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 Idenix Pharmaceuticals (NASDAQ: IDIX), a clinical-stage biopharmaceutical company developing therapies to treat human viral diseases, soared 44% after reporting its third-quarter results and providing an update on its pipeline.

So what: For the quarter, Idenix reported just $19,000 in revenue compared to $32.3 million in the year-ago period while reporting a net loss of $34 million, or $0.25 per share, compared to a profit of $4.3 million, or $0.03, last year. Comparatively, the loss was $0.01 worse than expected, and revenue was definitely lower than the Street's estimates. But investors seem keen on focusing on the company's pipeline update. Although IDX20963 remains on hold, Idenix announced that IDX21437 has received approval to enter clinical trials in Canada and Belgium, and that all patients had completed enrollment in the first phase of its mid-stage trial involving samatasvir, its NS5A inhibitor.

Now what: The big move today, plainly, is about investor optimism that Idenix's pipeline isn't dead after all. As for me, I still consider Idenix a long shot to succeed given just how far it has fallen behind its competitors in treating hepatitis C. You have both Gilead Sciences (NASDAQ: GILD), which has already submitted sofosbuvir for approval with the Food and Drug Administration (and received a unanimous 15-0 vote for recommended approval from the FDA's panel last month), and AbbVie's (NYSE: ABBV) direct-acting antiviral combo, which is a breakthrough-therapy-designated drug that should be in front of the FDA sometime next year. Idenix is years behind its peers, and it's going to be burning up precious cash trying to catch up. I would suggest using today's pop as a reason to possibly consider hitting the exits.

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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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