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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