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 building products maker USG Corporation (NYSE: USG) jumped 12% today after announcing earnings.

So what: Fourth-quarter revenue was up 12.3%, to $915.0 million, and adjusted earnings per share were $0.19. Analysts were only expecting $906.7 million in revenue and $0.10 per share in earnings, so the company easily topped Wall Street's numbers. 

Now what: Residential building helped demand in the fourth quarter as housing starts hit an annual pace of 1.1 million in November, the highest since 2007. Shares aren't terribly cheap at 19 times forward earnings, but with performance like this, the company could be a steal for investors. Watch for continued momentum in residential and commercial building, because that's what will lead to continued outperformance for USG.