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 railroad-car maker Greenbrier (NYSE: GBX) rose more than 21% in early trading after reporting strong fourth-quarter results.

So what: Citing higher demand for railcars, Greenbrier earned $0.52 a share of adjusted earnings, beating the consensus by $0.10. Revenue soared 142% to $442.7 million.

Now what: Most importantly, management expects further gains in the year ahead. Greenbrier expects revenue and adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA) to be "significantly higher" in 2012. Do you agree? Would you buy shares of Greenbrier Companies at current prices? Please weigh in using the comments box below.

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Fool contributor Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Google+ or Twitter, where he goes by @milehighfool. You can also get his insights delivered directly to your RSS reader.

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