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 chemicals producer and waste management service provider Valhi (NYSE: VHI) are in the dumps today, metaphorically speaking. Share prices fell as much as 11.2% on a series of heavy volume spikes.

So what: The same shares popped sky-high last week on news of a raised dividend, and have more than doubled since mid-March. Today's action looks a lot like a few large investors converting paper profits into real cash, and who can blame 'em?

Now what: That doesn't necessarily mean that Valhi's tremendous run is over. The raised dividend is a very shareholder-friendly move in itself, and the stock may still be worth more than the sum of its conglomerated parts. After all, Valhi's majority-owned sister companies NL Industries (NYSE: NL) and Kronos Worldwide (NYSE: KRO) have soared even faster than Valhi itself over the last year.

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