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 FactSet Research Systems (NYSE: FDS) have dropped by as much as 11% after the company reported acceptable earnings, but also revenue guidance for next quarter that falls short.

So what: Third-quarter sales rang in at $202.3 million, with adjusted earnings per share of $1.15, representing the first time that FactSet has crossed the $200 million quarterly revenue threshold. That revenue was right on target with expectations while the profit bested the $1.04-per-share consensus estimate.

Now what: CEO Philip Hadley said the economy remains volatile, but the company's strategy of investing in the future is paying off. Annual subscription value rose 9% to $811 million, most of which comes from buy-side clients. The real culprit for the plunge was fourth-quarter guidance, with sales predicted between $204 million and $208 million, which is a tad shy of the $210 million that investors were hoping for.

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