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 offshore support specialist SEACOR Holdings (NYSE: CKH) are taking a beating today, falling 12.5% at the time of this writing in a continued downward trend on heavy volume.

So what: SEACOR's fourth-quarter earnings got roughed up by the drop in drilling activity that followed last year's Gulf of Mexico oil spill.

Now what: If that weren't bad enough for SEACOR, cleanup activity around the spill is dropping off quicker than interest in American Idol. SEACOR is stuck with a growing fleet of vessels sitting unused, daily service rates are dropping precipitously, and there's really nothing good going on here. Curiously, direct competitors Gulfmark Offshore (NYSE: GLF) and Tidewater (NYSE: TDW) were not hurt by this detailed account of slow Gulf business, making me wonder if those stocks are getting set up for their own pullbacks on their next earnings reports. That said, fellow Fool Jason Moser has put real money into both of the SEACOR rivals; click those links to get his views.

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Fool contributor Anders Bylund holds no position in any of the companies discussed here. The Fool owns shares of Gulfmark Offshore and Tidewater. 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 is investors writing for investors.