Philadelphia, Pennsylvania--(Newsfile Corp. - April 9, 2026) - National plaintiffs' law firm Berger Montague PC announces a class action lawsuit against Gossamer Bio, Inc. (NASDAQ: GOSS) ("Gossamer" or the "Company") on behalf of investors who purchased or acquired Gossamer shares during the period from June 16, 2025 through February 20, 2026 (the "Class Period").

Investor Deadline: Investors who purchased or acquired Gossamer securities during the Class Period may, no later than June 1, 2026, seek to be appointed as a lead plaintiff representative of the class. To learn your rights, CLICK HERE.

According to the complaint, clinical-stage biopharmaceutical company Gossamer made materially false and misleading statements regarding the design and anticipated outcomes of its Phase 3 PROSERA study evaluating seralutinib for the treatment of pulmonary arterial hypertension (PAH).

The suit alleges that investors began to learn the truth on February 23, 2026, when Gossamer announced that its Phase 3 PROSERA study failed to meet the primary endpoint of improved six-minute walk distance (6MWD) at Week 24. The Company attributed the results to unexpectedly strong placebo performance at Latin American sites. On this news, Gossamer's stock price fell from $2.13 to $0.42 per share, a decline of over 80% in a single trading day.

If you are a Gossamer investor and would like to learn more about this action, CLICK HERE or please contact Berger Montague: Andrew Abramowitz at aabramowitz@bergermontague.com or (215) 875-3015, or Caitlin Adorni at cadorni@bergermontague.com or (267)764-4865.

About Berger Montague
Berger Montague is one of the nation's preeminent law firms focusing on complex civil litigation, class actions, and mass torts in federal and state courts throughout the United States. With more than $2.4 billion in 2025 post-trial judgments alone, the Firm is a leader in the fields of complex litigation, antitrust, consumer protection, defective products, environmental law, employment law, securities, and whistleblower cases, among many other practice areas. For over 55 years, Berger Montague has played leading roles in precedent-setting cases and has recovered over $50 billion for its clients and the classes they have represented. Berger Montague is headquartered in Philadelphia and has offices in Chicago; Malvern, PA; Minneapolis; San Diego; San Francisco; Toronto, Canada; Washington, D.C., and Wilmington, DE.

To view the source version of this press release, please visit https://www.newsfilecorp.com/release/291738

Source: Berger Montague