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 Chinese travel expert (Nasdaq: CTRP) were flying high today, gaining as much as 11% in intraday trading after the company reported first-quarter results.

So what: Getting straight to the numbers, for the first quarter, Ctrip's revenue grew 19% from a year ago, to $145 million, while earnings per share came in at $0.18, which was down about 8% from last year. Per-share earnings just missed the $0.19 expectation of Wall Street analysts. The quarter's top line was driven by an 18% gain in hotel reservation revenue and a 33% jump in packaged-tour revenue. Profit, however, was hit by rapidly expanding costs -- namely, a 51% increase in product development costs, a 47% jump in sales and marketing expenses, and a 57% leap in general and administrative spending.

Now what: The market seems pretty pleased with Ctrip's quarter, but I'm not so sure that I'm on the same page. Top-line growth looks good -- and the company projected further 15% to 20% growth for all of 2012 -- but the growth in costs appears to be absolutely crushing profits. Since 2010, the company's operating margin has steadily fallen, from 36.6% that year, to 26.9% over the past 12 months. For this past quarter it was 19.4%.

Investors attracted by the company's strong growth may want to keep a keen eye on its expenses.

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