Atlas Venture Opportunity Fund II, L.P. Sells Sionna Therapeutics Common Stock

Atlas Venture Opportunity Fund II, L.P. has filed a Form 144 with the SEC, indicating its intention to sell 15,418 shares of Sionna Therapeutics, Inc. common stock. The shares were acquired through a private placement on March 4, 2024. The filing also details numerous sales of Sionna Therapeutics common stock by Atlas Venture Opportunity Fund II, L.P. and Atlas Venture Fund XI, LP over the past three months, totaling millions of dollars in gross proceeds. The sales were executed through Merrill Lynch on the NASDAQ exchange. The notice was signed by Ommer Chohan on October 21, 2025.