Company: SION
Filing Date: 2025-04-29
Form Type: DEF 14A
Source: 0001193125-25-101830
Chunk: 65

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-04-29
Form: DEF 14A
Chunk 65
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 marked by the arrow available and follow the instructions. VOTE BY PHONE—1-800-690-6903Use any touch-tone telephone to transmit your voting instructions up until 11:59 p.m. Eastern Time on June 11, 2025. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717. TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: V72399-P31556 KEEP THIS PORTION FOR YOUR RECORDS THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. DETACH AND RETURN THIS PORTION ONLY SIONNA THERAPEUTICS, INC. For All With hold All Except For All To withhold authority to vote for any individual nominee(s), mark “For All Except” and write the The Board of Directors recommends you vote FOR number(s) of the nominee(s) on the line below. the following: 1. To elect three class I directors to serve until our 2028 ! ! ! annual meeting of stockholders and until his or her successor has been duly elected and qualified, or until his or her earlier death, resignation or removal. Nominees: 01) Joshua Resnick, M.D., M.B.A. 02) Bruce Booth, D.Phil. 03) Lucian Iancovici, M.D. The Board of Directors recommends you vote FOR the following proposal: For Against Abstain 2. To ratify the appointment of Deloitte & Touche LLP as our independent registered public accounting firm for the fiscal year ending ! ! ! December 31, 2025. NOTE: In their discretion, the proxies are authorized to vote upon such other business as may properly come before the meeting or any continuation, adjournment or postponement thereof. Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name by authorized officer. Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date

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