Daily close, T-120 (5/2/25) through T+5. Run-up high $614.79 on 5/26/25, low $483.07 on 6/10/25 (T-120 to T-1). FDA decision 10/17/25. Historical price action, not a forecast.
Positioning before the decision
On Oct 3, 2025, 14 days before the decision date, at-the-money options priced a move of ±7.2% through Oct 24, 2025 (the first listed expiry after the decision; ATM implied volatility 37%). The stock closed +1.6% at the first close across the decision and +1.1% five trading days on. A straddle priced weeks out covers ordinary movement plus the event, so this is the move the options market priced through that expiry, not the event-implied move alone. How this compares across 1,000+ decisions.
Decision facts
FDA decision date2025-10-17
DrugSolnerstotug (formerly SNS-101) with Libtayo - (VISTA)
IndicationOne microsatellite stable (MSS) endometrial cancer
Was Solnerstotug (formerly SNS-101) with Libtayo - (VISTA) approved by the FDA?
Not in this review cycle. On October 17, 2025 the FDA issued a Complete Response Letter, declining to approve the application for Solnerstotug (formerly SNS-101) with Libtayo - (VISTA) in its current form. A CRL is not final; the primary source is linked on this page.
What was Solnerstotug (formerly SNS-101) with Libtayo - (VISTA) under FDA review for?
The application covered One microsatellite stable (MSS) endometrial cancer. The FDA declined to approve the application in its current form on October 17, 2025.
How did REGN stock react to the FDA decision?
On the decision day REGN moved +1.6%. That is the recorded reaction to this specific event -- historical measurement, not a prediction, and not investment advice.