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 diagnostic-test maker Gen-Probe (Nasdaq: GPRO) rocketed up today, gaining as much as 20% in intraday trading on heavier-than-average volume.

So what: Bloomberg reported today that Gen-Probe has hired investment bank Morgan Stanley (NYSE: MS) to manage a sale process and noted that bids are expected in the next couple of weeks. The article suggested that Novartis (NYSE: NVS), Thermo Fisher Scientific (NYSE: TMO), Danaher (NYSE: DHR), and Life Technologies (Nasdaq: LIFE) could be among the bidders.

Now what: As I noted yesterday with InterMune, this kind of news tends to get traders and short-term investors very excited. However, speculation on potential buyouts can often end in disappointment if nothing ever pans out. Longer-term investors would be well-advised to continue focusing on the prospects for Gen-Probe as a stand-alone company and leave the rumors to the traders.

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Fool contributor Matt Koppenheffer does not have a financial interest in any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.