144 0001780117 XXXXXXXX LIVE 0002036042 Sionna Therapeutics, Inc. 001-42504 21 HICKORY DRIVE, SUITE 500 WALTHAM MA 02451 617-819-2020 RA Capital Nexus Fund, L.P. Director 10% Stockholder Common BTIG, LLC

350 Bush Street 9th Floor San Francisco CA 94104

9924 433281.84 44628788 11/21/2025 NASDAQ GM Common 09/18/2020 Private Transaction Sionna Therapeutics N 9924 09/18/2020 Wire N RA Capital Nexus Fund, L.P.

200 BERKELEY STREET BOSTON MA 02116

Common 10/24/2025 122271 4829704.50 RA Capital Nexus Fund, L.P

200 BERKELEY STREET BOSTON MA 02116

Common 10/28/2025 31392 1242555.00 RA Capital Nexus Fund, L.P

200 BERKELEY STREET 18TH FLOOR BOSTON MA 02116

Common 11/17/2025 32310 1311488.75 RA Capital Nexus Fund, L.P

200 BERKELEY STREET, 18TH FLOOR BOSTON MA 02116

Common 11/18/2025 2728 107945.60 RA Capital Nexus Fund, L.P

200 BERKELEY STREET 18TH FLOOR BOSTON MA 02116

Common 11/19/2025 18696 748122.31 RA Capital Nexus Fund, L.P

200 BERKELEY STREET 18TH FLOOR BOSTON MA 02116

Common 11/20/2025 2023 81182.38 11/21/2025 Rajeev Shah