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 biopharmaceutical Orexigen Therapeutics (Nasdaq: OREX) more than doubled in early Wednesday trading after winning a Food and Drug Administration panel's backing for its new diet pill, Contrave.

So what: If approved, Contrave would be the first prescription weight-loss pill introduced in more than a decade, with peak sales being estimated at about $1 billion in 2016. The news comes as a particularly welcome surprise for Orexigen shareholders, given that competing treatments from Vivus (Nasdaq: VVUS) (Qnexa) and Arena Pharmaceuticals (Nasdaq: ARNA) (lorcaserin) -- whose shares are also up nicely on the news -- were previously rejected.

Now what: While this win for Orexigen eases some of the worries that have weighed on its shares in 2010, today's 100%-plus gain now has me concerned. With an estimated 68% of American adults being overweight, there's no denying Contrave's blockbuster potential. I'd just feel a lot more comfortable about jumping in when Mr. Market is a little less excited.

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