Regeneron stock rises after a $11 billion class-action trigger
Published on 08/29/2026 at 12:56 | Editorial responsibility: Rafael Müller, Editor-in-Chief AD HOC NEWS
Regeneron Pharmaceuticals, Inc. (US75886F1075) stock closed at $834.04 on August 21, 2026, up $7.40 or 0.90%, while its market value stood at $85.87 billion and trading volume reached 786,839 shares.
A securities class-action filing reported on August 28, 2026 cited the company's Phase 3 melanoma trial reversal, said the market reaction erased $11 billion in market value, and set a September 14, 2026 lead-plaintiff deadline.
Market value and momentum
Regeneron's shares have gained 39.43% over the last 12 months and 23.53% in the past month, while the year-to-date return is 8.05% from the same market snapshot. Those figures frame a stock that remains close to recent highs even after the trial-related legal overhang.
The same market page shows a 5.87% spread from the August 21 close to the session high of $847.00, which leaves room for swings even after a strong multi-week advance.
What the lawsuit says
The complaint says the case centers on Regeneron's Phase 3 study of fianlimab in combination with Libtayo for metastatic or locally advanced melanoma, and it links the filing to the later disclosure that the trial did not reach statistical significance on progression-free survival.
For investors, the key comparison is concrete: the legal narrative points to an $11 billion market-cap hit, while the stock's latest close still leaves Regeneron valued at $85.87 billion.
Pipeline context
Libtayo is the product name that appears in the filing and remains the company's most visible oncology franchise in this dispute. The trial's primary endpoint was progression-free survival, which is the metric now at the center of the case.
Closing view
Regeneron stock ended the latest session at $834.04, with the market cap at $85.87 billion as of August 21, 2026.
Fact box
Company: Regeneron Pharmaceuticals, Inc.
ISIN: US75886F1075
Ticker: REGN
Exchange: Nasdaq
Price (as of August 21, 2026, 4:00 p.m. ET): $834.04 USD
Market cap: $85.87 billion (as of August 21, 2026)
Sector / Industry: Health Care / Biotechnology
Index membership: S&P 500
More on Regeneron stock
Regeneron Pharmaceuticals, Inc. is a biotechnology company with a broad drug portfolio spanning eye care, immunology, and oncology.
