X0609 4 2026-06-17 0 0002036042 Sionna Therapeutics, Inc. SION 0001690959 Resnick Joshua false C/O SIONNA THERAPEUTICS, INC. 21 HICKORY DRIVE, SUITE 500 WALTHAM MA 02451 1 0 0 0 0 Non-Qualified Stock Option (right to buy) 36.73 2026-06-17 4 A 0 17340 0.0 A 2036-06-16 Common Stock 17340 17340 D Under the Reporting Person's arrangement with RA Capital Management, L.P. (the "Adviser"), the Reporting Person holds the option for the benefit of the RA Capital Healthcare Fund, L.P. (the "Fund"), the RA Capital Nexus Fund, L.P. (the "Nexus Fund"), the RA Capital Nexus Fund III, L.P. (the "Nexus Fund III"), and a separately managed account (the "Account"). The Reporting Person is obligated to turn over to the Adviser any net cash or stock received upon exercise of the stock option, which will offset advisory fees owed by the Fund, the Nexus Fund, the Nexus Fund III and the Account to the Adviser. The Reporting Person therefore disclaims beneficial ownership of the stock option and underlying Common Stock. This option vests in full upon the earlier of June 17, 2027 or the date of the next annual meeting of Sionna Therapeutics, Inc., subject to the Reporting Person's continued service on such vesting date. By: Jennifer Fitzpatrick, Attorney-in-Fact For: Joshua Resnick 2026-06-18