Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Sarepta Therapeutics (NASDAQ: SRPT), a biopharmaceutical company focused on RNA-based therapies, fell as much as 16% after updating its status in an attempt to gain an accelerated approval for its Duchenne muscular dystrophy drug, eteplirsen.

So what: In a press release after the bell yesterday, Sarepta noted that the Food and Drug Administration requested additional information about its mid-stage clinical results. Specifically, the FDA requested feedback as to why dystrophin – a protein whose production is encouraged by eteplirsen -- would be an acceptable surrogate endpoint and predictor of clinical benefit in patients with DMD. The FDA also requested additional safety data relating to a potential accelerated approval filing. Research firm Leerink Swann took the opportunity to downgrade Sarepta to "market perform" from "outperform" on the news and lower its price target to $41 from $45 on the request for additional data.

Now what: There's really two ways you can look at this. From a negative perspective the FDA is questioning whether there's enough reason to believe that eteplirsen's increased dystrophin production leads to clinical benefits for DMD patients. If Sarepta can't prove this to the satisfaction of the FDA, it'll need to run a phase 3 trial, which is both costly and time consuming. On the other hand, the glass-half-full crowd will see this as a willingness by the FDA to move eteplirsen into an accelerated approval status once Sarepta satisfies its requests. It's a bit early to lean either way, but, if forced to choose, I'm still betting on eteplirsen eventually securing an accelerated approval.

Craving more input? Start by adding Sarepta Therapeutics to your free and personalized watchlist so you can keep up on the latest news with the company.

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Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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