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 firm Vertex Pharmaceuticals (Nasdaq: VRTX) dipped as much as 15% following a clarification from the company regarding the efficacy of its cystic fibrosis drug.

So what: In May, Vertex rallied considerably on news that its cystic fibrosis drug, Kalydeco, showed statistically positive results in mid-stage studies. However, news released today from Vertex demonstrates that Kalydeco may not be as effective as the original data had implied. Vertex cited a misinterpretation on its part and with its analysis vendor as the reason for the data revision. Wall Street's other gripe is the data between the two sets isn't very comparable, making an assessment of this revision even more difficult.

Now what: Today's news took Wall Street by surprise as things looked to be going Vertex's way. Although sales of Vertex's FDA-approved hepatitis-C drug, Incivek, have likely peaked, it's Kalydeco that appeared to be the icing on the cake for a potential pharmaceutical suitor. Today's news probably takes near-term buyout speculation off the table until we get more discernible data from 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.