Gossamer Bio, Inc
Securities Class Action
Company Name: Gossamer Bio, Inc (GOSS)
Download ComplaintJune 16, 2025 - February 20, 2026
June 1, 2026|34 days left
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Allegations
On February 23, 2026, Gossamer issued a press release and hosted a call to announce topline results for its Phase 3 PROSERA study evaluating seralutinib for the treatment of pulmonary arterial hypertension, which failed to meet the primary endpoint of improved six-minute walk distance at Week 24, with a +13.3 meter placebo-adjusted gain (p-0.0320) failing to meet the required 0.025 alpha threshold. Gossamer attributed this miss to patients at Latin American sites performing particularly well on placebo due to enrollment of a heavily treated lower-risk population. On this news, Gossamer’s stock price fell $1.71 per share, or 80.13%, to close at $0.42 per share on February 23, 2026.
Lead Plaintiff
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