Sarepta Therapeutics shares initially plunged 40 percent Tuesday, a day after a Food and Drug Administration advisory committee voted against recommending the company's Duchenne muscular dystrophy drug.
Sarepta shares closed down 26 percent Tuesday.
On Monday, seven members of the FDA's Peripheral and Central Nervous System Drugs Advisory Committee voted that Sarepta had not provided enough evidence that the drug, eteplirsen, was effective for treating DMD. Three voted that it had, and three abstained.
According to Reuters, the panel found that the drug did not "show substantial evidence of efficacy."
The stock had risen more than 7 percent in premarket trading Monday before an all-day halt.