Shares of Sarepta Therapeutics nearly halved on Thursday after the Food and Drug Administration maintained its "negative" outlook on the company's drug for a rare muscle-wasting disorder.
Sarepta stock closed down more than 44 percent.
Sarepta is looking for accelerated approval for eteplirsen to treat a subset of patients with Duchenne muscular dystrophy (DMD).
FDA staff reviewers on Thursday reiterated their discomfort with the drug — raising concerns surrounding the drug's trials, its effectiveness, and the company's statistical analysis.
Scientists in January highlighted similar concerns ahead of a scheduled meeting of an independent panel of experts to the FDA. However, this meeting was postponed due to an inclement weather forecast for Washington.
"At this point ... you're basically giving up all that hope going back to mid-January," Mike Bailey, director of research and chair at FBB Capital Partners, told CNBC.
Entering Thursday trading, the stock was down nearly 50 percent for 2016.
SRPT this year
— CNBC's Evelyn Cheng and Reuters contributed to this report.
Disclosure: Bailey doesn't own Sarepta stock.