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 business advisor Corporate Executive Board (Nasdaq: EXBD) dropped as much as 14% on heavy volume this morning, erasing about eight months of steady gains in one fell swoop.

So what: This morning's second-quarter report didn't exactly inspire confidence in CEB. Sales rose 8.8% year-over-year to fall just short of Wall Street estimates, while earnings dropped by about 10% and missed analyst targets by 20%.

Now what: Even after this huge drop, CEB still trades at a very generous premium to rivals Korn/Ferry International (NYSE: KFY) and Booz Allen Hamilton (NYSE: BAH). Unlike 93% of our CAPS members with an opinion on the stock, I'm not so sure that CEB deserves any premium at all. Attractive sales growth can't make up for a long-term trend of shrinking margins.

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