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 10,604 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 dated October 17, 2025, with the plan adoption date being February 25, 2025. The aggregate market value of the shares to be sold is approximately $346,856.84. Additionally, the filing discloses that Atlas Venture Opportunity Fund II, L.P. has sold a significant number of shares in the past three months, totaling over $8.5 million in gross proceeds. The shares are traded on NASDAQ, and the transactions were facilitated by Merrill Lynch.