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 Inhibitex (Nasdaq: INHX), which doubled on Friday, continued their climb Monday, after the company reported strong clinical data for its in-development hepatitis C treatment. The stock popped 24% in early trading before closing up around 14%.

So what: As my Foolish colleague David Williamson points out, Inhibitex's oral drug -- code-named INX-189 -- could threaten to displace more complex treatments from Vertex Pharmaceuticals (Nasdaq: VRTX) and Merck (NYSE: MRK). Vertex, in particular, closed off 9%.

Now what: Action in Inhibtex peer Pharmasset (Nasdaq: VRUS), which closed up more than 4%, could help explain the Vertex sell-off. At the very least, it suggests that investors believe oral treatments are the future for hepatitis C sufferers. Do you agree? Would you buy shares of Inhibitex at current prices? Please weigh in using the comments box below.

Interested in more information about Inhibitex? Add it to your watchlist.