UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.     )

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 Rule 14a-12

JOHN MARSHALL BANCORP, INC.

(Name of Registrant as Specified in Its Charter)

N/A

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check the appropriate box):

x No 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.

1.Election of Directors: Philip Allin Christopher Bergstrom Philip Chase Jean Edelman Michael Foster Michael Garcia Subhash Garg Ronald Gordon Jonathan Kinney O. Leland Mahan Lim Nguonly 2. To ratify the appointment of Yount, Hyde & Barbour, P.C. as the Company’s independent registered public accounting firm for fiscal year ended December 31, 2022. THE BOARD OF DIRECTORS RECOMMENDS A VOTE "FOR" THE ELECTION OF DIRECTORS AND "FOR" PROPOSAL 2. NOMINEES: This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. If you want to receive a paper or e-mail copy of the proxy materials you must request one. There is no charge to you for requesting a copy. To facilitate timely delivery please make the request as instructed below before 6/8/2022. Please visit http://www.astproxyportal.com/ast/26437, where the following materials are available for view: • Notice of Annual Meeting of Shareholders • Proxy Statement • Form of Electronic Proxy Card • Registration Statement on Form 10 TO REQUEST MATERIAL: TELEPHONE: 888-Proxy-NA (888-776-9962) 718-921-8562 (for international callers) E-MAIL: info@astfinancial.com WEBSITE: https://us.astfinancial.com/OnlineProxyVoting/ProxyVoting/RequestMaterials TO VOTE:ONLINE: To access your online proxy card, please visit www.voteproxy.com and follow the on-screen instructions or scan the QR code with your smartphone . You may enter your voting instructions at www.voteproxy.com up until 11:59 PM Eastern Time the day before the cut-off or meeting date. IN PERSON: You may vote your shares in person by attending the Annual Meeting. TELEPHONE: To vote by telephone, please visit www.voteproxy.com to view the materials and to obtain the toll free number to call. MAIL: You may request a card by following the instructions above. COMPANY NUMBER ACCOUNT NUMBER CONTROL NUMBER JOHN SMITH 1234 MAIN STREET APT. 203 NEW YORK, NY 10038 Please note that you cannot use this notice to vote by mail. Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting of JOHN MARSHALL BANCORP, INC. To Be Held On: June 22, 2022 at 10:00 a.m.