UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities

Exchange Act of 1934

Filed by the Registrant x        Filed by a party other than the Registrant ¨

Check the appropriate box:

¨    Preliminary Proxy Statement

¨    Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

¨    Definitive Proxy Statement

x    Definitive Additional Materials

¨    Soliciting Material Pursuant to §240.14a-12

Marathon Petroleum Corporation

(Name of Registrant as Specified In Its Charter)

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

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xNo fee required.

¨Fee paid previously with preliminary materials.

¨Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

	YOUR VOTE IS VERY IMPORTANT! PLEASE VOTE TODAY	April 4, 2023

DEAR SHAREHOLDER,

We are contacting you to stress the importance of voting your shares in connection with Marathon Petroleum Corporation’s 2023 Annual Meeting of Shareholders, to be held on April 26, 2023. According to our latest records, we have not yet received your vote for this meeting, and we would like to remind you to vote your shares. Your vote is very important!

Shareholders are being asked to vote on the following important proposals to enhance MPC's governance:

	Proposal		Benefits to MPC Shareholders
ü	Proposal 4.	Declassify the Board of Directors	Declassifying the Board will allow shareholders to vote on all director candidates each year, rather than electing one third of the Board every year.
ü	Proposal 5.	Eliminate the Supermajority Provisions	Eliminating the supermajority requirements in MPC's Restated Certificate of Incorporation will enhance our governance practices.
ü			Increasing the maximum size of the Board, from 12 to 15 directors, will provide our Board with near-term opportunity to add additional talent to the Board.
	Proposal 6.	Increase the Maximum Size of the Board of Directors

Your vote is extremely important no matter how many shares you hold. MPC’s Restated Certificate of Incorporation requires the affirmative vote of at least 80% of the outstanding shares of our common stock to approve these proposals. Your Board of Directors unanimously recommends that shareholders vote FOR each of these proposals.

If you have any questions or need assistance with voting, please contact our proxy solicitor, D.F. King & Co., toll-free at (866) 864-7964. For more information on the Annual Meeting, see MPC's 2023 Proxy Statement, available on our website at www.marathonpetroleum.com by selecting "Investors" and then "Annual Report & Proxy Statement."

On behalf of the Board of Directors, thank you for your continued support of Marathon Petroleum Corporation.

Sincerely,

John P. Surma

Independent Chairman of the Board

þ	Your vote is important. Even if you plan to attend the virtual Annual Meeting, please vote as soon as possible using one of the following options:
Via the Internet:		Call Toll-Free:	Mail Signed Proxy Card:
Follow the instructions in the Notice, proxy card or voting instruction form.		Call the toll-free number on your proxy card or voting instruction form.	Follow the instructions on your proxy card or voting instruction form.