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 biotechnology company Vertex Pharmaceuticals (NASDAQ:VRTX) dropped as much as 17% after the company reported much-worse-than-expected third-quarter results.

So what: For the quarter, Vertex reported a 40% decline in Incivek sales over the year-ago period and a loss of $0.27 per share -- which includes a $57.6 million charge related to expected future payments to Alios BioPharma. Vertex did stick with its full-year forecast for Incivek sales of $1.1 billion to $1.25 billion; however, it made it clear that it's begun its focus on creating the next generation of hepatitis-C treatments that aren't interferon-based. Vertex announced that it'll be testing one of its experimental hepatitis-C therapies, VX-135, in two separate trials with Johnson & Johnson's (NYSE:JNJ) simeprevir, and GlaxoSmithKline's (NYSE:GSK) GSK2336805.

Now what: It's a little disconcerting to see how quickly Incivek sales are falling off, but I think it's also worth noting that few alternatives to Incivek are likely to hit the market anytime soon. Gilead Sciences' (NASDAQ:GILD) GS7977 when combined with Bristol-Myers Squibb's (NYSE:BMY) daclatasvir, appears to be the strongest combination candidate for hepatitis-C approval, but it may be years before it takes significant share from Incivek. Personally, I think today's fall could be a buying opportunity in Vertex.

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

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.