Regeneron Pharmaceuticals, Inc. (REGN) Faces Securities Class Action Amid Disclosures About Key Trial’s Protocol and Ultimate Failure - HBSS

Regeneron Pharmaceuticals faces a securities class action lawsuit after failing to disclose critical information about its Phase 3 clinical trial for a melanoma treatment combination. The company allegedly made misleading statements about the trial's progress while concealing that preliminary statistical assumptions were flawed and the primary endpoint was unlikely to be achieved. The trial ultimately failed to reach statistical significance on May 15, 2026, resulting in an $11 billion market cap loss. The lawsuit covers investors who purchased shares between August 1, 2025 and May 15, 2026.