Ultragenyx hits record low after rare disease drug trial failure

Ultragenyx Pharmaceutical

03/09/2026 16:00

Updates
** Shares of Ultragenyx Pharmaceutical RARE.O fall 44.5% to an all-time low of $14.74
** Stock set for its worst single-day percentage decline on record and breaks below its previous 52-week low of $18.29 reached in March 2026
** Co on set to wipe out roughly $1.2 billion in market value, if losses hold
** Co's drug apazunersen failed to meet its main goal in a late-stage trial for Angelman syndrome, a condition that affects the nervous system and impairs typical brain development in childhood
** The drug did not show meaningful improvement in children's cognitive abilities or overall development compared with placebo
** The readout is "unambiguously negative" and the failure "raises risk for competitors" like Ionis IONS.O, who have their own similar late-stage Angelman trials ongoing - Jefferies analyst
** More than 11.2 mln shares traded, nearly 5 times the stock's 30-day average volume
** As of last close, stock up 15.4% YTD

 (Reporting by Kamal Choudhury in Bengaluru)
 ((Kamal.Choudhury@thomsonreuters.com;))