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 (10/24/24) through T+5. Run-up high $65.16 on 3/21/25, low $42.57 on 11/26/24 (T-120 to T-1). FDA decision 4/10/25. Historical price action, not a forecast.
Positioning before the decision
On Mar 27, 2025, 14 days before the decision date, at-the-money options priced a move of ±6.1% through Apr 17, 2025 (the first listed expiry after the decision; ATM implied volatility 31%). The stock closed -4.9% at the first close across the decision and -3.0% 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.
Every FDA approval letter and released Complete Response Letter we hold, by FDA action date: FDA approval letters.
Questions
Was VYVGART Hytrulo (efgartigimod) approved by the FDA?
Yes. The FDA approved the application for VYVGART Hytrulo (efgartigimod) on April 10, 2025, per the FDA's own record. The primary source is linked on this page.
How did HALO stock react to the FDA decision?
On the decision day HALO moved -4.9%. That is the recorded reaction to this specific event. Historical measurement, not a prediction, and not investment advice.