Important Notice Regarding Alleged Phase III Fianlimab-Libtayo Clinical Trial Risk Misrepresentations. The lawsuit alleges Regeneron investors overpaid while the Company characterized slowing event accrual as potentially favorable, even as the study allegedly faced heightened risk of failing its primary endpoint.

NEW YORK, July 30, 2026 /PRNewswire/ — SueWallSt notifies investors in Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) that a class action lawsuit has been filed on behalf of shareholders who purchased securities between August 1, 2025 and May 15, 2026. Find out if you could qualify to recover your losses. You may also contact Joseph E. Levi, Esq. at jlevi@SueWallSt.com or (888) SueWallSt.

Regeneron shares declined approximately 13.95%, or $102.09 per share, from the Class Period high through the final disclosure-related decline. Applications to serve as lead plaintiff must be filed by September 14, 2026.

The Alleged Clinical Trial Risk Securities Fraud Methodology

According to the lawsuit, Regeneron provided investors with materially positive information about the Phase III Fianlimab-Libtayo Study while allegedly mischaracterizing the risk created by a prolonged slowdown in progression-free survival event accrual. The complaint alleges that investors were not told that preliminary statistical assumptions were flawed and that the trial was at increased risk of missing statistical significance.

The lawsuit contends that the Company framed the slowdown as consistent with durable efficacy in the active treatment arms, rather than as a warning sign that the study’s statistical design and endpoint assumptions were under pressure.

How Event Accrual Allegedly Affected Investor Expectations

The Phase III Fianlimab-Libtayo Study tested a LAG-3 inhibitor combination as a first-line treatment for advanced melanoma. The complaint alleges that Regeneron’s optimistic discussion of delayed event accrual caused investors to form expectations about the program that was not supported by the study’s actual risk profile.

“This case presents important questions about clinical-trial risk disclosure obligations in the biotechnology sector, particularly where investors are told that delayed events may reflect durable treatment activity. The complaint alleges that shareholders were not given a fair picture of the study’s statistical risks before the program missed its primary endpoint.” — Joseph E. Levi, Esq.

Key Clinical Trial Risk Allegations for Shareholders

• The complaint alleges that the slowdown in event accrual was presented as potentially favorable to the active treatment arms.
• The lawsuit contends that the Phase III study’s preliminary statistical assumptions were materially flawed.
• Plaintiffs allege that the active treatment arms were not demonstrating the clinical separation investors were led to expect.
• The action claims that the study’s risk of failing its primary endpoint was understated during the Class Period.
• Regeneron later announced that the trial did not reach statistical significance for improvement in progression-free survival.

Submit your information here or call (888) SueWallSt.

WHY SUEWALLST: SueWallSt is powered by Levi & Korsinsky LLP. Levi & Korsinsky LLP has established itself as a nationally-recognized securities litigation firm that has secured hundreds of millions of dollars for aggrieved shareholders and built a track record of winning high-stakes cases. The firm has extensive expertise representing investors in complex securities litigation and a team of over 70 employees to serve our clients. For seven years in a row, Levi & Korsinsky has ranked in ISS Securities Class Action Services’ Top 50 Report as one of the top securities litigation firms in the United States.

Frequently Asked Questions About the REGN Lawsuit

Q: What is the REGN class action lawsuit about? A: A securities class action has been filed against Regeneron Pharmaceuticals, Inc. (NASDAQ: REGN) alleging materially false and misleading statements between August 1, 2025 and May 15, 2026. Shares fell approximately 13.95% after the Company disclosed a protocol expansion for progression-free survival analysis and later announced that the Phase 3 Fianlimab trial did not reach statistical significance. Investors who purchased shares during the Class Period and suffered losses may be eligible to seek compensation.

Q: What specific misstatements does the REGN lawsuit allege? A: The complaint alleges Regeneron made materially false or misleading statements regarding the Phase III Fianlimab-Libtayo Study, including statements that allegedly minimized the clinical and statistical risk associated with slowing event accrual. When the protocol change and later trial failure were disclosed, the stock price declined sharply.

Q: What court was the REGN class action filed in? A: The case was filed in the United States District Court for the Southern District of New York, governed by the Private Securities Litigation Reform Act of 1995.

Q: What is a lead plaintiff and why does it matter? A: A lead plaintiff is the investor appointed by the court to represent the entire class. Lead plaintiffs are typically investors with the largest documented losses. Being appointed does not increase individual recovery but gives direct oversight of how the case is run.

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 eligibility.

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 during the Class Period and sold at a loss may still be eligible to participate.

Q: Do I need to go to court or give testimony? A: No. The overwhelming majority of class members never appear in court or give depositions. If there is a settlement or recovery, eligible class members generally submit a claim form to seek their portion.

CONTACT:
Levi & Korsinsky, LLP
Joseph E. Levi, Esq.
33 Whitehall Street, 27th Floor
New York, NY 10004
jlevi@SueWallSt.com
Tel: (888) SueWallSt
Fax: (212) 363-7171

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