Regeneron's executives were optimistic about the potential for fianlimab + Libtayo; when the study failed to produce exepected results, the stock opened down more than 10%.

NEW YORK, May 18, 2026 /PRNewswire/ -- Regeneron Pharmaceuticals (NASDAQ: REGN) shareholders saw significant losses when the stock dropped sharply following the May 16, 2026 disclosure that its Phase 3 melanoma trial of fianlimab + Libtayo failed to meet its primary endpoint versus Keytruda. Investors who lost money on REGN are encouraged to submit their information now to discuss their legal rights. You may also contact Joseph E. Levi, Esq. via email at jlevi@levikorsinsky.com or by telephone at (212) 363-7500.

During healthcare conference presentations in November and December of 2025, Regeneron executives positively highlighted a delay to its LAG-3 study, assuring investors they "believe this is because the test arms are performing well." Regeneron's Senior Vice President of Investor Relations, Ryan Crowe, noted it was just a mere "slowing of event rates" while confirming to investors management still had "a lot of hope and confidence that fianlimab-plus Libtayo can generate a meaningful differentiation against current standards of care."

Shareholders who purchased Regeneron stock and suffered a loss are encouraged to click here to get more information about the REGN investigation. You may also contact Joseph E. Levi, Esq. via email at jlevi@levikorsinsky.com or by telephone at (212) 363-7500.

Levi & Korsinsky, LLP -- Top 50 securities litigation firm (ISS, seven consecutive years). Over 70 professionals. Hundreds of millions recovered.

Frequently Asked Questions About the REGN Investigation

Q: Who is eligible to participate in the REGN investigation?A: Investors who purchased REGN stock or securities and suffered financial losses may be eligible. Eligibility is based on purchase date and documented losses -- not on whether you still hold the shares.

Q: Which statements are being investigated as potentially misleading?A: The investigation concerns whether Regeneron Pharmaceuticals made materially false or misleading statements regarding the potential and progress of its Phase 3 melanoma trial. When the trial failure was revealed, the stock price declined sharply.

Q: What do REGN investors need to do right now?A: Gather brokerage records including purchase dates, share quantities, and prices paid. Contact Levi & Korsinsky for a free, no-obligation evaluation at jlevi@levikorsinsky.com or (212) 363-7500. No immediate action is required to remain eligible to participate in the investigation.

Q: What happens after I contact Levi & Korsinsky?A: An attorney will review your trading history at no cost and provide an initial assessment of your potential recovery.

Q: What if I already sold my REGN shares -- can I still recover losses?A: Yes. Eligibility is based on when you purchased, not whether you still hold the shares. Investors who bought REGN and sold at a loss may still participate in the investigation.

Q: Do I need to go to court or give testimony?A: No. Participating in the investigation does not require court appearances or depositions. If legal action is later pursued, the overwhelming majority of affected investors never appear in court either.

Q: What does it cost me to participate?A: Nothing. Securities investigations and any resulting actions are handled on a pure contingency basis. No upfront fees, no retainer, no out-of-pocket costs.

CONTACT:\

Levi & Korsinsky, LLP\

Joseph E. Levi, Esq.\

Ed Korsinsky, Esq.\

33 Whitehall Street, 27th Floor\

New York, NY 10004\

jlevi@levikorsinsky.com\

Tel: (212) 363-7500\

Fax: (212) 363-7171

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SOURCE Levi & Korsinsky, LLP