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 drug developer InterMune (Nasdaq: ITMN) jumped as much as 11% in intraday trading on heavier-than-average trading volume.

So what: The rumor mill is a-cranking and InterMune is at the center. Bloomberg reported today that InterMune is working with Goldman Sachs on a potential sale of the company. An analyst quoted by Bloomberg speculated that GlaxoSmithKline (NYSE: GSK), AstraZeneca (NYSE: AZN), Novartis (NYSE: NVS), and Teva Pharmaceutical Industries (Nasdaq: TEVA) could be among the potential bidders.

Now what: Speculation and rumor can be the stuff that dreams are made of for short-term traders, but they should take up precious little space in the long-term investor's playbook. Bloomberg's article specifically noted that some buyers have balked at the sale price that InterMune is looking for, so it's quite possible that nothing comes of this sale process. For that reason, investors may be best off evaluating the company based on its longer-term prospects rather than chasing today's pop.

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GlaxoSmithKline, Novartis AG, and Teva Pharmaceutical Industries are Motley Fool Global Gains selections. The Fool owns shares of GlaxoSmithKline and Teva Pharmaceutical Industries. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

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