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: You might think investors would be happy to hear Wabash National (NYSE: WNC) announce earnings of $0.05 per share yesterday, instead of the $4.64 per share it lost last year. You might think they'd be especially pleased by the earnings number considering analysts had told them to expect only $0.02 per share in profits. And that they'd be thrilled to learn from CEO Dick Giromini that Wabash just booked its biggest first-quarter gross profit margin since 2007. You might think all that … but you'd be wrong.

Instead of cheering and tickertape, investors met Wabash's news with a wave of catcalls, and a 10% drop in share price.

So what: Maybe investors were just too optimistic, and assumed Wabash would beat bigger than it actually did. After all, aside from a few outliers like YRC Worldwide (Nasdaq: YRCW), we've seen generally strong results from truckers Old Dominion Freight (Nasdaq: ODFL), JB Hunt (Nasdaq: JBHT), and UPS (NYSE: UPS) these past few weeks. And Wabash does build trailers for trucking fleets. Success this past quarter may have been a conclusion foregone -- and optimism, overblown.

Now what: Now that reality has set in, what we're left with at Wabash is a company that's barely breaking even on a GAAP basis, and still burning cash like a trucker burns diesel. Until it gets its cashflow fixed, I wouldn't recommend hitching a ride.

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The Fool owns shares of UPS, but Fool contributor Rich Smith does not own shares of, nor is he short, any company named above.  The Motley Fool has a disclosure policy. Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.