Regeneron Pharmaceuticals IncClass action lawsuit filed over failed trial and alleged misleading statements.

A securities class action lawsuit has been filed against Regeneron Pharmaceuticals after the company disclosed that a Phase 3 trial of its Fianlimab and Libtayo combination for melanoma failed to meet its primary endpoint, triggering an $11 billion market cap wipeout. The suit, brought by Hagens Berman, seeks to represent investors who purchased Regeneron shares between August 1, 2025 and May 15, 2026, and alleges the company made false and misleading statements about the trial's prospects while concealing flawed statistical assumptions and a low likelihood of success. Regeneron revealed on April 29, 2026 that it had altered the trial protocol, and on May 15, 2026 reported the study did not achieve statistical significance for progression-free survival. The lead plaintiff deadline is September 14, 2026.
Regeneron Pharmaceuticals IncClass action lawsuit filed over failed trial and alleged misleading statements.