Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

Stock market investors got a nasty surprise on Friday, as major-market benchmarks dropped 2% on rising concerns about emerging-market economies. Yet, even the general fear in the market wasn't enough to fully explain the much larger drops that Kansas City Southern (NYSE:KSU), International Game Technology (NYSE:IGT), and First Niagara Financial (NASDAQ:FNFG) suffered today.

Kansas City Southern sank 15% after the railroad posted earnings and revenue growth that fell short of what investors had hoped to see. A rise of 8.3% in sales on a 24% bump in net income seemed solid, especially as an 18% rise in intermodal revenue was able to overcome a plunge in coal revenue, which was down 24% from year-ago levels. But a $0.07 per share shortfall on its earnings-per-share results left Kansas City Southern shareholders feeling uncomfortable with the rich valuations on the railroad stock, and they therefore retreated to produce more margin of safety for future quarters.

International Game Technology also dropped 15% on a poor quarterly report, with revenue rising just 2%, and earnings per share missing estimates by $0.05. Moreover, the gaming-equipment company guided adjusted earnings estimates for the fiscal 2014 year down to the lower end of its previous range. Unlike Kansas City Southern, though, International Game Technology's valuations leave much more room for value investors to bet on a turnaround.

First Niagara Financial fell 12% as the regional bank gave poor guidance for the full fiscal year. The company saw modest growth in loans and deposits, and nonperforming loans stayed at relatively low levels. But the real question is whether First Niagara will be able to finally get the full value of the nearly 200 bank branches it bought from HSBC (NYSE:HSBC) back in 2012. With challenging economic conditions in the bank's Northeast region, though, it's understandable that First Niagara is taking longer than shareholders would like to reap the benefits of that acquisition.