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 membrane maker Polypore International (NYSE: PPO) jumped 14% today after an analyst upgrade.

So what: Baird analyst Richard Eastman upgraded the company to outperform and raised his price target to $43. Investors jumped on the news, pushing the stock up to $41.25 and leaving very little upside if Eastman's price target is right.

Now what: Polypore has done a nice job swinging back to a profit, but it still sits at a 26 forward price-to-earnings ratio, making shares pretty expensive. Plus, I can't help but think this analyst is a little late to the party since shares have more than tripled over the past year. I look at today's move with a skeptical eye, and I'd like to see fundamentals move the stock instead of an analyst who is jumping aboard a hot stock.

Interested in more info on Polypore? Add it to your watchlist.

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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