REGENERON ALERT: Bragar Eagel & Squire, P.C. is Investigating Regeneron Therapeutics, Inc. on Behalf of Long-Term Stockholders and Encourages Investors to Contact the Firm

Bragar Eagel & Squire, P.C., a nationally recognized shareholder rights law firm, is investigating potential claims against Regeneron Therapeutics, Inc. (NASDAQ:REGN) on behalf of long-term stockholders following a class action complaint that was filed against Regeneron on July 16, 2026 with a Class Period from August 1, 2025, and May 15, 2026. Our investigation concerns whether the board of directors of Regeneron have breached their fiduciary duties to the company.

The complaint alleges that the Company and its executives violated federal securities laws by making false and/or misleading statements and/or failing to disclose the true state of Regeneron's Phase III Fianlimab-Libtayo Study; notably, that its preliminary statistical assumptions were fundamentally flawed, that the active treatment arm was failing to achieve meaningful clinical differentiation over standard therapies, and that the trial would ultimately fail to reach statistical significance on its primary endpoint even without overperformance of the control arm.

Plaintiff alleges that April 29, 2026, during Regeneron's first quarter earnings call, defendants disclosed 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's common stock declined from a closing market price of $731.77 per share on April 28, 2026, to $686.36 per share on April 29, 2026, a decline of about 6.2% in the span of just a single day.

Then, after-market on May 15, 2026, Regeneron announced 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's common stock declined from $698.25 per share on May 15, 2026, to $629.68 per share on May 18, 2026, a decline of about 9.8% in the span of one day.

If you are a long-term stockholder of Regeneron, have information, would like to learn more about these claims, or have any questions concerning this announcement or your rights or interests with respect to these matters, please contact Brandon Walker or Melissa Fortunato by email at [email protected] , by telephone at (212) 355-4648, or by filling out this contact form . There is no cost or obligation to you.