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 operator Kansas City Southern (NYSE: KSU) fell 10% on Tuesday after its quarterly revenue came in below Wall Street expectations.

So what: While the company's fourth-quarter profit rose a whopping 85%, a big miss on the top line -- $530.3 million versus the consensus of $550.3 million -- is triggering fears of a looming slowdown. Of course, KCS shares have been on fire over the past few months -- up about 45% since late September -- so Mr. Market might have just set the expectations bar a little on the high side.

Now what: I'd look into this pullback as a possible buying opportunity. "KCS continues to have abundant growth prospects and is very well-positioned to be a leading growth company in the transportation industry," said CEO David Starling. "We believe that in 2012, KCS will continue on a growth trend similar to that of the past year with mid-single digit increases in volumes and pricing." When you consider that KCS' Mexican assets make it a particularly tasty takeover target to boot, the stock seems like a pretty decent bet.

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

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days.

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