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 the developmental stage biotech Sarepta Therapeutics (NASDAQ:SRPT) rose by over 50% today after the company announced that the Food and Drug Administration agreed to accept a regulatory filing for the company's experimental Duchenne muscular dystrophy, or DMD, drug eteplirsen.

According to the press release, Sarepta plans on completing the filing by mid-year, meaning that eteplirsen could be reviewed at the same time as BioMarin's (NASDAQ:BMRN) competing drug, drisapersen, sometime this fall. 

So what: Eteplirsen's journey toward a formal regulatory review with the FDA has been a rocky one. In 2013, most onlookers believed the FDA was willing to review eteplirsen, even though the drug had only completed a small midstage study at the time.

Unfortunately for investors and DMD patients alike, the agency said such a filing would be premature, causing shares to crater by over 70% in a single day. Since then, Sarepta's shares have struggled mightily to regain their former glory.

So, investors are undoubtedly cheering the FDA's change of heart today, especially since it could end up becoming a major catalyst for the stock as eteplirsen barrels toward its regulatory review.

Now what: As an orphan drug company with a major late-stage asset like eteplirsen, Sarepta certainly could turn into a red hot buyout target moving forward. After all, orphan drug specialists like Prosensa, NPS Pharmaceuticals, and ViroPharma were all gobbled up by larger pharmas recently, and their respective product pipelines were arguably far weaker than Sarepta's. 

In my view, Sarepta would be a great pick up for either Pfizer or Shire plc. Both of these companies have extremely active rare disease programs, and are almost always on the lookout for buyout targets in the orphan drug arena. Stay tuned!