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 hepatitis-C-focused biotech technology company Idenix Pharmaceuticals (Nasdaq: IDIX) fell as much as 12% -- its third such major drop since August began -- after noting the Food and Drug Administration was placing a halt on another one of its drugs in development.

So what: Earlier this month, the FDA put an indefinite halt on IDX184, Idenix's lead compound, due to complications arising from Bristol-Myers Squibb's (NYSE: BMY) now-canceled hepatitis C drug BMS-986094. Today's halt on IDX19368 is due to the fact that all three drugs are nucleotide inhibitors and work in the same method. Enough concern exists from the FDA's perspective with regard to adverse side effects on patients' hearts, that any further research has been postponed.

Now what: Another day, another setback for Idenix. Gilead Sciences (Nasdaq: GILD) currently has the clear path to developing the first FDA-approved non-interferon-based hepatitis C drug based on its efficacy and safety profile. In addition to competing with other developmental non-interferon-based treatments, Idenix is also going to need to unseat both the leading interferon-based hepatitis C drug, Incivek, produced by Vertex Pharmaceuticals, as well as Merck's Victrelis to a lesser extent. With Idenix already behind Gilead in development and now with two trials halted indefinitely, I don't see how things are going to get any better for Idenix.

Craving more input? Start by adding Idenix Pharmaceuticals to your free and personalized Watchlist so you can keep up on the latest news with the company.