Company: SION
Filing Date: 2025-04-29
Form Type: DEF 14A
Source: 0001193125-25-101830
Chunk: 64

Company: Sionna Therapeutics, Inc.
Filing Date: 2025-04-29
Form: DEF 14A
Chunk 64
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 preceding year’s annual meeting, a stockholder’s notice must be so received no earlier than the 120th day prior to such annual meeting and not later than the close of business on the later of (A) the 90th day prior to such annual meeting and (B) the tenth day following the day on which notice of the date of such annual meeting was mailed or public disclosure of the date of such annual meeting was made, whichever first occurs. For stockholder proposals to be brought before the 2026 annual meeting of stockholders, the required notice must be received by our corporate secretary at our principal executive offices no earlier than February 12, 2026 and no later than March 14, 2026. Stockholder proposals and the required notice should be addressed to Sionna Therapeutics, Inc., 21 Hickory Drive, Suite 500, Waltham, MA 02451, Attention: Chief Legal Officer.

To comply with the SEC’s universal proxy rules, stockholders who intend to solicit proxies in support of director nominees other than our nominees must provide notice by the same deadline noted herein to submit a notice of nomination for the 2025 annual meeting of stockholders. Such notice must comply with the additional requirements of Rule 14a-19(b).

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### OTHER MATTERS
Our board of directors does not know of any other matters to be brought before the Annual Meeting. If any other matters not mentioned in this proxy statement are properly brought before the meeting, the individuals named in the enclosed proxy intend to use their discretionary voting authority under the proxy to vote the proxy in accordance with their best judgment on those matters.

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SCAN TO VIEW MATERIALS & VOTE w SIONNA THERAPEUTICS, INC. VOTE BY INTERNET 21 HICKORY DRIVE, SUITE 500 Before The Meeting—Go to www.proxyvote.com or scan the QR Barcode above WALTHAM, MA 02451 Use the Internet to transmit your voting instructions and for electronic delivery of information up until 11:59 p.m. Eastern Time on June 11, 2025. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. During The Meeting—Go to www.virtualshareholdermeeting.com/SION2025 You may attend the meeting via the Internet and vote during the meeting. Have the information that is printed in the box