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 crude oil shipper General Maritime (NYSE: GMR) were hammered today, falling as much as 30% on heavier-than-average volume.

So what: General Maritime told investors yesterday that it wouldn't end up filing its annual 10-K report until closer to the end of the month. It was the reason for the delay that has investors spooked. In its filing with the SEC, the company basically said "We've been so busy dealing with our debt and talking with lenders about a possible restructuring and refinancing that we haven't had time to get to the 10-K yet." And that's not the kind of talk investors like to hear.

Now what: General Maritime did provide investors with some preliminary financial information for the fourth quarter, so they'll have some idea of what to expect when full results are reported. Unfortunately, the results don't look so hot. Revenue was down 15% from the prior year and was short of what analysts were looking for. On the bottom line, it's expected that the net loss expanded significantly from last year, even before considering a $100 million writedown on its vessels. Of course, while investors are no doubt interested in what happened in the fourth quarter, the bigger concern now is the outcome of General Maritime's discussions with its lenders.

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Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or on his RSS feed. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.