Page updated ·next FDA decision on the calendar·Data as of Nov 5, 2026 9:00 PM ET
Price into the decision (T-120)
Daily close, T-120 (8/9/24) through T+5. Run-up high $210.7 on 8/9/24, low $140.55 on 1/20/25 (T-120 to T-1). FDA decision 1/26/25. Historical price action, not a forecast.
Positioning before the decision
On Jan 10, 2025, 16 days before the decision date, at-the-money options priced a move of ±7.2% through Jan 31, 2025 (the first listed expiry after the decision; ATM implied volatility 37%). The stock closed +1.8% at the first close across the decision and -1.6% 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 date2025-01-26
DrugLEQEMBI (lecanemab-irmb)
IndicationIV Maintenance Dosing for Alzheimer’s disease
13F reports list long positions in common stock at quarter end, are due 45 days later, and show no short positions or later trades. Notes, warrants and other instruments are not counted as shares.
Questions
Was LEQEMBI (lecanemab-irmb) approved by the FDA?
Yes. The FDA approved the application for LEQEMBI (lecanemab-irmb) on January 24, 2025, per the FDA's own record. The company announced it on January 26, 2025. The primary source is linked on this page.
What was LEQEMBI (lecanemab-irmb) under FDA review for?
The application covered IV Maintenance Dosing for Alzheimer’s disease. The FDA approved the application on January 26, 2025.
How did BIIB stock react to the FDA decision?
On the decision day BIIB moved +1.8%. That is the recorded reaction to this specific event. Historical measurement, not a prediction, and not investment advice.