DEFA14A

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 (Amendment No. )

Filed by the Registrant ☒

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

☒ Definitive Additional Materials

☐ Soliciting Material Pursuant to §240.14a-12

MONTE ROSA THERAPEUTICS, INC.

(Name of Registrant as Specified In Its Charter)

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

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☒	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

Monte Rosa Therapeutics PROXY TABULATOR: P.O. BOX 8016, CARY, NC 27512-9903 Your vote matters! Monte Rosa Therapeutics, Inc. Annual Meeting of Stockholders Thursday, June 11, 2026 8:30 AM, Eastern Time Annual Meeting to be held live via the Internet - please visit www.proxydocs.com/GLUE for more details. You must register to attend the meeting online and/or participate at www.proxydocs.com/GLUE prior to the deadline of June 9, 2026 at 5:00 PM ET. For a convenient way to view proxy materials, VOTE, and obtain directions to attend the meeting go to www.proxydocs.com/GLUE To vote your proxy while visiting this site, you will need the 12 digit control number in the box below. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. This is not a ballot. You cannot use this notice to vote your shares. We encourage you to access and review all of the important information contained in the proxy materials before voting. Under United States Securities and Exchange Commission rules, proxy materials do not have to be delivered in paper. Proxy materials can be distributed by making them available on the Internet. If you want to receive a paper or e-mail copy of the proxy material, you must request one. There is no charge to you for requesting a copy. In order to receive a paper package in time for this year's meeting, you must make this request on or before June 1, 2026. SEE REVERSE FOR FULL AGENDA Meeting Materials: Notice of Meeting and Proxy Statement & Annual Report on Form 10-K Important Notice Regarding the Availability of Proxy Materials for the Stockholders Meeting to be Held on June 11, 2026 For Stockholders of Record as of April 16, 2026 To order paper materials, use one of the following methods. Internet: www.investorelections.com/GLUE Call: 1-866-648-8133 Email: paper@investorelections.com * If requesting material by e-mail, please send a blank e-mail with the 12 digit control number (located below) in the subject line. No other requests, instructions OR other inquiries should be included with your e-mail requesting material. Your control number Have the 12 digit control number located in the box above available when you access the website and follow the instructions. Copyright © 2026 BetaNXT, Inc. or its affiliates. All Rights Reserved

Monte Rosa Therapeutics Monte Rosa Therapeutics, Inc. Annual Meeting of Stockholders FOR THE DIRECTOR NOMINEES LISTED IN PROPOSAL 1 AND FOR PROPOSAL 2 PROPOSAL 1. To elect three Class II director nominees to our board of directors, to serve until the Company's 2029 annual meeting of stockholders and until their successor has been duly elected and qualified, or until their earlier death, resignation or removal; 1.01 Andrew Schiff, M.D. 1.02 Chandra P. Leo, M.D. 1.03 Anthony Manning, Ph.D. 2. To ratify the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2026; and 3. To transact any other business properly brought before the Annual Meeting or any adjournment or postponement of the Annual Meeting.

SEC Form DEFA14A filed by Monte Rosa Therapeutics Inc.