Gossamer Bio, Inc. Investigated by the Portnoy Law Firm

LOS ANGELES, March 18, 2026 (GLOBE NEWSWIRE) -- The Portnoy Law Firm advises Gossamer Bio, Inc. (“Gossamer" or the "Company") (NASDAQ:GOSS) investors that the firm has initiated an investigation into possible securities fraud, and may file a class action on behalf of investors.

Investors are encouraged to contact attorney Lesley F. Portnoy, by phone 310-692-8883 or email: lesley@portnoylaw.com, to discuss their legal rights, or join the case via http://portnoylaw.com/gossamer-bio-inc. The Portnoy Law Firm can provide a complimentary case evaluation and discuss investors’ options for pursuing claims to recover their losses.

Gossamer’s stock price plummeted $1.71 per share, or 80.14%, to close at $0.423 per share on February 23, 2026, thereby injuring investors. This massive valuation collapse was triggered by a February 23, 2026, announcement regarding the results of the Phase 3 PROSERA trial. The study was designed to evaluate the efficacy of seralutinib in patients suffering from pulmonary arterial hypertension, a critical component of the Company's clinical pipeline.

The market reacted with extreme volatility following the revelation that the PROSERA trial failed to meet its primary endpoint. The inability of seralutinib to achieve its main clinical objective led to an immediate and severe erosion of shareholder value, as investors processed the implications for the drug's regulatory approval and future commercial viability. The sudden loss of confidence in the Company's lead therapeutic candidate resulted in a rapid contraction of market capitalization, leaving the future of the Gossamer clinical program in significant doubt.

The Portnoy Law Firm represents investors in pursuing claims caused by corporate wrongdoing. The Firm’s founding partner has recovered over $5.5 billion for aggrieved investors. Attorney advertising. Prior results do not guarantee similar outcomes.

Lesley F. Portnoy, Esq.
Admitted CA, NY and TX Bar
lesley@portnoylaw.com
310-692-8883
www.portnoylaw.com

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