As filed with the Securities and Exchange Commission on April 20, 2010September 27, 2023

Registration No. 333-164620333-274252

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

AMENDMENT NO. 2Amendment No. 1

TOto

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 InvestmentEMPF Corporation, (“Merger Sub”), a wholly owned subsidiary of Exxon Mobil Corporation, (“ExxonMobil”), with and into XTO EnergyDenbury 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.

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. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Securities Exchange Act of 1934 (the “Exchange Act”).1934.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

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, 2010SEPTEMBER 27, 2023

MERGER PROPOSAL —

TRANSACTION PROPOSED—YOUR VOTE IS VERY IMPORTANT

[—], 2010

Dear XTO EnergyStockholders of Denbury Inc. Stockholder::

On DecemberJuly 13, 2009, XTO Energy2023, Denbury Inc. and(“Denbury”), Exxon Mobil Corporation entered into a merger agreement that provides for XTO Energy to become(“ExxonMobil”) and EMPF Corporation, a wholly owned subsidiary of ExxonMobil. The XTO EnergyExxonMobil (“Merger Sub”), entered into an Agreement and Plan of Merger (the “Merger Agreement”), under which, upon the terms and subject to the conditions set forth therein, Merger Sub will merge with and into Denbury, with Denbury surviving as a wholly owned subsidiary of ExxonMobil (the “Merger”).

If the Merger is completed, Denbury stockholders will receive, in exchange for each share of Denbury common stock, par value $0.001 per share, held immediately prior to the Merger, 0.840 of a share of ExxonMobil common stock, without par value (such consideration, the “Merger Consideration”).

Denbury’s board of directors has determined that the merger and the merger agreement are advisable and in the best interests of XTO Energy and its stockholders and hasunanimously approved the merger agreementMerger Agreement and recommends that Denbury stockholders vote in favor of approving and adopting the merger.Merger Agreement.

IfBased on ExxonMobil’s closing stock price on     , 2023, the merger is completed, each outstandingmost recent practicable date for which such information was available, the Merger Consideration represented approximately $   in value per share of XTO Energy common stock will be converted into 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 outstanding shares of ExxonMobil common stock, basedwhich represents a premium of approximately   % over the closing price of the Denbury common stock on July 12, 2023, the numberlast trading day before the public announcement of sharesthe execution of XTO Energy andthe Merger Agreement with ExxonMobil. The value of the Merger Consideration to be received in exchange for each share of Denbury 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 Denbury common stock of each of ExxonMobil and XTO Energy is tradedlisted on theThe New York Stock Exchange (the “NYSE”) under the symbolssymbol “DEN”. The ExxonMobil common stock is listed on the NYSE under the symbol “XOM” and “XTO”, respectively..

We are holding a special meetingThe Merger cannot be completed without approval of stockholders on [—], 2010 at [—], local time, at [—], to obtain your votethe proposal to adopt the merger agreement. YourMerger Agreement by the affirmative vote is very important. The merger cannot be completed unless theof holders of a majority of the outstanding shares of XTO EnergyDenbury common stock entitled to vote forthereon. Because of this, Denbury is holding a special meeting of its stockholders on    , 2023 (the “Special Meeting”) to vote on the adoption ofproposal necessary to complete the merger agreementMerger. Information about the Special Meeting, the Merger, the Merger Agreement and the other business to be considered by stockholders at the special meeting.

The XTO EnergySpecial Meeting is contained in this proxy statement/prospectus. Denbury’s board of directors has fixed the close of business on September 27, 2023 as the record date for the determination of Denbury stockholders entitled to notice of, and to vote at, the Special Meeting. Any stockholder entitled to attend and vote at the Special Meeting is entitled to appoint a proxy to attend and vote on such stockholder’s behalf. Such proxy need not be a holder of Denbury common stock. 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 page31.

The Denbury board of directors has unanimously determined that the Merger Agreement and the transactions contemplated thereby, including the Merger, are fair to and in the best interests of Denbury 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 and directed that the Merger Agreement be submitted to the Denbury stockholders for adoption at a meeting of such stockholders. The Denbury board of directors unanimously recommends that XTO EnergyDenbury stockholders vote “FOR” the adoptionproposal to approve and adopt the Merger Agreement and the transactions contemplated thereby, including the Merger.

Your vote is very important regardless of the merger agreement.number of shares of Denbury 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,

Christian S. Kendall

Bob R. SimpsonPresident and Chief Executive Officer

Chairman of the Board and FounderDenbury Inc.

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    [—], 20102023, and is first being mailed to the stockholders of XTO EnergyDenbury on or about    [—], 2010.2023.

ADDITIONAL INFORMATION

The accompanying document is the proxy statement of XTO Energy Inc.Denbury 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 Denbury stockholders as consideration forin the merger.Merger. The accompanying proxy statement/prospectus incorporates by reference important business and financial information about Exxon Mobil CorporationDenbury 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 CorporationDenbury 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 Denbury common stock, please contact Denbury’s proxy solicitor:

Innisfree M&A Incorporated the proxy solicitor for XTO Energy Inc., toll-free at

501 Madison Avenue, 20^th Floor

New York, New York 10022

Stockholders May Call Toll-Free: (877) 750-5836 (banks and brokers call collect at717-3905

Banks & Brokers May Call Collect: (212) 750-5833). You will not be charged for any of these documents that you request.750-5833

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   , 2023).

See “Where You Can Find More Information” beginning on page [—]178 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    , 2023

To theour Stockholders:

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

Notice is hereby given that a special meeting of stockholders of XTO Energy Inc., which is referred to as XTO Energy, a Delaware corporation (“Denbury”), will be held virtually at www.virtualshareholdermeeting.com/DEN2023SM at     Central Time (CT) on     [—], 2010 at [—], local time, at [—], solely2023, 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 the close of business on [—], 2010September 27, 2023 are entitled to notice of, the XTO Energy special meeting and to vote at, the XTO Energy specialSpecial Meeting.

To be admitted to the Special Meeting at www.virtualshareholdermeeting.com/DEN2023SM, stockholders must enter the control number found on their proxy card, voting instruction form or notice. Once properly admitted to the Special Meeting, stockholders of record as of the record date may vote their shares by following the instructions available on the meeting or at any adjournment or postponement thereof. Awebsite during the meeting and may also view the complete list of stockholders entitled to vote at the special meetingannual meeting. To ask a question pertaining to the business of the Special Meeting, stockholders must submit it in advance of the Special Meeting by visiting www.proxyvote.com. Questions may be submitted until 11:59 p.m., Central Time, on  , 2023. Each stockholder will be limited to no more than one question. Technical support will be available in our offices locatedon the meeting platform at    810 Houston Street, Fort Worth, Texas 76102, during regular business hours for a period of no less than ten days beforebeginning at    a.m. Central Time on    , 2023 or by calling (800) 586-1548 (US) or (303) 562-9288 (International). The technical support offered through this service is designed to address difficulties related to the specialvirtual meeting website, and at the placeit is recommended that you contact your broker should you be unable to locate your control number.

Completion of the special meeting during the meeting.

AdoptionMerger is conditioned on adoption of the merger agreementMerger Agreement by the XTO EnergyDenbury stockholders, is a condition to the merger andwhich requires the affirmative vote of holders of a majority of the outstanding shares of XTO EnergyDenbury common stock outstanding and entitled to vote thereon. Therefore, your

The Denbury board of directors has unanimously determined that the Merger Agreement and the transactions contemplated thereby, including the Merger, are fair to and in the best interests of Denbury 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 and directed that the Merger Agreement be submitted to the Denbury stockholders for adoption at a meeting of such stockholders. The Denbury board of directors unanimously recommends that Denbury stockholders vote “FOR” the proposal to approve and adopt the Merger Agreement and the transactions contemplated thereby, including the Merger.

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 Denbury 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 Denbury 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 31.

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 EnergyDenbury common stock, please contact XTO Energy’sDenbury’s proxy solicitor:

Innisfree M&A Incorporated at (877) 717-3905.

501 Madison Avenue, 20th FloorBy order of the Board of Directors,

New York, New York 10022James S. Matthews

Stockholders, call toll-free: (877) 750-5836Executive Vice President, Chief Administrative Officer,

BanksGeneral Counsel 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,Denbury, may have regarding the mergerMerger and other matters being considered at the special meeting of Denbury 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, Denbury 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 178 of this proxy statement/prospectus.

Q: Why am I receiving this document?

A: Exxon Mobil Corporation, a New Jersey corporation (“ExxonMobil”), EMPF Corporation, a wholly owned subsidiary of ExxonMobil (“Merger Sub”), and Denbury Inc., a Delaware corporation (“Denbury”), have entered into an Agreement and Plan of Merger, dated as of July 13, 2023 (as it may be amended from time to time, the “Merger Agreement”), providing for the merger of Merger Sub with and into Denbury (the “Merger”), with Denbury surviving the Merger as a wholly owned subsidiary of ExxonMobil. In order to complete the Merger, Denbury stockholders must approve the proposal to adopt the Merger Agreement and all other conditions to the Merger must be satisfied or waived.

Denbury 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 EnergyDenbury and a prospectus of ExxonMobil in connection with the merger.Merger. It is the proxy statement by which the XTO EnergyDenbury board of directors is soliciting proxies from youDenbury 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 youDenbury stockholders in the merger.Merger in accordance with the Merger Agreement.

Your vote is important regardless of the amount of shares of Denbury 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 Denbury 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 Denbury board of directors 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 the proxy card accompanying this proxy statement/prospectus, you authorize them to vote your

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shares of Denbury common stock, $0.001 par value per share, at the Special Meeting in the manner you direct. You may cast votes “FOR,” “AGAINST” or “ABSTAIN” with respect to all, some or none of the matters we are submitting to a vote of holders of Denbury 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 Denbury stockholders receive for their shares of Denbury common stock in the Merger?

A: At the effective time of the Merger (the “effective time”), each share of Denbury common stock issued and outstanding immediately prior to the effective time (including the unvested restricted stock of Denbury, but excluding shares of Denbury common stock held (1) in treasury (excluding Denbury common stock subject to or issuable in connection with a Denbury 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 0.840 shares of ExxonMobil common stock (the “share consideration”). No fractional shares of ExxonMobil common stock will be issued and each Denbury stockholder who would otherwise have been entitled to receive a fraction of a share of ExxonMobil common stock in connection with the Merger shall receive in lieu thereof a cash payment (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 Denbury 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 Denbury 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,July 12, 2023, the last trading day before the public announcement of the merger agreement,Merger, the merger consideration0.840 exchange ratio represented approximately $51.69$89.45 in implied value for each share of XTO EnergyDenbury 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 consideration0.840 exchange ratio represented approximately $48.70$   in implied value for each share of XTO EnergyDenbury 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 EnergyDenbury 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 Denbury common stock, how will I receive the Merger Consideration to which I am entitled?

A: The approvalconversion of Denbury 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 (5) business days of the completion of the Merger, an exchange agent will mail to each holder of record of Denbury 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 Denbury common stock (“Certificates”) and book-entry shares representing shares of Denbury 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 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 Denbury estimate that, as of immediately following completion of the Merger, holders of ExxonMobil common stock as of immediately prior to the Merger will hold approximately   % and holders of

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Denbury 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 Denbury 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 Denbury 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 Denbury common stock, at the Special Meeting present (via the Denbury meeting website) or by proxy, entitled to vote on the Merger Agreement proposal. Any abstention by a holder of Denbury common stock and the failure of any holder of Denbury common stock to submit a vote will have the same effect as voting “AGAINST” the Merger Agreement proposal.

Adoption of the Advisory Compensation Proposal requires the affirmative vote of the majority of the voting power present (via the Denbury meeting website) or represented by proxy and entitled to vote on such proposal. Abstentions from voting by a Denbury stockholder attending the Special Meeting via the Denbury 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 Denbury 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 approved by Denbury stockholders and the Merger is completed, the compensation that is the subject of the Advisory Compensation Proposal, including amounts Denbury is contractually obligated to pay, would still be paid regardless of the outcome of the non-binding advisory vote.

See “The Special Meeting—Required Vote; Treatment of Abstentions and Broker Non-Votes” beginning on page 45 of this proxy statement/prospectus.

Q: How does the Denbury board of directors recommend that I vote?

A: Denbury’s board of directors, after considering the various factors described under “The Merger—Recommendation of the Denbury Board of Directors and Reasons for the Merger” beginning on page 73 of this proxy statement/prospectus, the comprehensive process conducted by the Denbury board of directors and the alternatives to the Merger (including Denbury remaining as a standalone company), unanimously (i) determined that it is in the best interests of Denbury and its stockholders, and declared it advisable, for Denbury to enter into the Merger Agreement, (ii) approved the execution, delivery and performance by Denbury of the Merger Agreement and the consummation of the transactions contemplated thereby, including the Merger, and (iii) resolved to recommend the adoption of the Merger Agreement by holders of Denbury common stock and that the adoption of the Merger Agreement be submitted to a vote at a meeting of holders of Denbury common stock.

Accordingly, the Denbury board of directors unanimously recommends that holders of Denbury common stock vote “FOR” the adoption of the Merger Agreement and “FOR” the approval on an advisory (non-binding) basis of certain compensation that may be paid or become payable to Denbury’s named executive officers in connection with the Merger.

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

A: Denbury’s directors and executive officers have the right to vote approximately      shares of the then-outstanding Denbury common stock at the Special Meeting, collectively representing approximately    % of the Denbury common stock outstanding and entitled to vote on that date. We currently expect that Denbury’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 Denbury 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 stockholder 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 in connection with the Merger, ExxonMobil will be issuing additional shares of ExxonMobil common stock to Denbury stockholders in exchange for their shares of Denbury common stock, 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 Denbury 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 Denbury intend to report the Merger consistent with such qualification. Each of ExxonMobil and Denbury has agreed in the Merger Agreement to use its reasonable 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 permit or cause any of its respective subsidiaries or affiliates to, take or cause to be taken any action reasonably likely to cause the Merger to fail to qualify as a “reorganization” within the meaning of Section 368(a) of the Code for U.S. federal income tax purposes. As of the date of this proxy statement/prospectus, Davis Polk & Wardwell LLP (“Davis Polk”), legal counsel to ExxonMobil, and Vinson & Elkins, L.L.P. (“Vinson & Elkins”), legal counsel to Denbury, are of the opinion that the Merger will qualify as a “reorganization” within the meaning of Section 368(a) of the Code and have provided opinions to ExxonMobil and Denbury, respectively, to that effect. These opinions of counsel are based on customary assumptions and representations, covenants and undertakings of ExxonMobil, Denbury and Merger Sub, all as of the date hereof. If any of the assumptions, representations, covenants or undertakings is incorrect, incomplete, inaccurate, or is violated, the validity of the opinions may be affected and the U.S. federal income tax consequences of the Merger could differ materially from those described in this proxy statement/prospectus. The receipt of an opinion from counsel on the qualification of the Merger as a “reorganization” within the meaning of Section 368(a) of the Code is not a condition to either party’s obligation to complete the merger.Merger. ExxonMobil and Denbury have not sought, and will not seek, any ruling from the U.S. Internal Revenue Service (the “IRS”) regarding any matters related to the transactions, and, as a result, there can be no assurance that the IRS will agree with the opinions or would not assert, or that a court would not sustain, a position contrary to the treatment 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

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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 received in lieu 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 value of the ExxonMobil common stock it receives in the Merger plus the amount of any cash it receives in lieu of fractional shares of ExxonMobil common stock and (ii) such holder’s adjusted tax basis in its shares of Denbury common stock exchanged in the Merger.

The U.S. federal income tax consequences described above may not apply to all holders of Denbury common stock. You should read “U.S. Federal Income Tax Consequences of the Merger” beginning on page 137 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 own tax advisor to determine the tax consequences of the Merger to you.

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

A: ExxonMobil and Denbury currently expect to complete the Merger in the fourth quarter of 2023, subject to timing of satisfaction of closing conditions to the Merger. However, neither ExxonMobil nor Denbury 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 31, 107 and 116, respectively, of this proxy statement/prospectus.

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

A: Yes. ExxonMobil, Merger Sub and Denbury 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 approval and adoption of the Merger Agreement by holders of a majority of Denbury 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 and Merger Sub’s obligation to complete the Merger, without the imposition of a Burdensome Condition (see “The Merger Agreement – Reasonable Best Efforts Covenant” beginning on page 128 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 117 and 107, 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 Denbury’s stockholders at the Special Meeting or the Merger is not completed for any other reason, Denbury’s stockholders will not receive any consideration for shares of Denbury stock they own. Instead, Denbury will remain an independent public company, Denbury 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 Denbury will continue to file periodic reports with the Securities and Exchange Commission (the “SEC”) on account of Denbury’s common stock. If the Merger is not completed for any reason, including as a result of Denbury stockholders failing to approve the necessary proposals, the ongoing businesses of Denbury 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 Denbury” beginning on page 37 of this proxy statement/prospectus.

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Under specified circumstances, Denbury and/or ExxonMobil 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 133 of this proxy statement/prospectus.

Q: When and where is the Special Meeting?

A: The Special Meeting will be held virtually at www.virtualshareholdermeeting.com/DEN2023SM on   , 2023, at   , Central Time. On or about   , 2023, Denbury commenced mailing this proxy statement/prospectus and the enclosed form of proxy to its stockholders entitled to vote at the Special Meeting.

The Special Meeting can be accessed by visiting www.virtualshareholdermeeting.com/DEN2023SM , where Denbury stockholders will be able to participate and vote online. Denbury encourages its stockholders to access the meeting prior to the start time leaving ample time for check-in. Please follow the instructions as outlined in this proxy statement/prospectus. This proxy statement/prospectus is first being furnished to Denbury’s stockholders on or about     , 2023.

Denbury has chosen to hold the Special Meeting solely via live webcast and not in a physical location. Denbury has adopted a virtual format for the Special Meeting to make participation accessible for stockholders from any geographic location with Internet connectivity.

Q: Who can vote at the Special Meeting?

A: All holders of shares of Denbury common stock who hold such shares of record at the close of business on September 27, 2023, the record date for the Special Meeting, are entitled to receive notice of, and to vote at, the Special Meeting.

Q: How many votes may I cast?

A: Each outstanding share of Denbury common stock entitles its holder of record to one vote on each matter considered at the Special Meeting. Only Denbury stockholders who held shares of common stock of Denbury of record at the close of business on are entitled to vote at the Special Meeting and any adjournment or postponement of the Special Meeting.

Q: What is the record date in connection with the Special Meeting?

A: The record date for the determination of holders of Denbury common stock entitled to notice of and to vote at the Special Meeting is September 27, 2023.

Q: What constitutes a quorum at the Special Meeting?

A: A quorum is necessary to conduct business at the Special Meeting. A quorum requires the presence at the Special Meeting, by attending the Special Meeting or being represented by proxy, of one-third of the outstanding shares of Denbury common stock entitled to vote on each matter considered at the Special Meeting.

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 complete, sign, date and return the enclosed proxy card in the postage-prepaid envelope provided as soon as possible so that your shares will be represented and voted at the Special Meeting.

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Additional information on voting procedures can be found under “The Special Meeting” beginning on page 44 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, your proxy will be voted in accordance with your instructions.

Additional information on voting procedures can be found under “The Special Meeting” beginning on page 44 of this proxy statement/prospectus.

Q: Who will count the votes?

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

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

A: If you are a stockholder of record of Denbury common stock at the close of business on September 27, 2023, you may vote your shares in any one of the following ways:

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

If you submitare a proxy by telephonebeneficial holder of Denbury 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 Denbury 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

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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 may submit questions during the Special Meeting. As part of the Special Meeting, we will hold a live question and answer session during which we intend to answer questions submitted during the next questionmeeting in accordance with the Special Meeting procedures which are pertinent to Denbury and the meeting matters, as time permits. Questions may be submitted during the Special Meeting through www.virtualshareholdermeeting.com/DEN2023SM. Questions and answers will be grouped by topic and substantially similar questions will be grouped and answered once.

Q: What if I need technical assistance?

A: We encourage you to access the Special Meeting before it begins. Online check-in will start shortly before the meeting on   , 2023   at Central Time. If you encounter any difficulties accessing the meeting during the check-in or meeting time, please call (800) 586-1548 (toll free) or (303) 562-9288 (international).

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 Denbury 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 Denbury 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.

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 Denbury common stock are registered directly in your name with Denbury’s transfer agent, Broadridge Corporate Issuer Solutions, Inc., 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 Denbury.

If your shares of Denbury common stock are held through a bank, broker or other nominee, you are considered the beneficial owner of shares of Denbury 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

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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 Denbury 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?

A quorum is necessary to conduct business at the Special Meeting. A quorum requires the presence at the Special Meeting of one-third of the outstanding shares of Denbury common stock entitled to vote on each matter considered at the Special Meeting, via the Special Meeting website or represented by proxy. 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 Special Meeting” beginning on page 44 of this proxy statement/prospectus.

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

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

Beneficial owners of Denbury common stock may change their voting instruction by submitting new voting instructions to the brokers, banks or other nominees that hold their shares of record or by following the instructions for voting set forth on the voting instruction form with a 16-digit control number provided by their brokers, banks or other nominees and voting at the Special Meeting.

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Additional information can be found under “The Special Meeting” beginning on page 44 of this proxy statement/prospectus.

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

A: The record date for holders of Denbury common stock entitled to vote at the Special Meeting is September 27, 2023, which is earlier than the date of the Special Meeting. If you holdsell or otherwise transfer your shares throughafter the record date but before the Special Meeting, unless special arrangements (such as provision of a brokerproxy) are made between you and the person to whom you transfer your shares and each of you notifies Denbury in writing of such special arrangements, you will retain your right to vote such shares at the Special Meeting but will otherwise transfer ownership of your shares of Denbury common stock.

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

A: Only holders of shares of Denbury common stock at the effective time will become entitled to receive the Merger Consideration. If you must followsell your shares of Denbury common stock prior to the directionscompletion 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 Denbury have interests in the Merger that may differ from your broker or other nomineebe in orderaddition to revokemy interests as a Denbury stockholder?

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

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

The Denbury board of directors 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 Denbury’s Directors and Executive Officers in the Merger” beginning on page 140 of this proxy statement/prospectus.

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

A: Denbury 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 Denbury and ExxonMobil file with the SEC are publicly available when filed. See “Where You Can Find More Information” beginning on page 178 of this proxy statement/prospectus.

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

A: Denbury 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 109 of this proxy statement/prospectus.

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

A: You can find more information about ExxonMobil and Denbury from various sources described in “Where You Can Find More Information” beginning on page 178 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 Denbury or Denbury’s proxy solicitor:

attending the special meeting and voting by ballot in person.

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