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 special chemicals maker Chemtura (NYSE: CHMT) fell as much as 11% today after the company said it saw a weak fourth quarter coming.

So what: Chemtura announced preliminary third-quarter sales of $773 million and earnings before taxes of $22 million, a 144% increase over last year. But cautious comments about the fourth quarter have sent shares tumbling as customers fret about the macroeconomic picture.

Now what: Uncertainty is reigning supreme right now as no one is quite sure how issues in Europe and U.S. demand will develop, so the market tends to react strongly to this kind of news.

On the plus side, Chemtura did announce a $50 million share repurchase plan, and today's drop might provide a nice discount for the buyback. I am seeing this as a buying opportunity, with the new buyback program and shares trading at just over 7 times forward earnings estimates.

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