Regeneron Pharmaceuticals, Inc. Class Action Lawsuit - REGN
Case Summary
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The Regeneron class action lawsuit seeks to represent purchasers or acquirers of Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) common stock between August 1, 2025 and May 15, 2026, inclusive (the “Class Period”). Captioned Cheatham v. Regeneron Pharmaceuticals, Inc., No. 26-cv-06026 (S.D.N.Y.), the Regeneron class action lawsuit charges Regeneron and certain of Regeneron’s top executives with violations of the Securities Exchange Act of 1934.
If you suffered substantial losses and wish to serve as lead plaintiff of the Regeneron class action lawsuit, please provide your information in the form on this page. You can also contact attorneys Ken Dolitsky or Michael Albert of Robbins Geller by calling 800/851-7783 or via e-mail at info@rgrdlaw.com. Lead plaintiff motions for the Regeneron class action lawsuit must be filed with the court no later than September 14, 2026.
CASE ALLEGATIONS: Regeneron is a pharmaceutical company that discovers, invents, develops, manufactures, tests, and commercializes medicines to treat various disorders worldwide.
The Regeneron class action lawsuit alleges that defendants throughout the Class Period made false and/or misleading statements and/or failed to disclose that: (i) defendants created the false impression that they possessed reliable information demonstrating that Regeneron’s Phase III Fianlimab-Libtayo Study was well-poised for success, while minimizing risks to the study’s odds of achieving its primary endpoint and its overall statistical validity arising from the prolonged event rate slowdown; (ii) Regeneron’s preliminary statistical assumptions were fundamentally flawed; (iii) the active treatment arm was failing to achieve meaningful clinical differentiation over standard therapies; and (iv) the trial would ultimately fail to reach statistical significance on its primary endpoint even without overperformance of the control arm.
On April 29, 2026, during Regeneron’s first quarter earnings call, defendants allegedly disclosed that the Phase III Fianlimab-Libtayo Study had been altered, expanding the number of patients in the study eligible for “analysis of progression-free survival.” On this news, the price of Regeneron stock declined more than 6%, according to the complaint.
Then, after-market on May 15, 2026, Regeneron issued a press release allegedly announcing that the “Phase 3 Trial of Fianlimab . . . did not reach statistical significance for the primary endpoint of improvement in progression-free survival (PFS).” On this news, the price of Regeneron stock dropped nearly 10%, according to the complaint.
THE LEAD PLAINTIFF PROCESS: The Private Securities Litigation Reform Act of 1995 permits any investor who purchased or acquired Regeneron common stock during the Class Period to seek appointment as lead plaintiff in the Regeneron class action lawsuit. A lead plaintiff is generally the movant with the greatest financial interest in the relief sought by the putative class who is also typical and adequate of the putative class. A lead plaintiff acts on behalf of all other class members in directing the Regeneron class action lawsuit. The lead plaintiff can select a law firm of its choice to litigate the Regeneron class action lawsuit. An investor’s ability to share in any potential future recovery is not dependent upon serving as lead plaintiff of the Regeneron class action lawsuit.
ABOUT ROBBINS GELLER: Robbins Geller Rudman & Dowd LLP is one of the world’s leading law firms representing investors in securities fraud and shareholder rights litigation. Our Firm ranked #1 on the most recent ISS Securities Class Action Services Top 50 Report, recovering more than $916 million for investors in 2025. This marks our fourth #1 ranking in the past five years. And in those five years alone, Robbins Geller recovered $8.4 billion for investors – $3.4 billion more than any other law firm. With 200 lawyers in 10 offices, Robbins Geller is one of the largest plaintiffs’ firms in the world, and the Firm’s attorneys have obtained many of the largest securities class action recoveries in history, including the largest ever – $7.2 billion – in In re Enron Corp. Sec. Litig.