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 Valhi (Nasdaq: VHI) rose as much as 22% before ending the session up 18%. Subsidiary NL Industries (NYSE: NL) also rallied on Valhi's strength, probably because of an upbeat assessment issued by the stock ratings arm of

So what: In its report, TheStreet Ratings upgraded Valhi from "hold" to "buy," citing revenue and profit growth, expanding margins, and good cash flow from operations.

Now what: Interestingly, TheStreet's bullish stance is about as far as you can get from the consensus Foolish view. Motley Fool CAPS investors give Valhi just one out of five possible stars in rating the stock. Valuation is the most commonly cited concern. Do you agree? Disagree? Weigh in using the comments box below.

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