The lawsuit targets statements tied to the Phase III Fianlimab-Libtayo study after REGN fell 13.95% from its class-period high following a protocol amendment and later trial results.
A securities class action has been filed against Regeneron Pharmaceuticals, Inc. on behalf of investors who bought shares between August 1, 2025 and May 15, 2026, with lead plaintiff applications due by September 14, 2026. The complaint alleges Regeneron and certain executives downplayed a prolonged slowdown in progression-free survival event accrual in the Phase III Fianlimab-Libtayo study, an issue that later became central to investor concerns about trial execution and statistical significance. REGN fell 6.2% on April 29, 2026, dropping from $731.77 to $686.36 after the company said the primary analysis of progression-free survival would include all enrolled patients with at least 6 months of follow-up. The stock then fell 9.8% on May 18, 2026, from $698.25 to $629.68. From the class period high, the shares lost $102.09, or 13.95%. The release says analysts viewed the protocol amendment as a meaningful shift in the study's risk profile, with Wells Fargo cutting its price target by 3% and Evercore ISI saying an amendment appeared necessary to support the timing of the readout. The filing also cites a later company announcement that the trial did not reach statistical significance for the primary endpoint of improvement in progression-free survival. Levi & Korsinsky, LLP said investors who bought during the class period and suffered losses may seek compensation, while investors do not need to apply by the deadline unless they want to serve as lead plaintiff.