder’s particular situation, including the value of the Pioneer common stock received by such unitholder, whether such unitholder receives any cash in lieu of fractional shares of Pioneer common stock in the Opco merger or a TRA termination payment, and the adjusted tax basis of such unitholder’s Parsley LLC units (and any changes to such tax basis as a result of Parsley LLC’s allocations of income, gain, loss and deduction to such unitholder for the taxable year that includes the Opco merger). Moreover, Parsley LLC unitholders that are subject to the passive loss rules may have suspended passive losses that may become available to offset a portion of the gain recognized by such Parsley LLC unitholder in connection with the Opco merger.

Because, among other things, a Parsley LLC unitholder will not know, until the effective time of the Opco merger, the value of the shares of Pioneer common stock it will receive in the Opco merger, a Parsley LLC unitholder will not be able to calculate the amount of its taxable gain or loss until such time using the information available to such unitholder at that time and will not be able to finally determine its taxable gain or loss until it receives its Schedule K-1 for the year in which the Opco merger is consummated. In addition, because prior distributions in excess of a Parsley LLC unitholder’s allocable share of Parsley LLC’s net taxable income decrease such Parsley LLC unitholder’s tax basis in its Parsley LLC units, the amount, if any, of such prior excess distributions with respect to such Parsley LLC units will, in effect, become taxable income to a Parsley LLC unitholder if the aggregate value of the consideration received (or treated for tax purposes as received) in the Opco merger is greater than such Parsley LLC unitholder’s adjusted tax basis in its Parsley LLC units, even if the aggregate value of the consideration received (or treated for tax purposes as received) in the Opco merger is less than such Parsley LLC unitholder’s original cost basis in its Parsley LLC units. Furthermore, a portion of this gain or loss, which portion could be substantial, will be separately computed and taxed as ordinary income or loss to the extent attributable to assets giving rise to depreciation recapture or other “unrealized receivables” or to “inventory items” owned by Parsley LLC and its subsidiaries. For additional information, please see “The Mergers—Material U.S. Federal Income Tax Consequences”.

The U.S. federal income tax treatment to Parsley LLC unitholders with respect to owning and disposing of any shares of Pioneer common stock received in the Opco merger will be different than the U.S. federal income tax treatment to them with respect to owning and disposing of their Parsley LLC units.

Parsley LLC is classified as a partnership for U.S. federal income tax purposes and is not generally subject to entity-level U.S. federal income tax. Instead, each Parsley LLC unitholder is required to take into account such unitholder’s share of items of income, gain, loss, and deduction of Parsley LLC in computing its U.S. federal income tax liability, regardless of whether cash distributions are made to such Parsley LLC unitholder by Parsley

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LLC. A distribution of cash by Parsley LLC to a Parsley LLC unitholder who is a U.S. holder (as defined in the section titled “The Mergers—Material U.S. Federal Income Tax Consequences”) is generally not taxable for U.S. federal income tax purposes unless the amount of cash distributed is in excess of the Parsley LLC unitholder’s adjusted tax basis in its Parsley LLC units. Gain or loss recognized by a Parsley LLC unitholder who is a U.S. holder in connection with the disposition of its Parsley LLC units will generally be capital gain or loss. However, a portion of such gain or loss, which portion could be substantial, is separately computed and taxed as ordinary income or loss under Section 751 of the Code to the extent attributable to assets giving rise to depreciation recapture or other “unrealized receivables” or to “inventory items” owned by Parsley LLC and its subsidiaries. Consequently, a Parsley LLC unitholder may recognize both ordinary income and capital loss in connection with a disposition of its Parsley LLC units.

In contrast, Pioneer is classified as a corporation for U.S. federal income tax purposes, and thus, Pioneer (and not its stockholders) is subject to U.S. federal income tax on its taxable income. A distribution of cash with respect to Pioneer common stock by Pioneer to a stockholder who is a U.S. holder will generally be included in such U.S. holder’s income as dividend income to the extent paid from Pioneer’s current or accumulated “earnings and profits” (as determined under U.S. federal income tax principles). A portion of the cash distributed to Pioneer stockholders by Pioneer after the mergers may exceed Pioneer’s current and accumulated earnings and profits. Cash distributions in excess of Pioneer’s current and accumulated earnings and profits will first be treated as a non- taxable return of capital to the extent of (and reducing, but not below zero) a U.S. holder’s adjusted tax basis in its Pioneer common stock and will thereafter be treated as capital gain from the sale or exchange of such Pioneer common stock. A Pioneer stockholder who is a U.S. holder generally will recognize capital gain or loss on a disposition of its Pioneer common stock.

Pioneer’s ability to utilize its historic U.S. net operating loss carryforwards and those of Parsley may be limited.

As of December 31, 2019, Pioneer and Parsley had U.S. federal net operating loss carryforwards (“NOLs”) of approximately $4.8 billion and $587.1 million, respectively, $2.8 billion and $535.3 million, respectively, of which were incurred prior to January 1, 2018 and will begin to expire, if unused, in 2032 and 2034, respectively, and $2.0 billion and $51.8 million, respectively, of which were incurred on or after January 1, 2018 and will not expire and will be carried forward indefinitely. Pioneer’s ability to utilize these NOLs and other tax attributes to reduce future taxable income following the consummation of the mergers depends on many factors, including its future income, which cannot be assured. Section 382 of the Code (“Section 382”) generally imposes an annual limitation on the amount of NOLs that may be used to offset taxable income when a corporation has undergone an “ownership change” (as determined under Section 382). An ownership change generally occurs if one or more stockholders (or groups of stockholders) who are each deemed to own at least 5% of such corporation’s stock increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. In the event that an ownership change occurs, utilization of the relevant corporation’s NOLs would be subject to an annual limitation under Section 382, generally determined, subject to certain adjustments, by multiplying (i) the fair market value of such corporation’s stock at the time of the ownership change by (ii) a percentage approximately equivalent to the yield on long-term tax-exempt bonds during the month in which the ownership change occurs. Any unused annual limitation may be carried over to later years.

Parsley is expected to undergo an ownership change under Section 382 as a result of the mergers, which, based on information currently available, may trigger a limitation (calculated as described above) on Pioneer’s ability to utilize any historic Parsley NOLs and could cause some of Parsley’s NOLs incurred prior to January 1, 2018 to expire before Pioneer would be able to utilize them to reduce taxable income in future periods. While Pioneer’s issuance of stock in the mergers would, standing alone, be insufficient to result in an ownership change with respect to Pioneer, we cannot assure you that Pioneer will not undergo an ownership change as a result of the mergers taking into account other changes in ownership of Pioneer stock occurring within the relevant three-year period described above. If Pioneer were to undergo an ownership change, it may be prevented from fully utilizing its historic NOLs incurred prior to January 1, 2018.

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Uncertainties associated with the mergers may cause a loss of management personnel and other key employees of Parsley, which could adversely affect the future business and operations of Pioneer following the mergers.

Pioneer and Parsley are dependent on the experience and industry knowledge of their officers and other key employees to execute their business plans. Pioneer’s success after the mergers will depend in part upon its ability to retain key management personnel and other key employees. Current and prospective employees of Parsley may experience uncertainty about their roles within Pioneer following the mergers or other concerns regarding the timing and completion of the mergers or the operations of Pioneer following the mergers, any of which may have an adverse effect on the ability of Parsley to retain or attract key management and other key personnel. In addition, the loss of key Parsley personnel could diminish the anticipated benefits of the mergers. No assurance can be given that Pioneer, following the mergers, will be able to retain or attract key management personnel and other key employees of Parsley to the same extent that Pioneer and Parsley have previously been able to retain or attract their own employees.

The business relationships of Pioneer and Parsley may be subject to disruption due to uncertainty associated with the mergers, which could have a material adverse effect on the results of operations, cash flows and financial position of Pioneer or Parsley pending and following the mergers.

Parties with which Pioneer or Parsley do business may experience uncertainty associated with the mergers, including with respect to current or future business relationships with Pioneer or Parsley following the mergers. Pioneer’s and Parsley’s business relationships may be subject to disruption as customers, distributors, suppliers, vendors, landlords, joint venture partners and other business partners may attempt to delay or defer entering into new business relationships, negotiate changes in existing business relationships or consider entering into business relationships with parties other than Pioneer or Parsley following the mergers. These disruptions could have a material and adverse effect on the results of operations, cash flows and financial position of Pioneer or Parsley, regardless of whether the mergers are completed, as well as a material and adverse effect on Pioneer’s ability to realize the expected cost savings and other benefits of the mergers. The risk, and adverse effect, of any disruption could be exacerbated by a delay in completion of the mergers or termination of the merger agreement.

The merger agreement subjects Pioneer and Parsley to restrictions on their respective business activities prior to the effective time.

The merger agreement subjects Pioneer and Parsley to restrictions on their respective business activities prior to the effective time. The merger agreement obligates each of Pioneer and Parsley to use its commercially reasonable efforts to carry on its business in the ordinary course in all material respects, and the merger agreement obligates Parsley to use its commercially reasonable efforts to preserve substantially intact its business organization, substantially preserve its assets, rights and properties in good repair and condition, keep available in all material respects the services of its current officers, employees and consultants and preserve its goodwill and its relationships with material customers, suppliers, licensors, licensees, distributors and others having material business dealings with it. These restrictions could prevent Pioneer and Parsley from pursuing certain business opportunities that arise prior to the effective time and are outside the ordinary course of business. See “The Merger Agreement—Conduct of Business” for additional details.

Parsley directors and executive officers have interests in the mergers that may be different from, or in addition to, the interests of the Parsley stockholders generally.

In considering the recommendation of the Parsley board that Parsley stockholders vote in favor of the Parsley merger proposal and the Parsley compensation proposal, Parsley stockholders should be aware of and take into account the fact that certain Parsley directors and executive officers have interests in the mergers that may be different from, or in addition to, the interests of Parsley stockholders generally. These interests include, among others, TRA termination payments, severance rights and rights to continuing indemnification and

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directors’ and officers’ liability insurance. See “The Mergers—Interests of Certain Parsley Directors and Executive Officers in the Mergers” for a more detailed description of these interests. The Parsley board was aware of and carefully considered these interests, among other matters, in evaluating the terms and structure, and overseeing the negotiation, of the mergers, in approving the merger agreement and the transactions contemplated thereby, including the mergers, and in recommending that the Parsley stockholders approve the Parsley merger proposal and the Parsley compensation proposal.

The merger agreement limits Pioneer’s and Parsley’s respective ability to pursue alternatives to the mergers, may discourage other companies from making a favorable alternative transaction proposal and, in specified circumstances, could require Pioneer or Parsley to pay the other party a termination fee.

The merger agreement contains certain provisions that restrict each of Pioneer’s and Parsley’s ability to solicit, initiate, endorse, knowingly encourage or knowingly facilitate any inquiry, proposal or offer that constitutes, or would reasonably be expected to lead to, an acquisition proposal with respect to Pioneer or Parsley, as applicable, and Pioneer and Parsley have each agreed to certain terms and conditions relating to their ability to enter into, continue or otherwise participate in any discussions or negotiations regarding, or furnish to a third party any non-public information or data with respect to, or otherwise cooperate in any way with, any acquisition proposal. Further, even if the Pioneer board or the Parsley board withdraws, modifies or qualifies in any manner adverse to the other party its recommendation with respect to the Pioneer stock issuance proposal or the Parsley merger proposal, as applicable, unless the merger agreement has been terminated in accordance with its terms, both parties will still be required to submit the Pioneer stock issuance proposal or the Parsley merger proposal, as applicable, to a vote at their respective special meetings. In addition, Pioneer and Parsley generally have an opportunity to offer to modify the terms of the merger agreement in response to any competing acquisition proposals or intervening events before the Parsley board or Pioneer board, respectively, may withdraw, modify or qualify their respective recommendations. The merger agreement further provides that under specified circumstances, including after receipt of certain alternative acquisition proposals, Parsley may be required to pay Pioneer a cash termination fee equal to $135.0 million or Pioneer may be required to pay Parsley a cash termination fee equal to $270.0 million. See “The Merger Agreement—Termination Fees and Expense Reimbursement” for additional details.

These provisions could discourage a potential third-party acquirer or other strategic transaction partner that might have an interest in acquiring all or a significant portion of Parsley or Pioneer from considering or pursuing an alternative transaction with either party or proposing such a transaction, even if it were prepared, in Parsley’s case, to pay consideration with a higher per share value than the total value proposed to be paid or received in the mergers. These provisions might also result in a potential third-party acquirer or other strategic transaction partner proposing to pay a lower price than it might otherwise have proposed to pay because of the added expense of the termination fee that may become payable in certain circumstances.

The financial forecasts are based on various assumptions that may not be realized.

The financial estimates set forth in the forecasts included under the sections “The Mergers—Certain Pioneer Unaudited Prospective Financial and Operating Information” and “The Mergers—Certain Parsley Unaudited Prospective Financial and Operating Information” were based on assumptions of, and information available to, Pioneer’s management and Parsley’s management, as applicable, when prepared, and these estimates and assumptions are subject to uncertainties, many of which are beyond Pioneer’s and Parsley’s control and may not be realized. Many factors mentioned in this joint proxy statement/prospectus, including the risks outlined in this “Risk Factors” section and the events or circumstances described under “Cautionary Statement Regarding Forward-Looking Statements,” will be important in determining the combined company’s future results. As a result of these contingencies, actual future results may vary materially from Pioneer’s and Parsley’s estimates. In view of these uncertainties, the inclusion of financial estimates in this joint proxy statement/prospectus is not and should not be viewed as a representation that the forecasted results will necessarily reflect actual future results.

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Pioneer’s and Parsley’s financial estimates were not prepared with a view toward public disclosure, and such financial estimates were not prepared with a view toward compliance with published guidelines of any regulatory or professional body. Further, any forward-looking statement speaks only as of the date on which it is made, and neither Pioneer nor Parsley undertakes any obligation, other than as required by applicable law, to update the financial estimates herein to reflect events or circumstances after the date those financial estimates were prepared or to reflect the occurrence of anticipated or unanticipated events or circumstances.

The financial estimates of Pioneer and Parsley included in this joint proxy statement/prospectus have been prepared by, and are the responsibility of, Pioneer and Parsley, as applicable. Moreover, neither Pioneer’s nor Parsley’s independent accountants, nor any other independent accountants, have compiled, examined or performed any procedures with respect to Pioneer’s or Parsley’s prospective financial information contained herein, nor have they expressed any opinion or any other form of assurance on such information or achievability thereof, and, accordingly, such independent accountants assume no responsibility for, and disclaim any association with, Pioneer’s and Parsley’s prospective financial information. The reports of such independent accountants included or incorporated by reference herein, as applicable, relate exclusively to the historical financial information of the entities named in those reports and do not cover any other information in this joint proxy statement/prospectus and should not be read to do so. See “The Mergers—Certain Pioneer Unaudited Prospective Financial and Operating Information” and “The Mergers—Certain Parsley Unaudited Prospective Financial and Operating Information” for more information.

The opinions of Pioneer’s and Parsley’s respective financial advisors will not reflect changes in circumstances between the signing of the merger agreement and the completion of the mergers.

Each of Pioneer and Parsley has received opinions from its financial advisors in connection with the signing of the merger agreement, but has not obtained any updated opinion from its financial advisors as of the date of this joint proxy statement/prospectus. Changes in the operations and prospects of Pioneer or Parsley, general market and economic conditions and other factors that may be beyond the control of Pioneer or Parsley, and on which the companies’ respective financial advisors’ opinions were based, may significantly alter the value of Pioneer or Parsley or the prices of the shares of Pioneer common stock or Parsley Class A common stock by the time the mergers are completed. The opinions do not speak as of the time the mergers will be completed or as of any date other than the date of such opinions. Because neither Pioneer nor Parsley currently anticipates asking its financial advisors to update their opinions, the opinions will not address the fairness of the merger consideration from a financial point of view at the time the mergers are completed. The Pioneer board’s recommendation that Pioneer stockholders vote in favor of the Pioneer stock issuance proposal and the Parsley board’s recommendation that Parsley stockholders vote in favor of the Parsley merger proposal, however, are made as of the date of this joint proxy statement/prospectus.

Failure to complete the mergers could negatively impact Pioneer’s or Parsley’s stock price and have a material adverse effect on their results of operations, cash flows and financial positions.

If the mergers are not completed for any reason, including as a result of failure to obtain all requisite regulatory approvals or if the Pioneer stockholders or Parsley stockholders fail to approve the applicable proposals, the ongoing businesses of Pioneer and Parsley may be materially adversely affected and, without realizing any of the benefits of having completed the mergers, Pioneer and Parsley would be subject to a number of risks, including the following:

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If the mergers are not completed, the risks described above may materialize and they may have a material adverse effect on Pioneer’s or Parsley’s results of operations, cash flows, financial position and stock prices.

The shares of Pioneer common stock to be received by Parsley Class A stockholders and Parsley LLC unitholders upon completion of the mergers will have different rights from shares of Parsley common stock or Parsley LLC units.

Upon completion of the mergers, Parsley Class A stockholders and Parsley LLC unitholders (other than Parsley) will no longer be stockholders of Parsley or unitholders of Parsley LLC. Instead, former Parsley Class A stockholders and Parsley LLC unitholders (other than Parsley) will become Pioneer stockholders, and, while their rights as Pioneer stockholders will continue to be governed by the laws of the state of Delaware, their rights will be subject to and governed by the terms of the Pioneer certificate of incorporation and the Pioneer bylaws. The laws of the state of Delaware and terms of the Pioneer certificate of incorporation and the Pioneer bylaws are in some respects different than the terms of the Parsley certificate of incorporation, the Parsley bylaws and the Parsley LLC agreement, which currently govern the rights of Parsley stockholders and Parsley LLC unitholders, as applicable. See “Comparison of Equityholder Rights” for a discussion of the different rights associated with shares of Pioneer common stock, shares of Parsley common stock and Parsley LLC units.

Completion of the mergers may trigger change in control or other provisions in certain agreements to which Parsley is a party.

The completion of the mergers may trigger change in control or other provisions in certain agreements to which Parsley, Parsley LLC or another subsidiary of Parsley is a party. If Pioneer, Parsley or their respective subsidiaries are unable to negotiate waivers of those provisions, the counterparties may exercise their rights and remedies under the agreements, potentially terminating the agreements, or seeking monetary damages. Even if Pioneer and Parsley are able to negotiate waivers, the counterparties may require a fee for such waivers or seek to renegotiate the agreements on terms less favorable to Parsley.

The indentures governing Parsley’s $650,000,000 principal amount outstanding of 5.375% senior notes due 2025, $448,031,000 principal amount outstanding of 5.250% senior notes due 2025, $494,607,000 principal amount outstanding of 5.875% senior notes due 2026, $700,000,000 principal amount outstanding of 5.625% senior notes due 2027 and $399,472,000 principal amount outstanding of 4.125% senior notes due 2028 (collectively, the “Parsley notes”) require Parsley LLC to make an offer to repurchase the Parsley notes at a purchase price in cash equal to 101% of the aggregate principal amount of notes repurchased, plus accrued and unpaid interest (collectively, the “change of control purchase price”), within 30 days of the occurrence of a

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change of control transaction. A “change of control” transaction, as defined under the Parsley notes indentures, occurs when, among other things, a transaction is consummated and, as a result, any person (other than certain legacy holders) becomes the beneficial owner of more than 50% of Parsley LLC’s voting stock (as defined in the applicable indenture). In the case of the 5.875% senior notes due 2026 and the 4.125% senior notes due 2028, however, such transaction is not a “change of control” transaction unless it is followed by a ratings decline within 90 days or 60 days, respectively.

Under each of the indentures governing the 5.375% senior notes due 2025, the 5.250% senior notes due 2025, and the 5.625% senior notes due 2027, the completion of the mergers is anticipated to constitute a change of control and, as a result, Parsley LLC will be required to make an offer to each holder of such Parsley notes to purchase all or any part of that holder’s notes at the change of control purchase price. If the mergers are followed by a ratings decline (as described in the applicable indenture, within 90 days for the 5.875% senior notes due 2026 or within 60 days for the 4.125% senior notes due 2028), a “change of control” may be deemed to have occurred for those notes as well. If the holders of the Parsley notes accept any such offer of repurchase of their notes, such repurchase could significantly affect the liquidity, business, liabilities and financial condition of Pioneer following the completion of the mergers.

In addition, the completion of the transaction will constitute a change of control under Parsley LLC’s revolving credit facility (the “Parsley revolving credit facility”). As a result, at the direction of the lenders holding a majority of the outstanding loans under the Parsley revolving credit facility, the commitments under the Parsley revolving credit facility may be terminated and the outstanding balance under the Parsley revolving credit facility may be accelerated and become due and payable by Parsley LLC in connection with the completion of the mergers. As of September 30, 2020, Parsley LLC had $305 million of outstanding borrowings under the Parsley revolving credit facility.

Additionally, the completion of the mergers will constitute a change of control under the Parsley employment agreements (as defined below).

Further, the mergers will constitute a change of control event under the tax receivable agreement. In connection with its initial public offering (“IPO”) in 2014, Parsley entered into the tax receivable agreement with the TRA holders, pursuant to which Parsley agreed to make specified future payments to the TRA holders relating to tax attributes generated to Parsley’s benefit in future taxable exchanges of Parsley LLC units by TRA holders, with such payment obligations accelerating upon a change of control (as defined in the tax receivable agreement). It is estimated, as of November 30, 2020, that the TRA termination payments made upon the completion of the mergers to the TRA holders will be, in the aggregate, approximately $164.0 million.

For additional details, see “The Mergers—Interests of Certain Parsley Directors and Executive Officers in the Mergers.”

Pioneer and Parsley are expected to incur significant transaction costs in connection with the mergers, which may be in excess of those anticipated by them.

Pioneer and Parsley have incurred and are expected to continue to incur a number of non-recurring costs associated with negotiating and completing the mergers, combining the operations of the two companies and achieving desired synergies. These costs have been, and will continue to be, substantial and, in many cases, will be borne by Pioneer and Parsley whether or not the mergers are completed. A substantial majority of non- recurring expenses will consist of transaction costs and include, among others, fees paid to financial, legal, accounting and other advisors, employee retention, severance and benefit costs and filing fees. Pioneer will also incur costs related to formulating and implementing integration plans, including facilities and systems consolidation costs and other employment-related costs. Pioneer and Parsley will continue to assess the magnitude of these costs, and additional unanticipated costs may be incurred in connection with the mergers and the integration of the two companies’ businesses. While Pioneer and Parsley have assumed that a certain level of

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expenses would be incurred, there are many factors beyond their control that could affect the total amount or the timing of the expenses. The elimination of duplicative costs, as well as the realization of other efficiencies related to the integration of the businesses, may not offset integration-related costs and achieve a net benefit in the near term, or at all. The costs described above and any unanticipated costs and expenses, many of which will be borne by Pioneer or Parsley even if the mergers are not completed, could have an adverse effect on Pioneer’s or Parsley’s financial condition and operating results.

Litigation related to the mergers could result in an injunction preventing the completion of the mergers and/or substantial costs to Pioneer and Parsley.

Securities class action lawsuits and derivative lawsuits are often brought against public companies that have entered into acquisition, merger, or other business combination agreements. Even if such a lawsuit is without merit, defending against these claims can result in substantial costs and divert management time and resources. An adverse judgment could result in monetary damages, which could have a negative impact on Pioneer’s and Parsley’s respective liquidity and financial condition.

Lawsuits that may be brought against Pioneer, Parsley or their respective directors could also seek, among other things, injunctive relief or other equitable relief, including a request to rescind parts of the merger agreement already implemented and to otherwise enjoin the parties from consummating the mergers. One of the conditions to the closing of the mergers is that no injunction by any court or other tribunal of competent jurisdiction has been entered and continues to be in effect and no law has been adopted or is effective, in either case that prohibits or makes illegal the closing of the mergers. Consequently, if a plaintiff is successful in obtaining an injunction prohibiting completion of the mergers, that injunction may delay or prevent the mergers from being completed within the expected timeframe or at all, which may adversely affect Pioneer’s and Parsley’s respective business, financial position and results of operation. Either Pioneer or Parsley may terminate the merger agreement if any court of competent jurisdiction or other governmental entity issues any judgment, order, injunction, rule or decree, or takes any other action restraining, enjoining or otherwise prohibiting any of the transactions contemplated by the merger agreement, and such judgment, order, injunction, rule, decree or other action becomes final and nonappealable, so long as the party seeking to terminate the merger agreement has used its reasonable best efforts to contest, appeal and remove such judgment, order, injunction, rule, decree, ruling or other action in accordance with the terms of the merger agreement.

There can be no assurance that any of the defendants will be successful in the outcome of any pending lawsuit or any potential future lawsuits. The defense or settlement of any lawsuit or claim that remains unresolved at the time the mergers are completed may adversely affect Pioneer’s or Parsley’s business, financial condition, results of operations and cash flows.

See the section titled “The Mergers—Litigation Related to the Mergers” for more information about litigation related to the mergers that has been commenced prior to the date of this joint proxy statement/prospectus.

The mergers may be completed even though material adverse changes subsequent to the announcement of the mergers, such as industry-wide changes or other events, may occur.

In general, either party can refuse to complete the mergers if there is a material adverse change affecting the other party. However, some types of changes do not permit either party to refuse to complete the transaction, even if such changes would have a material adverse effect on either of the parties. For example, a worsening of Pioneer’s or Parsley’s financial condition or results of operations due to a decrease in commodity prices or general economic conditions would not give the other party the right to refuse to complete the mergers. In addition, the parties have the ability, but are under no obligation, to waive any material adverse change that results in the failure of a closing condition and instead proceed with completing the mergers. If adverse changes occur that affect either party but the parties are still required or voluntarily decide to complete the transaction, Pioneer’s share price, business and financial results after the mergers may suffer.

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Parsley Class A stockholders are not entitled to appraisal rights in connection with the mergers.

Appraisal rights are statutory rights that enable stockholders to dissent from certain extraordinary transactions, such as certain mergers, and to demand that the corporation pay the fair value for their shares as determined by a court in a judicial proceeding instead of receiving the consideration offered to stockholders in connection with the applicable transaction. Under the DGCL, Parsley Class A stockholders will not have rights to an appraisal of the fair value of their shares in connection with the mergers because they are receiving shares of Pioneer common stock and Pioneer common stock is expected to continue to be traded on the NYSE during the pendency of and following the effectiveness of the mergers. However, Parsley Class B stockholders who do not vote in favor of the Parsley merger proposal will be entitled to exercise appraisal rights under the DGCL, solely with respect to their shares of Parsley Class B common stock (and not, for the avoidance of doubt, with respect to any shares of Parsley Class A common stock or Parsley LLC units held by them), in connection with the mergers if they take certain actions and meet certain conditions. See “The Mergers—Appraisal Rights or Dissenters’ Rights” for more information about appraisal rights in connection with the mergers.

The COVID-19 outbreak may adversely affect Pioneer’s and Parsley’s ability to timely consummate the mergers.

COVID-19 and the various precautionary measures attempting to limit its spread taken by many governmental authorities worldwide has had a severe effect on global markets and the global economy. The extent to which the COVID-19 pandemic impacts Pioneer’s and Parsley’s respective business operations will depend on future developments, which are highly uncertain and cannot be predicted, including new information which may emerge concerning the severity of COVID-19 and the nature and extent of governmental actions taken to contain it or treat its impact, among others. COVID-19 and official actions in response to it have made it more challenging for Pioneer, Parsley and relevant third parties to adequately staff their respective businesses and operations, and may cause delay in the companies’ ability to obtain the relevant approvals for the consummation of the mergers.

Risks Relating to Pioneer Following the Mergers

Pioneer may be unable to integrate the business of Parsley successfully or realize the anticipated benefits of the mergers.

The mergers involve the combination of two companies that currently operate as independent public companies. The combination of two independent businesses is complex, costly and time consuming, and each of Pioneer and Parsley will be required to devote significant management attention and resources to integrating their respective business practices and operations. Potential difficulties that the companies may encounter as part of the integration process include the following:

In addition, Pioneer and Parsley have previously operated and, until the completion of the mergers, will continue to operate, independently. It is possible that the integration process could result in:

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Any of these issues could adversely affect each company’s ability to maintain relationships with customers, suppliers, employees and other constituencies or achieve the anticipated benefits of the mergers, or could reduce each company’s earnings or otherwise adversely affect the business and financial results of Pioneer following the mergers.

The synergies attributable to the mergers may vary from expectations.

Pioneer may fail to realize the anticipated benefits and synergies expected from the mergers, which could adversely affect its business, financial condition and operating results. The success of the mergers will depend, in significant part, on Pioneer’s ability to successfully integrate the acquired business and realize the anticipated strategic benefits and synergies from the combination. Pioneer believes that the addition of Parsley will complement Pioneer’s strategy by providing operational and financial scale, increasing free cash flow, and enhancing Pioneer’s corporate rate of return. However, achieving these goals requires, among other things, realization of the targeted cost synergies expected from the mergers. The anticipated benefits of the transaction may not be realized fully or at all, or may take longer to realize than expected. Actual operating, technological, strategic and revenue opportunities, if achieved at all, may be less significant than expected or may take longer to achieve than anticipated. If Pioneer is not able to achieve these objectives and realize the anticipated benefits and synergies expected from the mergers within the anticipated timing or at all, Pioneer’s business, financial condition and operating results may be adversely affected.

The future results of Pioneer following the mergers will suffer if Pioneer does not effectively manage its expanded operations.

Following the mergers, the size and geographic footprint of the business of Pioneer will increase. Pioneer’s future success will depend, in part, upon its ability to manage this expanded business, which may pose substantial challenges for management, including challenges related to the management and monitoring of new operations and basins and associated increased costs and complexity. Pioneer may also face increased scrutiny from governmental authorities as a result of the increase in the size of its business. There can be no assurances that Pioneer will be successful or that it will realize the expected operating efficiencies, cost savings, revenue enhancements or other benefits currently anticipated from the mergers.

The mergers may result in a loss of customers, distributors, suppliers, vendors, landlords, joint venture partners and other business partners and may result in the termination of existing contracts.

Following the mergers, some of the customers, distributors, suppliers, vendors, landlords, joint venture partners and other business partners of Pioneer or Parsley may terminate or scale back their current or prospective business relationships with Pioneer. Some customers may not wish to source a larger percentage of their needs from a single company or may feel that Pioneer is too closely allied with one of their competitors. In addition, Pioneer and Parsley have contracts with customers, distributors, suppliers, vendors, landlords, joint venture partners and other business partners that may require Pioneer or Parsley to obtain consents from these other parties in connection with the mergers, which may not be obtained on favorable terms or at all. If relationships with customers, distributors, suppliers, vendors, landlords, joint venture partners and other business partners are adversely affected by the mergers, or if Pioneer, following the mergers, loses the benefits of the contracts of Pioneer or Parsley, Pioneer’s business and financial performance could suffer.

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The unaudited pro forma combined financial statements and the summary pro forma combined oil, NGL and gas reserve and production data included in this joint proxy statement/prospectus are based on a number of preliminary estimates and assumptions, and the actual results of operations, cash flows and financial position of Pioneer after the mergers may differ materially.

The unaudited pro forma information in this joint proxy statement/prospectus is presented for illustrative purposes only, has been prepared based on available information and certain assumptions and estimates that Pioneer and Parsley believe are reasonable, and is not necessarily indicative of what Pioneer’s actual financial position or results of operations would have been had the pro forma events been completed on the dates indicated. Further, Pioneer’s actual results and financial position after the pro forma events occur may differ materially and adversely from the unaudited pro forma information included in this joint proxy statement/prospectus. The unaudited pro forma combined financial statements have been prepared with the assumption that Pioneer will be identified as the acquirer under GAAP and reflect adjustments based upon preliminary estimates of the fair value of assets to be acquired and liabilities to be assumed.

Following the completion of the mergers, Pioneer may incorporate Parsley’s hedging activities into Pioneer’s business, and Pioneer may be exposed to additional commodity price risks arising from such hedges.

To mitigate its exposure to changes in commodity prices, Parsley hedges oil prices from time to time, primarily through the use of commodity derivative contracts. If Pioneer assumes existing Parsley hedges, Pioneer will bear the economic impact of all of Parsley’s current hedges following the completion of the mergers. Actual crude oil prices may differ from the combined company’s expectations and, as a result, such hedges may or may not have a negative impact on Pioneer’s business.

Other Risks Relating to Pioneer and Parsley

As a result of entering into the merger agreement, Pioneer’s and Parsley’s businesses are and will be subject to the risks described above. In addition, Pioneer and Parsley are, and following completion of the mergers, Pioneer will be, subject to the risks described in Pioneer’s and Parsley’s Annual Report on Form 10-K for the year ended December 31, 2019 as updated by subsequent Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, which are filed with the SEC and incorporated by reference into this joint proxy statement/prospectus. See “Where You Can Find More Information” for the location of information incorporated by reference into this joint proxy statement/prospectus.

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PIONEER SPECIAL MEETING

General

This joint proxy statement/prospectus is being provided to Pioneer stockholders as part of a solicitation of proxies by the Pioneer board for use at the Pioneer special meeting and at any adjournments or postponements of such special meeting. This joint proxy statement/prospectus provides Pioneer stockholders with important information about the Pioneer special meeting and should be read carefully in its entirety.

Date, Time and Place of the Pioneer Special Meeting

The Pioneer special meeting will be a virtual meeting conducted exclusively via live webcast online at www.virtualshareholdermeeting.com/PXD21SM starting at 9:00 a.m. Central Time (with log-in beginning at 8:45 a.m. Central Time) on January 12, 2021. Pioneer stockholders will be able to attend the Pioneer special meeting online and vote shares electronically at the meeting by going to www.virtualshareholdermeeting.com/PXD21SM and entering the 16-digit control number included on the proxy card or voting instruction form you received. Because the Pioneer special meeting is completely virtual and being conducted via live webcast, stockholders will not be able to attend the meeting in person.

Purpose of the Pioneer Special Meeting

The Pioneer special meeting is being held to consider and vote on a proposal to approve the issuance of shares of Pioneer common stock in the mergers and other shares of Pioneer common stock reserved for issuance in connection with the mergers, in each case pursuant to the terms of the merger agreement, which is referred to as the Pioneer stock issuance proposal.

Recommendation of the Pioneer Board

The Pioneer board unanimously recommends that Pioneer stockholders vote “FOR” the Pioneer stock issuance proposal.

This joint proxy statement/prospectus contains important information regarding the Pioneer stock issuance proposal and factors that Pioneer stockholders should consider when deciding how to cast their votes. Pioneer stockholders are encouraged to read the entire document carefully, including the annexes to and documents incorporated by reference into this joint proxy statement/prospectus, for more detailed information regarding the merger agreement, including the Pioneer stock issuance proposal, and the mergers.

Voting by Directors and Executive Officers

On November 30, 2020, Pioneer directors and executive officers, and their affiliates, as a group, beneficially owned and were entitled to vote 1,044,372 shares of Pioneer common stock, or approximately 0.6% of the issued and outstanding shares of Pioneer common stock. Although none of them has entered into any agreement obligating them to do so as a director or executive officer of Pioneer, Pioneer currently expects that all of its directors and executive officers will vote their shares “FOR” the Pioneer stock issuance proposal.

Attendance at the Pioneer Special Meeting

Only Pioneer stockholders of record on the Pioneer record date, beneficial owners of Pioneer common stock on the Pioneer record date and holders of valid proxies for the Pioneer special meeting may attend the virtual Pioneer special meeting. Participating stockholders who log-on to the meeting using his, her or its unique 16-digit control number will also be able to examine the stockholder list during the Pioneer special meeting by following the instructions provided on the meeting website.

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Submitting Questions for the Virtual Pioneer Special Meeting

Pioneer stockholders attending the virtual meeting will be in a listen-only mode and will not be able to speak during the webcast. However, in order to maintain the interactive nature of the virtual meeting, stockholders are able submit questions before the meeting at www.proxyvote.com.

Limitations on Submitting Questions for the Virtual Pioneer Special Meeting

Pioneer will answer questions during the Pioneer special meeting that are relevant to meeting matters, comply with the meeting rules of conduct and have been submitted prior to the start of the Pioneer special meeting, subject to time constraints. However, Pioneer reserves the right to exclude questions that are not pertinent to meeting matters or to edit profanity or other inappropriate language. Each stockholder is limited to a total of one question that must be related to the business of the Pioneer special meeting. Each question should cover only one topic and be as succinct as possible. If Pioneer receives substantially similar questions, Pioneer will group such questions together and provide a single response to avoid repetition. The questions of all Pioneer stockholders are welcome. However, the purpose of the Pioneer special meeting must be observed and questions that are not directly related to the business of Pioneer or are not otherwise in good taste, related to personal grievances or otherwise inappropriate (as determined by the chairman of the meeting) will not be answered.

Record Date

The Pioneer board has fixed the close of business on December 7, 2020 as the Pioneer record date for the determination of the Pioneer stockholders entitled to receive notice of, and to vote at, the Pioneer special meeting. The Pioneer stockholders of record on the Pioneer record date are the only Pioneer stockholders that are entitled to receive notice of, and to vote at, the Pioneer special meeting or any adjournments or postponements of the Pioneer special meeting.

Participants in the Pioneer Natural Resources USA, Inc. 401(k) and Matching Plan

Participants in the Pioneer Natural Resources USA, Inc 401(k) Plan (the “Pioneer 401(k) Plan”) who have shares of Pioneer common stock credited to their plan account as of the record date will have the right to direct the Pioneer 401(k) Plan trustee how to vote those shares. The trustee will vote the shares in a participant’s Pioneer 401(k) Plan account in accordance with the participant’s instructions or, if no instructions are received prior to 4:00 p.m. Central Time on January 7, 2021, the shares credited to that participant’s account will be voted by the trustee in the same proportion as it votes shares for which it did receive timely instructions. Information as to how participants voted the shares credited to their Pioneer 401(k) Plan account will not be disclosed to Pioneer. If a participant holds Pioneer common stock outside of the Pioneer 401(k) Plan, the participant will need to vote those shares separately.

Outstanding Shares and Voting Rights of Pioneer Stockholders

On November 30, 2020, there were 164,418,493 shares of Pioneer common stock issued and outstanding, held by 9,120 holders of record. Each issued and outstanding share of Pioneer common stock entitles its holder of record to one vote at the Pioneer special meeting.

Stockholder List

A complete list of registered Pioneer stockholders entitled to vote at the Pioneer special meeting will be available for inspection at Pioneer’s principal executive offices at 777 Hidden Ridge, Irving, Texas 75038, during ordinary business hours, for a period of no less than ten days before the Pioneer special meeting and will be available during the virtual Pioneer special meeting at www.virtualshareholdermeeting.com/PXD21SM. If a Pioneer stockholder wants to inspect the stockholder list, such stockholder should call the Pioneer corporate secretary at (972) 444-9001 to schedule an appointment or request access.

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Quorum; Abstentions and Broker Non-Votes

In order for business to be conducted at the Pioneer special meeting, a quorum must be present. A quorum at the Pioneer special meeting requires the presence of the holders of a majority of the total issued and outstanding shares of Pioneer common stock entitled to vote, present virtually or represented by proxy, at the Pioneer special meeting. An abstention occurs when a stockholder is present for purposes of a quorum by virtually attending the Pioneer special meeting and either does not vote or submits a ballot marked “abstain”. An abstention also occurs when a stockholder does not attend the meeting virtually and instead submits a proxy with an “abstain” instruction. Abstentions will be counted for purposes of determining whether there is a quorum at the Pioneer special meeting. Because it is expected that the only matter to be voted on at the Pioneer special meeting will be non-routine under NYSE rules, brokers will not have discretionary authority to vote on the Pioneer stock issuance proposal; therefore, if you do not provide voting instructions to your broker, bank or other nominee, your shares will not count towards determining whether a quorum is present and your shares will not be voted on the Pioneer stock issuance proposal.

Adjournment

If a quorum is not present or represented or if there are not sufficient votes for the approval of the Pioneer stock issuance proposal, Pioneer expects that the Pioneer special meeting will be adjourned by the chairman of the Pioneer special meeting to solicit additional proxies. In addition, the holders of a majority in voting power of Pioneer common stock entitled to vote at the Pioneer special meeting who are present online or by proxy at the Pioneer special meeting have the power to adjourn such meeting, whether or not a quorum is present. No notice of the reconvened meeting is required to be given if the date, time and place (including the means of remote communication) are announced at the Pioneer special meeting unless the reconvened meeting is more than 30 days after the date for which notice was originally given. At any reconvened Pioneer special meeting at which a quorum is present, (i) any business may be transacted that may have been transacted at the Pioneer special meeting had a quorum been present and (ii) all proxies will be voted in the same manner as the manner in which such proxies would have been voted at the original convening of the Pioneer special meeting, except for any proxies that have been validly revoked or withdrawn prior to the subsequent meeting.

Vote Required

Approval of the Pioneer stock issuance proposal requires the affirmative vote of holders of a majority of the shares of Pioneer common stock present virtually during the Pioneer special meeting or represented by proxy at the Pioneer special meeting and entitled to vote thereon. Abstentions are considered votes cast and will have the same effect as a vote “against” the Pioneer stock issuance proposal. The failure of any Pioneer stockholder to submit a vote (e.g., by not submitting a proxy and not attending and voting online at the virtual meeting) will not be counted in determining the votes cast in connection with the Pioneer stock issuance proposal and will therefore have no effect on the outcome of the Pioneer stock issuance proposal. Because the Pioneer stock issuance proposal is non-routine under NYSE rules, banks, brokers, and other nominees do not have discretionary authority to vote on the Pioneer stock issuance proposal and will not be able to vote on the Pioneer stock issuance proposal absent instructions from the beneficial owner. The failure of a beneficial owner to provide voting instructions to its bank, broker or other nominee will result in the applicable shares not being counted in determining the votes cast in connection with the Pioneer stock issuance proposal, and will therefore have no effect on the outcome of the Pioneer stock issuance proposal.

How to Vote

Pioneer stockholders of record and beneficial owners of Pioneer common stock on the Pioneer record date may vote their shares of Pioneer common stock by submitting a proxy or may vote virtually online at the Pioneer special meeting by following the instructions provided on the proxy card or voting instruction form received. Pioneer recommends that Pioneer stockholders entitled to vote submit a proxy prior to the Pioneer special meeting even if they plan to attend the virtual Pioneer special meeting.

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Pioneer stockholders are encouraged to submit a proxy promptly. Each valid proxy received in time will be voted at the Pioneer special meeting according to the choice specified, if any. Executed but uninstructed proxies (i.e., proxies that are properly signed, dated and returned but are not marked to tell the proxies how to vote) will be voted in accordance with the recommendations of the Pioneer board.

Record Holders

Pioneer stockholders of record may vote in one of the following ways:

Beneficial Owners

Pioneer stockholders who hold their shares of Pioneer common stock beneficially in “street name” and wish to submit a proxy must provide instructions to the bank, broker or other nominee that holds their shares of record as to how to vote their shares with respect to the Pioneer stock issuance proposal. Most beneficial owners will have a choice of voting before the Pioneer special meeting by proxy over the internet, by telephone or by using a voting instruction form. Each beneficial owner of Pioneer common stock should refer to the voting instruction form received to see what options are available and how to use them. Pioneer stockholders who hold their shares of Pioneer common stock beneficially and wish to vote virtually at the Pioneer special meeting may do so by attending the special meeting, entering his, her or its unique 16-digit control number and voting their shares electronically; however attendance at the virtual Pioneer special meeting will not, in and of itself, constitute a vote or a revocation of a prior proxy.

Proxies and Revocation

Pioneer stockholders of record may revoke their proxies at any time before their shares of Pioneer common stock are voted at the Pioneer special meeting in any of the following ways:

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If a Pioneer stockholder holds shares through a bank, broker or other nominee, such stockholder may change or revoke his, her or its voting instructions before the Pioneer special meeting by providing instructions again through the means specified on his, her or its voting instruction form (with most having the option to do so by internet, telephone or mail), which must be received before 10:59 p.m. Central Time on January 11, 2021. Alternatively, a Pioneer stockholder may also revoke their proxy by attending the Pioneer special meeting virtually, using his, her or its unique 16-digit control number and voting his, her or its shares online during the meeting.

Solicitation of Proxies

Pioneer will pay for the proxy solicitation costs related to the Pioneer special meeting. In addition to sending and making available these materials, some of Pioneer’s directors, officers and other employees may solicit proxies by contacting Pioneer stockholders by telephone, by mail, by e-mail or online. Pioneer stockholders may also be solicited by, among others, news releases issued by Pioneer and/or Parsley, postings on Pioneer’s or Parsley’s websites and social media accounts and advertisements in periodicals. None of Pioneer’s directors, officers or employees will receive any extra compensation for their solicitation services. Pioneer has also retained D.F. King & Co., Inc. as its proxy solicitor to assist in the solicitation of proxies. For these proxy solicitation services, D.F. King & Co., Inc. will receive an estimated fee of approximately $20,000, plus reasonable out-of-pocket expenses and fees for any additional services. Pioneer will also reimburse banks, brokers, and other nominees for their expenses in sending proxy solicitation materials to the beneficial owners of shares of Pioneer common stock and obtaining their proxies.

Other Matters

At this time, Pioneer knows of no other matters to be submitted at the Pioneer special meeting.

Questions and Additional Information

Pioneer stockholders may contact Pioneer’s proxy solicitor with any questions about the Pioneer stock issuance proposal or how to vote or to request additional copies of any materials at:

D.F. King & Co., Inc.

48 Wall Street, 22^nd Floor

New York, NY 10005

Banks and Brokers Call Collect: (212) 269-5550

All Others Call Toll-Free: (800) 859-8509

Email: [email protected]

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THE PIONEER STOCK ISSUANCE PROPOSAL

This joint proxy statement/prospectus is being furnished to you as a stockholder of Pioneer as part of the solicitation of proxies by the Pioneer board for use at the Pioneer special meeting to consider and vote upon a proposal to approve the issuance of shares of Pioneer common stock in the mergers and other shares of Pioneer common stock reserved for issuance in connection with the mergers, in each case pursuant to the terms of the merger agreement, which is attached as Annex A to this joint proxy statement/prospectus. Under the rules of the NYSE, a company listed on the NYSE is required to obtain stockholder approval prior to the issuance of common stock in any transaction or series of related transactions if the number of shares of common stock to be issued is equal to or in excess of 20% of the number of shares of common stock outstanding before the issuance of the common stock. If the mergers are completed, it is currently estimated that Pioneer will issue approximately 52 million shares of Pioneer common stock in connection with the mergers, which will exceed 20% of the shares of Pioneer common stock outstanding before such issuance and for this reason Pioneer must obtain the approval of Pioneer stockholders for that issuance.

In the event the Pioneer stock issuance proposal is approved by the Pioneer stockholders, but the merger agreement is terminated (without the mergers being completed) prior to the issuance of shares of Pioneer common stock pursuant to the merger agreement, Pioneer will not issue any shares of Pioneer common stock as a result of the approval of the Pioneer stock issuance proposal.

The Pioneer board has unanimously determined that the mergers and the other transactions contemplated by the merger agreement are in the best interests of, and are advisable to, Pioneer and the Pioneer stockholders, approved, adopted and declared advisable the merger agreement and the transactions contemplated thereby, and directed that the stock issuance be submitted to Pioneer stockholders for approval.

IF YOU ARE A PIONEER STOCKHOLDER, THE PIONEER BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE “FOR” THE PIONEER STOCK ISSUANCE PROPOSAL.

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PARSLEY SPECIAL MEETING

General

This joint proxy statement/prospectus is being provided to Parsley stockholders as part of a solicitation of proxies by the Parsley board for use at the Parsley special meeting and at any adjournments or postponements of such special meeting. This joint proxy statement/prospectus provides Parsley stockholders with important information about the Parsley special meeting and should be read carefully in its entirety.

Date, Time and Place of the Parsley Special Meeting

The Parsley special meeting will be a virtual meeting conducted exclusively via live webcast online at www.virtualshareholdermeeting.com/PE21SM starting at 9:00 a.m. Central Time (with log-in beginning at 8:45 a.m. Central Time) on January 12, 2021. Parsley stockholders will be able to attend the Parsley special meeting online and vote shares electronically at the meeting by going to www.virtualshareholdermeeting.com/PE21SM and entering the 16-digit control number included on the proxy card or voting instruction form you received. Because the Parsley special meeting is completely virtual and being conducted via live webcast, stockholders will not be able to attend the meeting in person.

Purposes of the Parsley Special Meeting

The Parsley special meeting is being held to consider and vote on the following proposals:

Recommendation of the Parsley Board

The Parsley board unanimously recommends that Parsley stockholders vote:

This joint proxy statement/prospectus contains important information regarding these proposals and factors that Parsley stockholders should consider when deciding how to cast their votes. Parsley stockholders are encouraged to read the entire document carefully, including the annexes to and documents incorporated by reference into this joint proxy statement/prospectus, for more detailed information regarding the merger agreement and the mergers.

The Parsley Compensation Proposal

In considering the recommendations of the Parsley board, Parsley stockholders should be aware that some of Parsley’s directors and executive officers have interests that are different from, or in addition to, the interests

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of Parsley stockholders more generally. For additional information, please see “The Mergers—Interests of Certain Parsley Directors and Executive Officers in the Mergers.”

Section 14A of the Exchange Act, which was enacted as part of the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010, requires that Parsley provide its stockholders with the opportunity to vote to approve, on a non-binding advisory basis, the compensation that may be paid or become payable to Parsley’s NEOs that is based on or otherwise relates to the mergers, as disclosed in this joint proxy statement/prospectus, including the compensation table and the related narrative NEO compensation disclosures set forth in “The Mergers—Interests of Certain Parsley Directors and Executive Officers in the Mergers.” This vote is commonly referred to as a “say on golden parachute” vote. Accordingly, Parsley stockholders are being provided with the opportunity to cast an advisory (i.e., non-binding) vote on those change of control payments.

Parsley stockholders should note that the Parsley compensation proposal is merely an advisory vote that will not be binding on Parsley, Pioneer or their respective boards of directors. Further, the underlying plans and arrangements are contractual in nature and not, by their terms, subject to stockholder approval. Accordingly, regardless of the outcome of the advisory vote, if the mergers are consummated, the eligibility of Parsley’s NEOs for such payments and benefits will not be affected by the advisory vote.

The vote on the Parsley compensation proposal is a vote separate and apart from the vote on the Parsley merger proposal. Accordingly, a Parsley stockholder may vote to approve one proposal and not the other. Because the vote on the Parsley compensation proposal is advisory in nature only, it will not be binding on Parsley or Pioneer, and the approval of the Parsley compensation proposal is not a condition to the completion of the mergers.

Voting by Directors and Executive Officers

As of November 30, 2020, Parsley directors and executive officers, and their affiliates, as a group, beneficially owned 100,960,573 shares of Parsley common stock, or approximately 24.5% of the issued and outstanding shares of Parsley common stock. Although none of them has entered into any agreement obligating them to do so as a director or executive officer of Parsley (other than Mr. Bryan Sheffield, Parsley’s Executive Chairman and Chairman of the Parsley board, pursuant to the Sheffield voting agreement and Mr. S. Wil VanLoh, Jr., who may be deemed to share voting and dispositive power over the Quantum voting agreement shares, pursuant to the Quantum voting agreement), Parsley currently expects that all of its directors and executive officers will vote their shares “FOR” the Parsley merger proposal and “FOR” the Parsley compensation proposal.

Voting and Support Agreement with Quantum

In connection with the execution of the merger agreement, Quantum entered into the Quantum voting agreement with respect to the Quantum voting agreement shares. As of November 30, 2020, Quantum held approximately 15.8% of the combined voting power of the issued and outstanding shares of Parsley common stock.

Pursuant to the Quantum voting agreement, Quantum has agreed to vote all of the Quantum voting agreement shares (i) in favor of the adoption of the merger agreement and the approval of any other matters necessary for consummation of the transactions contemplated by the merger agreement, including the mergers, subject to certain exceptions, and (ii) against specified actions that could reasonably be expected to impede, interfere with, delay, discourage, postpone or adversely affect the mergers or any other transaction contemplated by the merger agreement, including specified actions that contemplate alternative transactions. Under the Quantum voting agreement, Quantum has granted to Pioneer an irrevocable proxy to vote the Quantum voting agreement shares as provided above. Subject to certain exceptions, the Quantum voting agreement restricts Quantum from transferring Parsley common stock until the earlier of the termination of the Quantum voting agreement and the effective time.

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The Quantum voting agreement, including the irrevocable proxy granted thereunder, will terminate upon the date the merger agreement is validly terminated in accordance with its terms. The Quantum voting agreement is attached to this joint proxy statement/prospectus as Annex G.

Voting and Support Agreement with Bryan Sheffield

In connection with the execution of the merger agreement, Mr. Sheffield entered into the Sheffield voting agreement with respect to the Sheffield voting agreement shares. As of November 30, 2020, Mr. Sheffield beneficially owned approximately 7.6% of the combined voting power of the issued and outstanding shares of Parsley common stock.

Pursuant to the Sheffield voting agreement, Mr. Sheffield has agreed to vote all of the Sheffield voting agreement shares (i) in favor of the adoption of the merger agreement and the approval of any other matters necessary for consummation of the transactions contemplated by the merger agreement, including the mergers, subject to certain exceptions, and (ii) against specified actions that could reasonably be expected to impede, interfere with, delay, discourage, postpone or adversely affect the mergers or any other transaction contemplated by the merger agreement, including specified actions that contemplate alternative transactions. Under the Sheffield voting agreement, Mr. Sheffield has granted to Pioneer an irrevocable proxy to vote the Sheffield voting agreement shares as provided above. Subject to certain exceptions, the Sheffield voting agreement restricts Mr. Sheffield from transferring Parsley common stock or Parsley LLC units until the earlier of the termination of the Sheffield voting agreement and the effective time.

In addition, the Sheffield voting agreement contains a lock-up agreement providing that Mr. Sheffield may not, without Pioneer’s prior written consent, subject to limited exceptions, offer, sell, transfer or otherwise dispose of more than 15% of the shares of Pioneer common stock issued to Mr. Sheffield pursuant to the terms of the merger agreement for a period of 90 days following the closing date, or more than 30% of such shares for a period of 180 days following the closing date.

The Sheffield voting agreement, including the irrevocable proxy granted thereunder, will terminate upon the date the merger agreement is validly terminated in accordance with its terms. The Sheffield voting agreement is attached to this joint proxy statement/prospectus as Annex H.

Attendance at the Parsley Special Meeting

Only Parsley stockholders of record on the Parsley record date, beneficial owners of Parsley common stock on the Parsley record date and holders of valid proxies for the Parsley special meeting may attend the virtual Parsley special meeting. Participating stockholders who log-on to the meeting using his, her or its unique 16-digit control number will also be able to examine the stockholder list during the Parsley special meeting by following the instructions provided on the meeting website.

Submitting Questions for the Virtual Parsley Special Meeting

Parsley stockholders attending the virtual meeting will be in a listen-only mode and will not be able to speak during the webcast. However, in order to maintain the interactive nature of the virtual meeting, stockholders are able submit questions before the meeting at www.proxyvote.com.

Limitations on Submitting Questions for the Virtual Parsley Special Meeting

Parsley will answer questions during the Parsley special meeting that are relevant to meeting matters, comply with the meeting rules of conduct and have been submitted prior to the start of the Parsley special meeting, subject to time constraints. However, Parsley reserves the right to exclude questions that are not pertinent to meeting matters or to edit profanity or other inappropriate language. Each stockholder is limited to a

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total of one question that must be related to the business of the Parsley special meeting. Each question should cover only one topic and be as succinct as possible. If Parsley receives substantially similar questions, Parsley will group such questions together and provide a single response to avoid repetition. The questions of all Parsley stockholders are welcome. However, the purpose of the Parsley special meeting must be observed and questions that are not directly related to the business of Parsley or are not otherwise in good taste, related to personal grievances or otherwise inappropriate (as determined by the chairman of the meeting) will not be answered.

Record Date

The Parsley board has fixed the close of business on December 7, 2020 as the Parsley record date for the determination of the Parsley stockholders entitled to receive notice of, and to vote at, the Parsley special meeting. The Parsley stockholders of record on the Parsley record date are the only Parsley stockholders that are entitled to receive notice of, and to vote at, the Parsley special meeting or any adjournments or postponements of the Parsley special meeting.

Outstanding Shares as of Record Date and Voting Rights of Parsley Stockholders

As of November 30, 2020, there were 386,803,883 shares of Parsley Class A common stock and 26,062,891 shares of Parsley Class B common stock issued and outstanding, held by 58 and 23 holders of record, respectively. Each issued and outstanding share of Parsley common stock as of the record date entitles its holder of record to one vote on each matter to be considered at the Parsley special meeting. Parsley stockholders are entitled to vote on each proposal presented.

Stockholder List

A complete list of registered Parsley stockholders entitled to vote at the Parsley special meeting will be available for inspection at Parsley’s principal executive offices at 303 Colorado Street, Austin, Texas 78701, during ordinary business hours, for a period of no less than ten days before the Parsley special meeting and will be available during the virtual Parsley special meeting at www.virtualshareholdermeeting.com/PE21SM. If a Parsley stockholder wants to inspect the stockholder list, such stockholder should call Parsley’s Legal department at (512) 220-7102 to schedule an appointment or request access.