Portnoy Law Firm Announces Class Action on Behalf of Regeneron Pharmaceuticals, Inc. Investors
LOS ANGELES, July 27, 2026 (GLOBE NEWSWIRE) -- The Portnoy Law Firm advises Regeneron Pharmaceuticals, Inc.,
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LOS ANGELES, July 27, 2026 (GLOBE NEWSWIRE) — The Portnoy Law Firm advises Regeneron Pharmaceuticals, Inc., (“Regeneron” or the “Company”) (NASDAQ: REGN) investors of a class action on behalf of investors that bought securities between August 1, 2025 and May 15, 2026, inclusive (the “Class Period”). Regeneron investors have until September 14, 2026 to file a lead plaintiff motion.
Investors are encouraged to contact attorney Lesley F. Portnoy, by phone 310-692-8883 or email: lesley@portnoylaw.com, to discuss their legal rights, or join the case via https://portnoylaw.com/regeneron-pharmaceuticals-inc. The Portnoy Law Firm can provide a complimentary case evaluation and discuss investors’ options for pursuing claims to recover their losses.
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 Portnoy Law Firm represents investors in pursuing claims caused by corporate wrongdoing. The Firm’s founding partner has recovered over $5.5 billion for aggrieved investors. Attorney advertising. Prior results do not guarantee similar outcomes.
Lesley F. Portnoy, Esq.
Admitted CA, NY and TX Bar
lesley@portnoylaw.com
310-692-8883
www.portnoylaw.com
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