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: One day after World Fuel Services (NYSE: INT) reported a 35% increase in Q2 profit, its stock reacted -- up 11% in Wednesday trading.

So what: That's a pretty big number on the earnings side, but it pales in comparison with WFS's top-line performance, where revenues nearly doubled to $8.7 billion at the fuel logistics company.

Now what: Sound good? Not so fast -- it wasn't uniformly great news. If WFS's GAAP numbers are going vertical, we're seeing a different trajectory entirely on the cash-flow statement. Free cash flow in Q2 was nearly cut in half from last year's Q2 number. So far this year, the company has managed to burn through about $145 million in cash -- quite a turnaround from the near-$20 million it generated in last year's first half.

Long story short, even at 17 times earnings, this stock is no bargain.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.