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Regeneron investors sue over 2025-2026 disclosures as stock fell after trial updates

Regeneron investors sue over 2025-2026 disclosures as stock fell after trial updates

The proposed class action targets buyers between Aug. 1, 2025, and May 15, 2026, citing declines of about 6.2% and 9.8% after disclosures tied to the Phase III Fianlimab-Libtayo study.

Fact Check
Three separate law firm alerts (Levi & Korsinsky, Faruqi & Faruqi, Gainey McKenna & Egleston) consistently confirm a proposed securities class action against Regeneron targeting purchasers between Aug 1, 2025 and May 15, 2026, with the named case Cheatham v. Regeneron (No. 7:26-cv-06026, S.D.N.Y.) and a Sep 14, 2026 lead plaintiff deadline. They report a ~6.2% decline (Apr 29, 2026) and a ~9.8% decline (following the May 15, 2026 disclosure), matching the claim exactly. Regeneron's own investor release confirms the underlying event: the May 15, 2026 announcement that the Phase 3 Fianlimab-Libtayo trial missed its primary progression-free survival endpoint. Independent press (Endpoints, WSJ, FierceBiotech) corroborate the trial failure and stock drop. All elements of the claim are substantiated.
Summary

A securities class action has been filed against Regeneron Pharmaceuticals, Inc. in the United States District Court for the Southern District of New York on behalf of investors who bought the company’s common stock between August 1, 2025, and May 15, 2026. Levi & Korsinsky, LLP said the case, Allen Cheatham v. Regeneron Pharmaceuticals, Inc., et al. (Case No. 7:26-cv-06026), alleges Regeneron made materially false and misleading statements, or concealed adverse facts, about the Phase III Fianlimab-Libtayo study. The complaint says the trial’s preliminary statistical assumptions were flawed, the active treatment arm was not achieving meaningful clinical differentiation over standard therapies, and the study would ultimately fail to reach statistical significance on its primary endpoint. The filing points to two stock drops: from $731.77 on April 28, 2026 to $686.36 on April 29, 2026 after Regeneron disclosed changes to the study’s progression-free survival analysis, and from $698.25 on May 15, 2026 to $629.68 on May 18, 2026 after the company said the Phase 3 trial did not reach statistical significance for improvement in progression-free survival (time patients live without disease worsening). Investors seeking appointment as lead plaintiff have until September 14, 2026.

Terms & Concepts
  • progression-free survival: Time patients live without disease worsening.
  • statistical significance: A result unlikely due to chance alone.
  • lead plaintiff: Investor appointed to represent a class.