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 Great Lakes Dredge & Dock (NASDAQ:GLDD) fell 18% today after the company said it would have to restate earnings.

So what: The company actually reported fourth quarter earnings, which included revenue of $207.1 million and net income of $0.3 million. But the bigger news was that it discovered revenue that wasn't correctly reported during 2012, so it will be restating second and third quarter results.

Now what: The impact isn't huge, just an overstatement of $3.9 million in revenue in the second quarter, and $4.3 million in the third quarter, but it's the principle that counts. Investors hate restatements, and they give us less confidence in what the company is reporting. I wouldn't worry about this too much because it was caught quickly, and I think shares can recover from here.

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Fool contributor Travis Hoium has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.