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 Ferro Corp. (NYSE: FOE) fell 18% on high volume today after the company released earnings.

So what: Sales of $594 million actually topped a $587.5 million estimate from analysts, but earnings and guidance were the focus today. Earnings per share were only $0.27, below estimates of $0.34, and the company said it expects solar installations for 2011 to be about 15% lower than 2010.

Now what: High levels of inventory at customers and a slow first half of the year in the solar market are hurting Ferro in the short term. Like many solar panel manufacturers, Ferro is expecting the second quarter to be the low point, with demand picking up throughout the year. So for long-term investors, this should be a bump in the road. Ferro is solidly profitable in a growing market with a nice stock valuation, so I wouldn't be jumping ship on a day like today.

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