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.

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

Fool contributor Anders Bylund holds no position in any of the companies discussed here, though he's kicking himself for selling his modest Kronos position last summer -- some 210% of missed gains ago. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool is investors writing for investors.