As filed with the Securities and Exchange Commission on April 20, 2010November 21, 2023

Registration No. 333-164620333-[            ]

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM AMENDMENT NO. 2S-4

TO

FORM S-4

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Exxon Mobil CorporationEXXON MOBIL CORPORATION

(Exact Name of Registrant as Specified in Its Charter)

5959 Las Colinas Boulevard22777 Springwoods Village Parkway

Irving,Spring, Texas 75039-229877389-1425

(972) 444-1000940-6000

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

Patrick T. MulvaCraig S. Morford

Vice President, General Counsel and Secretary

Exxon Mobil Corporation

5959 Las Colinas BoulevardSpring, Texas 77389-1425

Irving, Texas 75039-2298

(972) 444-1000940-6000

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent For Service)

Copies to:

Approximate date of commencement of proposed sale of the securities to the public: As soon as practicableFrom time to time after thethis Registration Statement becomes effective date of this registration statement and the effective timeupon completion of the merger of ExxonMobil Investment Corporation (“Merger Sub”),SPQR, LLC, a wholly owned subsidiary of Exxon Mobil Corporation, (“ExxonMobil”), with and into XTO Energy Inc. (“XTO Energy”), as described in the Agreement and Plan of Merger dated as of December 13, 2009 among XTO Energy, ExxonMobil and Merger Sub.Pioneer Natural Resources Company.

If the securities being registered on this form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.  ¨☐

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the “Securities Act”“Securities Act”), check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨☐

If this form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ¨☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, or emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer”filer,” “smaller reporting company,” and “smaller reporting“emerging growth company” in Rule 12b-2 of the Securities Exchange Act of 1934 (the “Exchange Act”).1934.

If applicable, place an X in the box to designate the appropriate rule provision relied upon in conducting this transaction:

Securities Exchange Act Rule 13e-4(i) (Cross-Border Issuer Tender Offer)  ¨☐

Securities Exchange Act Rule 14d-1(d)14d-l(d) (Cross-Border Third-Party Tender Offer)  ¨☐

CALCULATION OF REGISTRATION FEE

Information contained herein is subject to completion or amendment. A registration statement relating to these securities has been filed with the Securities and Exchange Commission. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. ThisThe attached proxy statement/prospectus shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful.

PRELIMINARY — PRELIMINARY—SUBJECT TO COMPLETION — COMPLETION—DATED APRIL 20, 2010NOVEMBER 21, 2023

MERGER PROPOSAL —

TRANSACTION PROPOSED—YOUR VOTE IS VERY IMPORTANT

[—], 2010

Dear XTO Energy Inc. Stockholder:Stockholders of Pioneer Natural Resources Company:

On December 13, 2009, XTO Energy Inc. andOctober 10, 2023, Pioneer Natural Resources Company (“Pioneer”), Exxon Mobil Corporation entered into a merger agreement that provides for XTO Energy to become(“ExxonMobil”) and SPQR, LLC, a wholly owned subsidiary of ExxonMobil. The XTO Energy boardExxonMobil (“Merger Sub”), entered into an Agreement and Plan of directors has determined thatMerger (the “Merger Agreement”), under which, upon the mergerterms and subject to the merger agreement are advisableconditions set forth therein, Merger Sub will merge with and in the best interestsinto Pioneer, with Pioneer surviving as a wholly owned subsidiary of XTO Energy and its stockholders and has approved the merger agreement and the merger.ExxonMobil (the “Merger”).

If the mergerMerger is completed, Pioneer stockholders will receive, in exchange for each outstanding share of XTO EnergyPioneer common stock, will be converted intopar value $0.01 per share, held immediately prior to the right to receive 0.7098 shares of ExxonMobil common stock. Immediately following completion of the merger, it is expected that XTO Energy stockholders will own approximately 8% of the outstandingMerger, 2.3234 shares of ExxonMobil common stock, basedwithout par value (such consideration, the “Merger Consideration”).

Pioneer’s board of directors (the “Pioneer board”) has unanimously approved the Merger Agreement and recommends that Pioneer stockholders vote in favor of adopting the Merger Agreement.

Based on ExxonMobil’s closing stock price on [                ], 2023, the numbermost recent practicable date for which such information was available, the Merger Consideration represented approximately $[                ] in implied value per share of sharesPioneer common stock, which represents a premium of XTO Energyapproximately [    ]% over the closing price of the Pioneer common stock on October 5, 2023, the last trading day prior to media reports that Pioneer and ExxonMobil were in merger discussions. The value of the Merger Consideration to be received in exchange for each share of Pioneer common stock will fluctuate with the market value of ExxonMobil common stock outstanding, on a fully diluted basis, as of April 14, 2010.until the Merger is complete. The Pioneer common stock of each of ExxonMobil and XTO Energy is tradedlisted on theThe New York Stock Exchange (the “NYSE”) under the symbolssymbol “PXD”. The ExxonMobil common stock is listed on the NYSE under the symbol “XOM” and “XTO”, respectively..

We are holding a special meeting of stockholders on [—], 2010 at [—], local time, at [—], to obtain your vote to adopt the merger agreement. Your vote is very important. The mergerMerger cannot be completed unlesswithout adoption of the Merger Agreement by the affirmative vote of holders of a majority of the outstanding shares of XTO EnergyPioneer common stock entitled to vote thereon. Because of this, Pioneer is holding a special meeting of its stockholders on [                ] (the “Special Meeting”) to vote on the proposal necessary to complete the Merger. Information about the Special Meeting, the Merger, the Merger Agreement and the other business to be considered by stockholders at the Special Meeting is contained in this proxy statement/prospectus. The Pioneer board has fixed the close of business on [                ], 2023 as the record date for the adoptiondetermination of Pioneer stockholders entitled to notice of, and to vote at, the Special Meeting. We urge you to read this proxy statement/prospectus and the annexes and documents incorporated by reference carefully. You should also carefully consider the risks that are described in the “Risk Factors” section beginning on page29.

The Pioneer board has unanimously determined that the Merger Agreement and the transactions contemplated thereby, including the Merger, are fair to and in the best interests of Pioneer and its stockholders, approved, adopted and declared advisable the Merger Agreement and the transactions contemplated thereby, including the Merger, in accordance with the requirements of the merger agreementDelaware General Corporation Law (the “DGCL”) and directed that the Merger Agreement be submitted to the Pioneer stockholders for adoption at the special meeting.

a meeting of such stockholders. The XTO EnergyPioneer board of directorsunanimously recommends that XTO EnergyPioneer stockholders vote “FOR” the adoptionproposal to adopt the Merger Agreement and “FOR” the proposal to approve, on a non-binding advisory basis, the compensation that may be paid or become payable to Pioneer’s named executive officers that is based on or otherwise related to the Merger.

Your vote is very important regardless of the merger agreement.number of shares of Pioneer common stock that you own.

On behalf of the XTO Energy board of directors, I invite you to attend the special meeting. Whether or not you expectplan to attend the XTO Energy special meeting in person, we urge you toSpecial Meeting virtually, please submit your proxy as promptlysoon as possible through one ofby following the delivery methods described ininstructions on the accompanying proxy statement/prospectus.card to make sure that your shares are represented at the meeting. If your shares are held in the name of a broker, bank or other nominee, please follow the instructions on the voting instruction form furnished by the broker, bank or other nominee. You must provide voting instructions by filling out the voting instruction form in order for your shares to be voted.

In addition, we urge youThe Special Meeting will be held in a virtual meeting format only. You will not be able to read carefullyattend the accompanying proxy statement/prospectus (and the documents incorporated by reference into the accompanying proxy statement/prospectus) which includes important information about the merger agreement, the proposed merger, XTO Energy, ExxonMobil and the special meeting.Please pay particular attention to the section titled “Risk Factors” beginning on page [—] of the accompanying proxy statement/prospectus.Special Meeting physically in person.

On behalf of the XTO Energy board of directors, thankThank you for your continued support.

Sincerely,Very truly yours,

Scott D. Sheffield

Bob R. SimpsonChief Executive Officer

Chairman of the Board and FounderPioneer Natural Resources Company

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of the Merger or the other transactions described in this proxy statement/prospectus or the securities to be issued underin connection with the accompanying proxy statement/prospectusMerger or determined that the accompanyingif this proxy statement/prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The accompanyingThis proxy statement/prospectus is dated [—], 2010                ], 2023, and is first being mailed to the stockholders of XTO EnergyPioneer on or about [—], 2010.                ], 2023.

ADDITIONAL INFORMATION

The accompanying document is the proxy statement of XTO Energy Inc.Pioneer for its special meeting of stockholdersthe Special Meeting and the prospectus of Exxon Mobil CorporationExxonMobil for the shares of Exxon Mobil CorporationExxonMobil common stock to be issued to Pioneer stockholders as consideration forin the merger.Merger. The accompanying proxy statement/prospectus incorporates by reference important business and financial information about Exxon Mobil CorporationPioneer and XTO Energy Inc.ExxonMobil from documents that are not included in or delivered with the accompanying proxy statement/prospectus. This information is available to you without charge upon your request. You can obtain the documents incorporated by reference into the accompanying proxy statement/prospectus (other than certain exhibits or schedules to these documents), without charge, by requesting them in writing or by telephone from Exxon Mobil CorporationPioneer or XTO Energy Inc.ExxonMobil at the following addresses and telephone numbers:numbers, or through the Securities and Exchange Commission website at www.sec.gov:

In addition, if you have any questions aboutconcerning the mergerMerger Agreement or the Merger or the other transactions contemplated by the Merger Agreement, or the accompanying proxy statement/prospectus, or if you would like additional copies of the accompanyingthis proxy statement/prospectus or documents incorporated by reference herein, or if you need to obtain proxy cards or other information related to the proxy solicitation,help voting your shares of Pioneer common stock, please contact Innisfree M&A Incorporated, thePioneer’s proxy solicitor for XTO Energysolicitor:

MacKenzie Partners, Inc., toll-free at (877) 750-5836 (banks and brokers call collect at (212) 750-5833). You will not be charged for any of these documents that you request.

1407 Broadway, 27th Floor

New York, New York 10018

Call toll free: (800) 322-2995

Email: proxy@mackenziepartners.com

If you would like to request documents, please do so by [—], 2010 in order to receive themno later than five business days before the special meeting.date of the Special Meeting (which date is [                ]).

See “Where You Can Find More Information” beginning on page [—]143 of the accompanying proxy statement/prospectus for further information.

810 Houston Street

Fort Worth, Texas 76102

NOTICE OF SPECIAL MEETING OF STOCKHOLDERS

TO BE HELD [                ]

To theour Stockholders:

You are hereby notified that a Special Meeting of Stockholders of XTO Energy Inc.:

Notice is hereby given that a special meeting of stockholders of XTO Energy Inc., which is referred to as XTO Energy,Pioneer Natural Resources Company, a Delaware corporation (“Pioneer”), will be held virtually at www.virtualshareholdermeeting.com/[            ] at [                ] Central Time on [—], 2010 at [—], local time, at [—], solely for the following purposes:

These items of business, including the merger agreement and the proposed merger, are described in detail in the accompanying proxy statement/prospectus.The XTO Energy board of directors has determined that the merger agreement and the transactions contemplated by the merger agreement, including the merger, are advisable and in the best interests of XTO Energy and its stockholders and recommends that XTO Energy stockholders vote “FOR” the proposal to adopt the merger agreement and “FOR” the adjournment of the XTO Energy special meeting if necessary to solicit additional proxies in favor of such adoption.Special Meeting.

Only stockholders of record as of [                ], 2023 are entitled to notice of, and to vote at, the Special Meeting. The Special Meeting will be a virtual only meeting conducted exclusively via live webcast at www.virtualshareholdermeeting.com/[            ] starting at [                ] Central Time (with log-in beginning at [                ] Central Time) on [                ]. You will be able to attend the Special Meeting and vote your shares electronically during the meeting by going to www.virtualshareholdermeeting.com/[            ] and entering the 16-digit control number included on the proxy card or voting instruction form that you received. Because the Special Meeting is completely virtual and being conducted via live webcast, stockholders will not be able to attend the meeting in person. 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 Special Meeting by following the instructions provided on the meeting website.

Stockholders attending the Special Meeting will be in a listen-only mode and will not be able to speak during the webcast. However, stockholders will be able to submit any questions by the close of business on [—], 2010 are entitled to notice in advance of the XTO Energy special meetingSpecial Meeting by visiting [                ]. If you encounter any difficulties during the check-in process or during the Special Meeting, please call [            ], and to vote at the XTO Energy special meeting or at any adjournment or postponement thereof. A list of stockholders entitled to vote at the special meetinga technician will be available in our offices locatedready to assist you starting at 810 Houston Street, Fort Worth, Texas 76102, during regular business hours for a period of no less than ten days[                ] Central Time and until the Special Meeting has finished. Please give yourself sufficient time to log-in and ensure you can hear the streaming audio before the special meeting and at the placestarts.

Completion of the special meeting during the meeting.

AdoptionMerger is conditioned on adoption of the merger agreementMerger Agreement by the XTO EnergyPioneer stockholders, is a condition to the merger andwhich requires the affirmative vote of holders of a majority of the outstanding shares of XTO EnergyPioneer common stock outstanding and entitled to vote thereon. Therefore, yourCompletion of the Merger is not conditioned on approval of the Advisory Compensation Proposal.

The Pioneer board has unanimously determined that the Merger Agreement and the transactions contemplated thereby, including the Merger, are fair to and in the best interests of Pioneer and its

stockholders, approved, adopted and declared advisable the Merger Agreement and the transactions contemplated thereby, including the Merger, in accordance with the requirements of the Delaware General Corporation Law (the “DGCL”) and directed that the Merger Agreement be submitted to the Pioneer stockholders for adoption at a meeting of such stockholders. The Pioneer board unanimously recommends that Pioneer stockholders vote “FOR” the Merger Agreement Proposal and “FOR” the Advisory Compensation Proposal.

Your vote is very important.Your failure to vote your shares will have the same effect as a vote “AGAINST” the adoptionimportant regardless of the merger agreement.

By ordernumber of shares of Pioneer common stock that you own. If you plan to attend the board of directors,

VIRGINIA N. ANDERSON

Secretary

Fort Worth, Texas

[—], 2010

YOUR VOTE IS IMPORTANT!

WHETHER OR NOT YOU EXPECT TO ATTEND THE XTO ENERGY SPECIAL MEETING IN PERSON, WE URGE YOU TO SUBMIT YOUR PROXY AS PROMPTLY AS POSSIBLE (1) THROUGH THE INTERNET, (2) BY TELEPHONE OR (3) BY MARKING, SIGNING AND DATING THE ENCLOSED PROXY CARD AND RETURNING IT IN THE POSTAGE-PAID ENVELOPE PROVIDED.You may revoke yourSpecial Meeting virtually, please follow the instructions as outlined in this proxy statement/prospectus. Whether or changenot you expect to attend the Special Meeting virtually, we urge you to submit your vote at any time beforein advance of the XTO Energy special meeting. If your shares are held in the name of a broker, bank broker or other fiduciary,nominee, please followvote by following the instructions on the voting instruction form furnished by the broker, bank or other nominee. If you hold your shares in your own name, submit a proxy to vote your shares as promptly as possible by (i) visiting the internet site listed on the accompanying proxy card, furnished(ii) calling the toll-free number listed on the proxy card or (iii) submitting your proxy card by mail by using the self-addressed, stamped envelope provided. Submitting a proxy will not prevent you from voting virtually at the meeting, but it will help to you by such record holder.secure a quorum and avoid added solicitation costs. Any eligible holder of Pioneer common stock may vote virtually at the Special Meeting, thereby revoking any previous proxy. In addition, a proxy may also be revoked in writing before the Special Meeting in the manner described in the proxy statement/prospectus of which this notice is a part.

The proxy statement/prospectus of which this notice is a part provides a detailed description of the Merger and the Merger Agreement and the other matters to be considered at the Special Meeting. We urge you to carefully read the accompanyingthis proxy statement/prospectus, including allany documents incorporated by reference intoherein, and the accompanying proxy statement/prospectus, and its annexes carefully and in their entirety. In particular, we urge you to carefully read the section entitled “Risk Factors” beginning on page 29.

If you have any questions concerning the merger, the special meetingMerger or the accompanyingthis proxy statement/prospectus, would like additional copies of the accompanying proxy statement/prospectus or need help voting your shares of XTO EnergyPioneer common stock, please contact XTO Energy’sPioneer’s proxy solicitor:

Innisfree M&A IncorporatedMacKenzie Partners, Inc.

501 Madison Avenue, 20th1407 Broadway, 27th Floor

New York, New York 1002210018

Stockholders, call toll-free: (877) 750-5836Call toll free: (800) 322-2995

Banks and brokers, call collect: (212) 750-5833

TABLE OF CONTENTS

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QUESTIONS AND ANSWERS ABOUT THE MERGER AND THE SPECIAL MEETING

The following are some questions that you, as a stockholder of XTO Energy,Pioneer, may have regarding the mergerMerger and other matters being considered at the special meeting of Pioneer stockholders (the “Special Meeting”) and brief answers to those questions. You are urgedTo better understand these matters, and for a description of the legal terms governing the Merger, Pioneer urges you to carefully read carefullythe remainder of this proxy statement/prospectus andbecause the other documents referred toinformation in this proxy statement/prospectus in their entirety because this section maydoes not provide all of the information that ismight be important to you with respect to the mergerMerger and the special meeting.other matters being considered at the Special Meeting. Additional important information is also contained in the annexes to this proxy statement/prospectus and the documents incorporated by reference into,in this proxy statement/prospectus. See “Where You Can Find More Information” beginning on page 143 of this proxy statement/prospectus.

Q: Why am I receiving this document?

A: Exxon Mobil Corporation, a New Jersey corporation (“ExxonMobil”), SPQR, LLC, a Delaware limited liability company and a wholly owned subsidiary of ExxonMobil (“Merger Sub”), and Pioneer Natural Resources Company, a Delaware corporation (“Pioneer”), have entered into an Agreement and Plan of Merger, dated as of October 10, 2023 (as it may be amended from time to time, the “Merger Agreement”), providing for the merger of Merger Sub with and into Pioneer (the “Merger”), with Pioneer surviving the Merger as a wholly owned subsidiary of ExxonMobil. In order to complete the Merger, Pioneer stockholders must approve the proposal to adopt the Merger Agreement and all other conditions to the Merger must be satisfied or waived.

Pioneer will hold the Special Meeting to obtain approval of the Merger Agreement Proposal and approvals with respect to certain other related matters. This proxy statement/prospectus, which you should read carefully, contains important information about the Merger and other matters being considered at the Special Meeting.

This document is being delivered to you as both a proxy statement of XTO EnergyPioneer and a prospectus of ExxonMobil in connection with the merger.Merger. It is the proxy statement by which the XTO EnergyPioneer board of directors (the “Pioneer board”) is soliciting proxies from youPioneer stockholders to vote on the adoption of the merger agreement at the special meetingSpecial Meeting, or at any adjournment or postponement of the special meeting. ItSpecial Meeting, on the approval of the Merger Agreement Proposal and the approval of the Advisory Compensation Proposal, each as described more fully herein. In addition, this document is also the prospectus by which ExxonMobil will issue shares of ExxonMobil common stock to youPioneer stockholders in the merger.Merger in accordance with the Merger Agreement.

Your vote is important regardless of the amount of shares of Pioneer common stock that you own. We encourage you to vote as soon as possible.

Q: What is the purpose of the Special Meeting?

A: At the Special Meeting, holders of Pioneer common stock will act upon all the matters outlined in the Notice of Special Meeting of Stockholders. These include:

Q: What is a proxy and how does it work?

A: The Pioneer board is asking for your proxy. A “proxy” is your legal designation of another person to vote the stock you own in the manner you direct. If you designate someone as your proxy in a written document, that document is also called a proxy or a proxy card. By giving your proxy to the persons named as proxy holders in

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the proxy card accompanying this proxy statement/prospectus, you authorize them to vote your shares of Pioneer common stock at the Special Meeting in the manner you direct. You may cast votes “FOR,” “AGAINST” or “ABSTAIN” with respect to both, either or neither of the matters we are submitting to a vote of holders of Pioneer common stock at the Special Meeting.

If you complete and submit your proxy in one of the manners described below, but do not specify how to vote, the proxy holders will vote your shares “FOR” each of the proposals described below.

Q: What will Pioneer stockholders receive for their shares of Pioneer common stock in the Merger?

A: At the effective time of the Merger (the “effective time”), each share of Pioneer common stock issued and outstanding immediately prior to the effective time (including the unvested restricted stock of Pioneer, but excluding shares of Pioneer common stock held (1) in treasury (excluding Pioneer common stock subject to or issuable in connection with a Pioneer employee benefit plan) or (2) by ExxonMobil or Merger Sub, which are to be cancelled at the effective time (collectively, the “excluded shares”)) will be converted into the right to receive 2.3234 shares of ExxonMobil common stock (the “share consideration”). No fractional shares of ExxonMobil common stock will be delivered to any holder of shares of Pioneer common stock upon completion of the Merger. Instead, all fractional shares of ExxonMobil common stock that a holder of shares of Pioneer common stock would otherwise be entitled to receive as a result of the Merger will be aggregated and, if a fractional share results from such aggregation, such holder will be entitled to receive the cash proceeds from the sale of such fractional share by the exchange agent for the account of such holder (together with the share consideration, the “Merger Consideration”), without interest and subject to any applicable withholding taxes, in accordance with the Merger Agreement.

Although the number of shares of ExxonMobil common stock that Pioneer stockholders will receive in the Merger is fixed, the market value of the Merger Consideration will fluctuate with the market price of ExxonMobil common stock and will not be known at the time that holders of Pioneer common stock vote to adopt the Merger Agreement. Based on the closing price of $72.83 for ExxonMobilExxonMobil’s common stock on the New York Stock Exchange (“NYSE”) on December 11, 2009,October 5, 2023, the last trading day beforeprior to media reports that Pioneer and ExxonMobil were in merger discussions, the public announcement of the merger agreement, the merger consideration2.3234 exchange ratio represented approximately $51.69$253.23 in implied value for each share of XTO EnergyPioneer common stock. Based on theExxonMobil’s closing price on [                ], 2023 of $68.61 for ExxonMobil common stock on$[        ], the New York Stock Exchange on April 14, 2010, the most recent practicable trading day prior to the date of this proxy statement/prospectus, the merger consideration2.3234 exchange ratio represented approximately $48.70$[        ] in implied value for each share of XTO EnergyPioneer common stock.The market price of ExxonMobil common stock will fluctuate prior to the merger, and the market price of ExxonMobil common stock when received by XTO EnergyPioneer stockholders receive those shares after the mergerMerger is completed could be greater orthan, less than or the currentsame as the market price of shares of ExxonMobil common stock. See “Risk Factors” beginningstock on page [—]the date of this proxy statement/prospectus.

connection with the merger. Instead, XTO Energy will remain an independent public company and its common stock will continue to be listed and traded on the New York Stock Exchange. If the merger agreement is terminated under specified circumstances, XTO Energy may be required to pay ExxonMobil a termination fee of $900 million as described under “The Merger Agreement—Termination Fee Payable by XTO Energy” beginning on page [—] of this proxy statement/prospectus.

Q: If I am a holder of Pioneer common stock, how will I receive the Merger Consideration to which I am entitled?

A: The approvalconversion of Pioneer common stock into the right to receive the Merger Consideration will occur automatically upon the completion of the Merger. Promptly after the effective time and in any event within five business days of the completion of the Merger, an exchange agent will mail to each holder of record of Pioneer common stock (whose shares were converted into the right to receive the Merger Consideration pursuant to the Merger Agreement) a letter of transmittal and instructions for use in effecting the surrender of certificates representing shares of Pioneer common stock (“Certificates”) and book-entry shares representing shares of Pioneer common stock (“Uncertificated Shares”) in exchange for the Merger Consideration and any dividends or other distributions to which such Certificates or Uncertificated Shares become entitled to pursuant to the Merger Agreement.

Upon receipt by the exchange agent of (i) either Certificates or Uncertificated Shares and (ii) a duly completed and validly executed letter of transmittal, and such other documents as may be required pursuant to

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the instructions in the letter of transmittal and otherwise by the exchange agent, the holder of such Certificates or Uncertificated Shares will be entitled to receive the Merger Consideration in exchange therefor.

Q: Who will own ExxonMobil common stock immediately following the transactions?

A: ExxonMobil and Pioneer estimate that, as of immediately following completion of the Merger and without giving effect to any ExxonMobil share repurchases after the date of this proxy statement/prospectus, holders of ExxonMobil common stock as of immediately prior to the Merger will hold approximately [    ]% and holders of Pioneer common stock as of immediately prior to the Merger will hold approximately [    ]% of the outstanding shares of ExxonMobil common stock (or, on a fully diluted basis, holders of ExxonMobil common stock as of immediately prior to the Merger will hold approximately [    ]% and holders of Pioneer common stock as of immediately prior to the Merger will hold approximately [    ]% of the shares of ExxonMobil common stock).

Q: How important is my vote?

A: Your vote “FOR” each proposal presented at the Special Meeting is very important regardless of the number of shares of Pioneer common stock that you own, and you are encouraged to adoptsubmit a proxy or proxies as soon as possible.

Q: What vote is required to approve each proposal at the mergerSpecial Meeting?

A: Approval of the Merger Agreement Proposal requires the affirmative vote of holders of a majority in voting power of the outstanding shares of Pioneer common stock entitled to vote on the Merger Agreement Proposal. Any abstention by a holder of Pioneer common stock or the failure of any holder of Pioneer common stock to submit a vote will have the same effect as voting “AGAINST” the Merger Agreement Proposal.

Approval of the Advisory Compensation Proposal requires the affirmative vote of the majority of the voting power present (via the Pioneer meeting website) or represented by proxy and entitled to vote on such proposal. Abstentions from voting by a Pioneer stockholder attending the Special Meeting via the Pioneer meeting website or voting by proxy will have the same effect as a vote “AGAINST” the Advisory Compensation Proposal. A failure to attend the Special Meeting via the Pioneer meeting website or by proxy will have no effect on the outcome of the vote on the Advisory Compensation Proposal. Because the Advisory Compensation Proposal is non-binding, if the Merger Agreement is adopted by Pioneer stockholders and the Merger is completed, the compensation that is the subject of the Advisory Compensation Proposal, including amounts Pioneer is contractually obligated to pay, would still be paid regardless of the outcome of the non-binding advisory vote.

See “The Pioneer Special Meeting—Vote Required” beginning on page 45 of this proxy statement/prospectus.

Q: How does the Pioneer board recommend that I vote?

A: At a meeting held on October 10, 2023, the Pioneer board unanimously (i) determined that the Merger Agreement and the transactions contemplated thereby, including the Merger, are fair to and in the best interests of Pioneer and its stockholders, (ii) approved, adopted and declared advisable the Merger Agreement and the transactions contemplated thereby, including the Merger, in accordance with the requirements of the DGCL and (iii) resolved to recommend adoption of the Merger Agreement by the stockholders of Pioneer.

Accordingly, the Pioneer board unanimously recommends that holders of Pioneer common stock vote “FOR” the Merger Agreement Proposal and “FOR” the Advisory Compensation Proposal.

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Q: Are there any Pioneer stockholders who have already committed to voting in favor of the Merger Agreement Proposal at the Special Meeting?

A: On [            ], Pioneer’s directors and executive officers had the right to vote approximately [            ] shares of the then-outstanding Pioneer common stock, collectively representing approximately [    ]% of the Pioneer common stock outstanding and entitled to vote on that date. We currently expect that Pioneer’s directors and executive officers will vote their shares “FOR” the Merger Agreement Proposal and “FOR” the Advisory Compensation Proposal, although no director or executive officer has entered into any agreement by XTO Energy stockholdersobligating him or her to do so.

Q: Will the ExxonMobil common stock received at the time of completion of the Merger be traded on an exchange?

A: Yes. It is a condition to the obligationsconsummation of XTO Energythe Merger that the shares of ExxonMobil common stock to be issued to Pioneer stockholders in connection with the Merger be authorized for listing on the NYSE, subject to official notice of issuance.

Q: How will ExxonMobil shareholders be affected by the Merger?

A: Upon completion of the Merger, each ExxonMobil shareholder will hold the same number of shares of ExxonMobil stock that such shareholder held immediately prior to completion of the Merger. As a result of the Merger, ExxonMobil shareholders will own shares in a larger consolidated company with more assets. However, because ExxonMobil will be issuing additional shares of ExxonMobil common stock to Pioneer stockholders in exchange for their shares of Pioneer common stock in connection with the Merger, each outstanding share of ExxonMobil common stock, as of immediately prior to the Merger, will represent a smaller percentage of the aggregate number of shares of ExxonMobil common stock outstanding after the Merger.

Q: What are the U.S. federal income tax consequences of the Merger to holders of Pioneer common stock?

A: The Merger is intended to qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended (the “Code”), and ExxonMobil and Pioneer intend to report the Merger consistent with such qualification. Each of ExxonMobil and Pioneer has agreed in the Merger Agreement to use its best efforts (i) to cause the Merger to qualify as a “reorganization” within the meaning of Section 368(a) of the Code and (ii) not to, and not to permit or cause any of its respective subsidiaries or affiliates to, take or cause to be taken, or fail to take or cause to be taken any action, which action, failure or cessation, could reasonably be expected to cause the Merger to fail to or cease to qualify as a “reorganization” within the meaning of Section 368(a) of the Code for U.S. federal income tax purposes. Although each of Pioneer and ExxonMobil expects to receive a tax opinion from its counsel, Gibson, Dunn & Crutcher LLP (“Gibson Dunn”) and Davis Polk & Wardwell LLP (“Davis Polk”), respectively, to the effect that the Merger will qualify as a reorganization for U.S. federal income tax purposes, the receipt of a tax opinion from counsel is not a condition to either party’s obligation to complete the merger.Merger. ExxonMobil and Pioneer have not sought, and do not intend to seek, any ruling from the U.S. Internal Revenue Service (the “IRS”) regarding the qualification of the Merger as a “reorganization” within the meaning of Section 368(a) of the Code. Assuming that the Merger qualifies as a “reorganization” within the meaning of Section 368(a) of the Code, U.S. holders (as defined in “U.S. Federal Income Tax Consequences of the Merger”) generally will not recognize gain or loss for U.S. federal income tax purposes, except with respect to cash proceeds from the sale of fractional shares of ExxonMobil common stock. If the Merger does not qualify as a “reorganization,” the Merger generally would be a taxable transaction to U.S. holders, and each U.S. holder generally would recognize gain or loss in an amount equal to the difference, if any, between (i) the sum of the fair market value of the ExxonMobil common stock it receives in the Merger plus the amount of any cash proceeds from the sale of fractional shares of ExxonMobil common stock and (ii) such holder’s adjusted tax basis in its shares of Pioneer common stock exchanged in the Merger.

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The U.S. federal income tax consequences described above may not apply to all holders of Pioneer common stock. You should read “U.S. Federal Income Tax Consequences of the Merger” beginning on page 104 of this proxy statement/prospectus for a more complete discussion of the U.S. federal income tax consequences of the Merger. Tax matters can be complicated and the tax consequences of the Merger to you will depend on your particular tax situation. You should consult your tax advisor to determine the tax consequences of the Merger to you.

Q: When do ExxonMobil and Pioneer expect to complete the Merger?

A: ExxonMobil and Pioneer currently expect to complete the Merger in the first half of 2024, subject to timing of satisfaction of closing conditions to the Merger. However, neither ExxonMobil nor Pioneer can predict the actual date on which the Merger will be completed, nor can the parties provide any assurance that the Merger will be completed. See “Risk Factors,” “The Merger—Regulatory Approvals Required for the Merger” and “The Merger Agreement—Conditions to Completion of the Merger” beginning on pages 29, 74, and 83, respectively, of this proxy statement/prospectus.

Q: Is the completion of the Merger subject to any conditions?

A: Yes. ExxonMobil, Merger Sub and Pioneer are not required to complete the Merger unless certain conditions are satisfied (or, to the extent permitted by applicable law, waived). These conditions include, among others, the adoption of the Merger Agreement by holders of a majority of Pioneer common stock and the expiration or termination of any applicable waiting period, or any extension thereof, under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (the “HSR Act”) (in the case of ExxonMobil’s obligation to complete the Merger, without the imposition of a Burdensome Condition (see “The Merger Agreement—Reasonable Best Efforts Covenant” beginning on page 95 of this proxy statement/prospectus)). For a more complete summary of the conditions that must be satisfied (or, to the extent permitted by applicable law, waived) prior to completion of the Merger, see “The Merger Agreement—Conditions to Completion of the Merger” and “The Merger—Regulatory Approvals Required for the Merger” beginning on pages 83 and 74, respectively, of this proxy statement/prospectus.

Q: What happens if the Merger is not completed?

A: In the event that the Merger Agreement is not adopted by Pioneer’s stockholders at the Special Meeting or the Merger is not completed for any other reason, Pioneer’s stockholders will not receive any consideration for shares of Pioneer stock they own. Instead, Pioneer will remain an independent public company, Pioneer common stock will continue to be listed and traded on the NYSE and registered under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and Pioneer will continue to file periodic reports with the Securities and Exchange Commission (the “SEC”) on account of Pioneer’s common stock. If the Merger is not completed for any reason, including as a result of Pioneer stockholders failing to approve the Merger Agreement Proposal, the ongoing businesses of Pioneer may be adversely affected, and the anticipated benefits of having completed the Merger will not be realized. See “Risk Factors—Failure to complete the Merger could negatively impact the stock price and the future business and financial results of Pioneer” beginning on page 35 of this proxy statement/prospectus.

Under specified circumstances, Pioneer may be required to pay a termination fee upon termination of the Merger Agreement, as described under “The Merger Agreement—Termination of the Merger Agreement” beginning on page 101 of this proxy statement/prospectus.

Q: When and where is the Special Meeting?

A: The Special Meeting will be a virtual only meeting conducted exclusively via live webcast at www.virtualshareholdermeeting.com/[    ] starting at [                ] Central Time (with log-in beginning at

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[                ] Central Time) on [                ]. You will be able to attend the Special Meeting and vote your shares electronically during the meeting by going to www.virtualshareholdermeeting.com/[    ] and entering the 16-digit control number included on the proxy card or voting instruction form that you received. Because the Special Meeting is completely virtual and being conducted via live webcast, stockholders will not be able to attend the meeting in person.

Q: Who can vote at, and what is the record date of, the Special Meeting?

A: All Pioneer stockholders who hold shares of Pioneer common stock of record at the close of business on [            ], 2023, the record date for the Special Meeting (the “Pioneer record date”), are entitled to receive notice of, and to vote, at the Special Meeting.

Q: How many votes may I cast?

A: Each issued and outstanding share of Pioneer common stock entitles its holder of record to one vote on each matter to be considered at the 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 Special Meeting or any adjournments or postponements thereof.

Q: What constitutes a quorum at the Special Meeting?

A: In order for business to be conducted at the Special Meeting, a quorum must be present. A quorum at the 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 Special Meeting.

For purposes of determining whether there is a quorum, all shares that are present will count towards the quorum, which will include proxies received but marked as abstentions and will exclude broker non-votes. Broker non-votes occur when a beneficial owner holding shares in “street name” does not instruct the broker, bank or other nominee that is the record owner of such stockholder’s shares on how to vote those shares on a particular proposal.

Q: What do I need to do now?

A: After you have carefully read and considered the information contained in or incorporated by reference into this proxy statement/prospectus, please submit your proxy via the internet or by telephone in accordance with the instructions set forth on the enclosed proxy card or voting instruction form you received, or complete, sign, date and return the enclosed proxy card or voting instruction form in the self-addressed, stamped envelope provided as soon as possible so that your shares will be represented and voted at the Special Meeting.

Additional information on voting procedures can be found under “The Pioneer Special Meeting” beginning on page 42 of this proxy statement/prospectus.

Q: How will my proxy be voted?

A: If you submit your proxy via the internet, by telephone or by completing, signing, dating and returning the enclosed proxy card or voting instruction form, your proxy will be voted in accordance with your instructions. If you sign your proxy card and return it without indicating how you would like to vote your shares, your proxy card will be voted in accordance with the recommendation of the Pioneer board.

Additional information on voting procedures can be found under “The Pioneer Special Meeting” beginning on page 42 of this proxy statement/prospectus.

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Q: Who will count the votes?

A: The votes at the Special Meeting will be counted by an individual designated by the Pioneer board to serve as inspector of election.

Q: How do I vote my shares if I am a stockholder of record?

A: Pioneer stockholders of record at the close of business on [            ] may vote in one of the following ways:

Q:	When is this proxy statement/prospectus being mailed?

If you submitare a proxy by telephonebeneficial holder of Pioneer common stock, you are invited to attend the Special Meeting; however, because you are not a stockholder of record, you may not vote your shares at the Special Meeting unless you receive a voting instruction form with a 16-digit control number from your bank, broker or other nominee that is the Internet web site, please do not returnstockholder of record with respect to your shares of Pioneer common stock.

Q: How can I vote during the Special Meeting?

A: All stockholders of record may vote online during the Special Meeting. Street name holders may vote online during the Special Meeting if they have a voting instruction form with a 16-digit control number, as described below. You may cast your vote electronically during the Special Meeting using the 16-digit control number found on your proxy card or voting instruction form. If you do not have a control number, please contact your broker, bank or other nominee as soon as possible so that you can be provided with a control number.

Whether you plan to attend the Special Meeting or not, we encourage you to vote by mail.proxy as soon as possible.

SeeQ: How can I submit a question at the responseSpecial Meeting?

A: Stockholders attending the Special Meeting will be in a listen-only mode and will not be able to speak during the next questionwebcast. However, stockholders will be able to submit any questions by the close of business on [            ] in advance of the Special Meeting by visiting [            ].

Q: Who do I contact if I am encountering difficulties attending the Special Meeting online?

A: If you encounter any difficulties during the check-in process or during the Special Meeting, please call [            ], and a technician will be ready to assist you starting at [            ] Central Time and until the Special

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Meeting has finished. Please give yourself sufficient time to log-in and ensure you can hear the streaming audio before the meeting starts.

Q: What should I do if I receive more than one set of voting materials for the Special Meeting?

A: You may receive more than one set of voting materials for the Special Meeting, including multiple copies of this proxy statement/prospectus and multiple proxy cards or voting instruction forms. For example, if you hold your shares of Pioneer common stock in more than one brokerage account, you will receive a separate voting instruction form for each brokerage account in which you hold shares. If you are a holder of record of Pioneer common stock and your shares are registered in more than one name, you will receive more than one proxy card. Please submit each separate proxy or voting instruction form that you receive by following the instructions set forth in each separate proxy or voting instruction form. If you fail to submit each separate proxy or voting instruction form that you receive, not all of your shares will be voted.

Q: What’s the difference between holding shares as a stockholder of record and holding shares as a beneficial owner?

A: If your shares of Pioneer common stock are registered directly in your name with Pioneer’s transfer agent, Continental Stock Transfer & Trust Company, you are considered, with respect to those shares, to be the stockholder of record. If you are a stockholder of record, then this proxy statement/prospectus and your proxy card have been sent directly to you by Pioneer.

If your shares of Pioneer common stock are held through a bank, broker or other nominee, you are considered the beneficial owner of shares of Pioneer common stock held in “street name.” In that case, this proxy statement/prospectus has been forwarded to you by your bank, broker or other nominee who is considered, with respect to those shares, to be the stockholder of record. As the beneficial owner, you have the right to direct your bank, broker or other nominee how to vote your shares held throughby following their instructions for voting, and you are also invited to attend the Special Meeting. But, because you are not the stockholder of record, you may not vote your shares at the Special Meeting unless you receive a voting instruction form with a 16-digit control number from your bank, broker or other nominee.

Q: If my shares are held in “street name” by my broker, bank or other nominee, will my broker, bank or other nominee automatically vote my shares for me?

A: No. If your shares are held in the name of a broker, bank or other nominee, you do not provide votingwill receive separate instructions tofrom your broker, bank or other nominee describing how to vote your sharesshares. The availability of the Internet or telephonic voting will not be voteddepend on any proposal on whichyour broker’s, bank’s or other nominee’s voting process. Please check with your broker, bank or other nominee and follow the voting procedures provided by your broker, bank or other nominee on your voting instruction form.

You should instruct your broker, bank or other nominee how to vote your shares. Under the rules applicable to broker-dealers, your broker, bank or other nominee has discretionary authority to vote on proposals that are considered routine but does not have discretionary authority to vote. This is called a broker non-vote. In these cases, the broker can registervote your shares as being presenton proposals that are considered non-routine, and each of the proposals to be voted on at the special meeting for purposes of determiningSpecial Meeting is considered non-routine. As a quorum, butresult, no broker will not be ablepermitted to vote your shares at the Special Meeting without receiving instructions from you. A so-called “broker non-vote” results when banks, brokers and other nominees return a valid proxy but do not vote on those matters for which specific authorization is required. Under the current rules of the New York Stock Exchange, brokersa particular proposal because they do not have discretionary authority to vote on the proposal to adoptmatter and have not received specific voting instructions from the merger agreement.Abeneficial owner of such shares.

Therefore, if you are a Pioneer stockholder whose shares of common stock are held in street name and you do not instruct your broker, non-vote will have the same effect as a vote “AGAINST” adoption of the merger agreement.

If you hold shares through a brokerbank or other nominee and wishon how to vote your shares in person at the special meeting, you must obtain a proxy from your broker or other nominee and present it to the inspector of election with your ballot when you vote at the special meeting.shares:

Q:	How will my shares be represented at the special meeting?

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A quorum at the 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 Special Meeting. For purposes of determining whether there is a quorum, all shares that are present will count towards the quorum, which will include proxies received but marked as abstentions and will exclude broker non-votes.

Additional information on voting procedures can be found under “The Pioneer Special Meeting” beginning on page 42 of this proxy statement/prospectus.

Q: What do I do if I am a Pioneer stockholder and I want to revoke my proxy?

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

If you hold youra 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 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 [    ]. Alternatively, a Pioneer stockholder may also revoke their proxy by attending the Special Meeting virtually, using his, her or its unique 16-digit control number and voting his, her or its shares online during the meeting.

Additional information can be found under “The Pioneer Special Meeting” beginning on page 42 of this proxy statement/prospectus.

Q: What happens if I sell or otherwise transfer my shares of Pioneer common stock before the Special Meeting?

A: The Pioneer record date is prior to the date of the Special Meeting. If you must followsell or otherwise transfer your shares of Pioneer common stock after the directionsPioneer record date but before the Special Meeting, unless special arrangements (such as provision of a proxy) are made between you receive fromand the person to whom you transfer your broker or other nomineeshares of Pioneer common stock, you will retain your right to vote such shares at the Special Meeting but will otherwise transfer ownership of and the economic interest in order to revoke or change your voting instructions.shares of Pioneer common stock.

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Q: What happens if I sell or otherwise transfer my shares of Pioneer common stock before the completion of the Merger?

Q:	What do I do if I receive more than one set of voting materials?

A: Only holders of shares of Pioneer common stock at the effective time will become entitled to receive the Merger Consideration. If you sell your shares of Pioneer common stock prior to the completion of the Merger, you will not be entitled to receive the Merger Consideration by virtue of the Merger.

Q: Do any of the officers or directors of Pioneer have interests in the Merger that may differ from or be in addition to my interests as a Pioneer stockholder?

A: In considering the recommendation of the Pioneer board that Pioneer stockholders vote to approve the Merger Agreement Proposal and to approve the Advisory Compensation Proposal, Pioneer stockholders should be aware that Pioneer’s directors and executive officers have interests in the Merger that may be different from, or in addition to, the interests of Pioneer stockholders generally. These interests may include, among others:

The Pioneer board was aware of and considered these potential interests, among other matters, in evaluating and negotiating the Merger Agreement and the transactions contemplated thereby, in approving the Merger and in recommending the adoption of the Merger Agreement and the approval of the Advisory Compensation Proposal.

For more information and quantification of these interests, see “Interests of Pioneer’s Directors and Executive Officers in the Merger” beginning on page 107 of this proxy statement/prospectus.

Q: Where can I find voting results of the Special Meeting?

A: Pioneer intends to announce preliminary voting results at the Special Meeting and publish the final results in a Current Report on Form 8-K that will be filed with the SEC following the Special Meeting. All reports that Pioneer and ExxonMobil file with the SEC are publicly available when filed. See “Where You Can Find More Information” beginning on page 143 of this proxy statement/prospectus.

Q: Do Pioneer stockholders have dissenters’ or appraisal rights?

A: Pioneer stockholders are not entitled to dissenters’ or appraisal rights in connection with the Merger. See “The Merger—No Dissenters’ or Appraisal Rights” beginning on page 76 of this proxy statement/prospectus.

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Q: How can I find more information about ExxonMobil and Pioneer?

A: You can find more information about ExxonMobil and Pioneer from various sources described in “Where You Can Find More Information” beginning on page 143 of this proxy statement/prospectus.

Q: Who can answer any questions I may have about the Special Meeting, the Merger or the transactions contemplated by the Merger Agreement?

A: If you have any questions about the Special Meeting, the Merger or the other transactions contemplated by the Merger Agreement or how to submit your proxy, or if you need additional copies of this proxy statement/prospectus or documents incorporated by reference herein, the enclosed proxy card in the accompanying postage-paid envelope;or voting instructions, you should contact Pioneer or Pioneer’s proxy solicitor:

attending the special meeting and voting by ballot in person.

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