Page updated ·next FDA decision on the calendar·Data as of Oct 11, 2026 9:31 PM ET
✓ APPROVED
MIPLYFFA (MY-PLY-FAH) (arimoclomol) was approved by the FDA for Niemann-Pick disease Type C (NPC); the approval was announced on June 8, 2026.
XOMA Royalty Corporation, MIPLYFFA (MY-PLY-FAH) (arimoclomol) · Niemann-Pick disease Type C (NPC).
Run-up into the decision (T-120 → T+5)
Daily close, T-120 (12/22/25) through T+5. Run-up high $42.4 on 6/4/26, low $22.89 on 2/13/26 (T-120 to T-1). FDA decision 6/8/26. Historical price action, not a forecast.
Positioning before the decision
On May 20, 2026, 19 days before the decision date, at-the-money options priced a move of ±10.4% through Jun 18, 2026 (the first listed expiry after the decision; ATM implied volatility 78%). The stock closed -0.4% at the first close across the decision and -0.7% 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.
Key facts
FDA decision date2026-06-08
OutcomeApproved
Drug / candidateMIPLYFFA (MY-PLY-FAH) (arimoclomol)
CompanyXOMA Royalty Corporation
120-day run-up (T-120→T-1)+66.9%
Every FDA approval letter and released Complete Response Letter we hold, by FDA action date: FDA approval letters.
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