REGN SHAREHOLDER INVESTIGATION: SueWallSt Investigates Regeneron Pharmaceuticals for Possible Securities Law Violations

Regeneron executives pointed to optimistic outcomes for a study that was revealed to have failed to achieve its primary endpoint only two months later; shares dropped sharply when the results came in.

NEW YORK, May 19, 2026 /PRNewswire/ -- Regeneron Pharmaceuticals (NASDAQ: REGN) shareholders saw the stock decline more than 10% when the market opened on May 18, 2026 after investors digested the weekend news that Regeneron's Phase 3 melanoma trial of Fianlimab + Libtayo failed to meet its primary endpoint versus Merck's Keytruda (pembrolizumab). Those who lost money on REGN are encouraged to submit their information to SueWallSt. You may also contact Joseph E. Levi, Esq. via email at [email protected] or by telephone at (888) SueWallSt.

In March, the Senior Vice President of Investor Relations, Ryan Crowe, told investors management was "hopeful" for the LAG-3 study to show positive differentiators for Fianlimab in combination with Libtayo, such as a low to mid-teens median PFS" and an "opportunity to have … a statistically significant, clinically meaningful benefit on OS."

A little more than two months later, on May 16, 2026, Regeneron disclosed that fianlimab + Libtayo did not meet the trial's primary endpoint against Keytruda. The upbeat language on potential outcomes offered on March 10, 2026 failed to stress the risk of the trial failure. The stock fell sharply on the revelation.

Shareholders who purchased REGN and suffered losses may click here to discuss their legal rights with SueWallSt. You may also reach Joseph E. Levi, Esq. at [email protected] or (888) SueWallSt.

SueWallSt | Top 50 Securities Firm | (888) SueWallSt | www.suewallst.com

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 made materially false or misleading statements regarding the progress and expected outcome of its Phase 3 melanoma trial of fianlimab + Libtayo. When the trial failure was disclosed, 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 SueWallSt for a free, no-obligation evaluation at [email protected] or (888) SueWallSt. No immediate action is required to remain eligible to participate in the investigation.

Q: What happens after I contact SueWallSt?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:
SueWallSt
Joseph E. Levi, Esq.
Ed Korsinsky, Esq.
33 Whitehall Street, 27th Floor
New York, NY 10004
[email protected]
Tel: (888) SueWallSt
Fax: (212) 363-7171

SOURCE SueWallSt.com