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 Polypore International (NYSE: PPO) dropped as much as 18% early today after the company that makes filtration membranes released earnings.

So what: Revenue was up 10% in the third quarter to $151.7 million and net income rose to $12.4 million, or $0.27 per share. This met analysts' expectations, but apparently investors in the company were looking for more.

Now what: Polypore has a history of crushing expectations, so merely meeting expectations may not be enough. Doubling profit and increasing sales are usually great during earnings season, so I think this sell-off is an overreaction considering the strong results. With positive comments from management about demand, I'm buying this dip as an opportunity for investors to get shares on the cheap.

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Fool contributor Travis Hoium does not have a position in any company mentioned. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.

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