The complaint alleges that Regeneron provided misleading information about the Phase III trial, concealing flaws in statistical assumptions and failing to disclose that the treatment arm lacked clinical differentiation over standard therapies. These omissions reportedly artificially inflated the company’s stock price. Investors were blindsided on April 29, 2026, when the firm disclosed adjustments to the study's progression-free survival analysis, triggering a 6.2% single-day share price drop from $731.77 to $686.36.

Further volatility followed on May 15, 2026, when Regeneron confirmed the trial failed to reach statistical significance for its primary endpoint. The stock fell an additional 9.8% over the next trading session, sliding from $698.25 to $629.68. The Gross Law Firm is managing the registration process for affected shareholders, offering portfolio monitoring for those who join the action. Participation does not require appointment as a lead plaintiff, and there are no upfront costs for investors involved in the case.