Regeneron Pharmaceuticals, Inc. Investors with Substantial Losses Have Opportunity to Lead Regeneron Class Action Lawsuit – Hagens Berman

A securities class action lawsuit has been filed against Regeneron Pharmaceuticals after its Phase 3 clinical trial for a melanoma therapy failed to reach statistical significance. The lawsuit alleges the company made false and misleading statements about the trial's progress while concealing that preliminary statistical assumptions were flawed and the treatment arm was not achieving meaningful differentiation. The stock plunged following the May 15, 2026 announcement, resulting in an $11 billion market cap loss. The class period covers August 1, 2025 to May 15, 2026.