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 drug developer Orexigen Therapeutics (Nasdaq: OREX) were in a death spiral today, losing as much as 34% in intraday trading on heavy volume.

So what: On Wednesday, Orexigen's stock jumped after the company announced it would be providing a regulatory update at the end of the week. At the time I wrote: "However, the lack of substantive news today means that investors are just assuming what Friday's announcement will bring. And as the saying goes, assuming makes an ... well, you know how it goes."

Unfortunately, the optimism was premature as the company's press release today said that it will be halting the development process for its obesity drug Contrave in the U.S. until it can get more clarity on the approval process from the Food and Drug Administration.

Now what: In Orexigen's view, the FDA is demanding that the company run a trial that would be of greater scope and collect more data than is actually needed to address the FDA's concerns about Contrave. Furthermore, the FDA Division of Metabolic and Endocrinologic Products will be reviewing its assessment procedures for obesity drugs in 2012 and so the path to approval is even foggier until then.

The company said it will turn its focus to opportunities for its drugs outside of the U.S., but it seems unlikely that investors will get too excited unless a glimmer of hope returns that Contrave could be approved on its home shores.

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Fool contributor Matt Koppenheffer does not have a financial interest in any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or Facebook. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.