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 TPC Group (Nasdaq: TPCG), a producer of specialty chemicals, fell more than  12% on more than double its average daily volume before closing down around 8%.

So what: While no there was no company-specific news to cause the drop, TPC may have suffered collateral damage at the hands of Kraton Performance Polymers (NYSE: KRA), another specialty chemist that fell more than 30% after missing earnings estimates.

Now what: Second-quarter results are due in a week. In the meantime, shares of TPC trade for roughly one-third the long-term earnings growth rate analysts expect, resulting in a 0.35 PEG ratio. Unless Wall Street is off the map in its estimates, this stock is a bargain right now. Do you agree? Disagree? Weigh in using the comments box below.

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Fool contributorTim Beyers is a member of theMotley Fool Rule Breakers stock-picking team. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim'sportfolio holdings andFoolish writings, or connect with him on Google+ or Twitter, where he goes by @milehighfool. You can also get his insightsdelivered directly to your RSS reader.

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