SION INVESTIGATION ALERT: Investigation Launched into Sionna Therapeutics, Inc., RGRD Law Attorneys Encourage Investors and Potential Witnesses to Contact Law Firm

Robbins Geller Rudman & Dowd LLP is investigating potential violations of United States federal securities laws involving Sionna Therapeutics, Inc. (NASDAQ: SION). If you have information that could assist in the Sionna Therapeutics investigation or if you are a Sionna Therapeutics investor who suffered a loss and would like to learn more, you can provide your information here: https://www.rgrdlaw.com/cases-sionna-therapeutics-inc-investigation-sion.html You can also contact attorneys Ken Dolitsky or Michael Albert of Robbins Geller by calling 800/851-7783 or via e-mail at [email protected] .

Sionna Therapeutics is a clinical-stage biopharmaceutical company that researches and develops medicines for the treatment of cystic fibrosis.

On August 10, 2026, Sionna Therapeutics announced that its "SION-719 Phase 2a proof-of-concept trial did not achieve key activity endpoint of sweat chloride reduction when added to standard of care." On this news, the price of Sionna Therapeutics stock fell more than 91%.

Robbins Geller Rudman & Dowd LLP is one of the world's leading law firms representing investors in securities fraud and shareholder rights litigation. Our Firm ranked #1 on the most recent ISS Securities Class Action Services Top 50 Report, recovering more than $916 million for investors in 2025. This marks our fourth #1 ranking in the past five years. And in those five years alone, Robbins Geller recovered $8.4 billion for investors — $3.4 billion more than any other law firm. With 200 lawyers in 10 offices, Robbins Geller is one of the largest plaintiffs' firms in the world, and the Firm's attorneys have obtained many of the largest securities class action recoveries in history, including the largest ever — $7.2 billion — in In re Enron Corp. Sec. Litig. Attorney advertising. Past results do not guarantee future outcomes. Services may be performed by attorneys in any of our offices.