Idenix Shares Plunged: What You Need to Know

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 (NAS: IDIX) are plunging today, down by 16% at the low, after competitor Pharmasset (NAS: VRUS) discontinued use of one of its experimental drugs due to safety concerns.

So what: Pharmasset's experimental hepatitis C drug PSI-938 reported complications with liver function, although the developments aren't expected to interfere with Gilead Sciences' (NAS: GILD) planned acquisition of the company. Idenix also has a hepatitis C drug in its pipeline, which is the company's current focus.

Now what: The news is causing concern among some hepatitis C drugmakers, including Inhibitex (NAS: INHX) , which is also seeing downside today. Interestingly, rival Vertex Pharmaceuticals (NAS: VRTX) is seeing healthy gains, with setbacks for PSI-938 considered positive for Vertex. Idenix's and Inhibitex's hepatitis C drugs are more similar to Pharmassets, which is causing investors to flee for cover.

Interested in more info on Idenix? Add it to your watchlist byclicking here.

At the time thisarticle was published Fool contributorEvan Niuholds no position in any company mentioned.Click hereto see his holdings and a short bio.Motley Fool newsletter serviceshave recommended buying shares of Gilead Sciences and Vertex Pharmaceuticals. Try any of our Foolish newsletter servicesfree for 30 days. We Fools may not all hold the same opinions, but we all believe thatconsidering a diverse range of insightsmakes us better investors. The Motley Fool has adisclosure policy.

Copyright © 1995 - 2011 The Motley Fool, LLC. All rights reserved. The Motley Fool has a disclosure policy.