Ultragenyx hits record low after rare disease drug trial failure
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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, a Jefferies analyst said.
More than 11.2 million shares traded, nearly five times the stock's 30-day average volume.
As of the last close, the stock was up 15.4% year to date.
Shares fall after late-stage trial failure
Shares of Ultragenyx Pharmaceutical RARE.O fell 44.5% to an all-time low of $14.74.
The stock was set for its worst single-day percentage decline on record and broke below its previous 52-week low of $18.29 reached in March 2026.
The company was set to wipe out roughly $1.2 billion in market value, if losses held.
Apazunersen misses main goal in Angelman syndrome study
Ultragenyx'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.
