Atlas Venture Fund XI, LP's Sale of Sionna Therapeutics Common Stock

Atlas Venture Fund XI, LP has filed a Form 144 notice indicating its intention to sell 73,460 shares of Sionna Therapeutics, Inc. common stock. The shares were acquired through a private placement on March 4, 2024. The notice, signed by Ommer Chohan, was filed on October 21, 2025, with a plan adoption date of February 25, 2025. The aggregate market value of the shares to be sold is approximately $2,365,412. Additionally, the filing discloses recent sales of Sionna Therapeutics common stock by Atlas Venture Fund XI, LP and Atlas Venture Opportunity Fund II, L.P. over the past three months, totaling significant amounts. The sales were executed through Merrill Lynch, with proceeds ranging from $1,048.25 to $4,526,479.35.