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 filtration technology specialist Polypore International (NYSE: PPO) were getting slammed today, falling as much as 15% in intraday trading after the company reported fourth-quarter results.

So what: On an absolute basis, it was hard to say that the results from the fourth quarter looked particularly poor. Revenue increased 13% from a year ago to $191 million, while adjusted earnings per share had an even larger 35% jump to $0.58. But alas, Wall Street had expected even better numbers. The average analyst estimate saw the company earning an adjusted $0.59 per share on $196 million in revenue.

Now what: When a "high-growth" company doesn't grow as much as investors expect, it's bound to foster disappointment. And that disappointment only likely grew when investors saw the company's outlook. Management pointed to "headwinds" that started in the fourth quarter and said that the first quarter's results will be below last year's. The company is still expecting full-year growth, but without any numbers around that growth, investors are left wondering whether the company will be just inching ahead in 2012.

Still, management stressed Polypore's long-term view and the positive signs that this is an attractive market to be involved in. And after today's drop, Polypore shares are trading at right around 16 times trailing earnings -- a level that hardly suggests excessive optimism.

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