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: Polypore's (NYSE: PPO) profit popped 85% in comparison with last year, but even that wasn't enough to save the company's stock from a selloff Tuesday. Polypore shares closed down 10% on the day.

So what: Both revenues and profits ($0.63 per share, adjusted) exceeded Wall Street's estimates for the fiscal second quarter. Problem was, Polypore warned that next quarter might not be quite so fabulous as the company invests $105 million to expand production of membranes used to manufacture lithium-ion batteries.

Now what: You wouldn't think that was such bad news as to cause a 10% selloff, though. What Polypore actually said yesterday was that investments to expand capacity might "constrain" its "ability to exceed our recent performance" (emphasis added.) What that sounds like to me is that Polypore is promising no more than $0.63 per share in Q3 -- but all Wall Street is looking for is $0.49 per share.

Then again, with the stock fetching nearly 40 times earnings already, and having nearly tripled in price over the past year, maybe investors were just looking for an excuse to cash out their profits.

Think there's more room to run at Polypore? Add the stock to your Fool Watchlist.

Fool contributor Rich Smith does not own (or short) shares of Polypore. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.