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 oil driller Hercules Offshore (Nasdaq: HERO) were trading down as much as 14% in intraday trading on heavy volume.

So what: The story out of Hercules' corner today is anything but heroic. In an SEC filing yesterday, the company revealed that it is being investigated by the SEC and that the Department of Justice is also reviewing some of its activities. Hercules may have run afoul of the U.S.'s Foreign Corrupt Practices Act, which basically prevents companies from winning business abroad through bribes. The probe may be particularly notable considering the strength that Hercules has seen in its international division as business in the Gulf of Mexico has struggled.

Now what: Violations of the FCPA are hardly unheard of in the oil and gas industry. Just last November, Royal Dutch Shell (NYSE: RDS-A) -- along with drillers Transocean (NYSE: RIG), Noble (NYSE: NE), and Pride International (NYSE: PDE) -- was among a group of companies that paid fines and settlements in connection with alleged FCPA violations. The fines in those cases varied considerably in size; Noble paid a total of $8.2 million, while Pride doled out $56.2 million. It's notable that all three drillers mentioned above are substantially larger than Hercules.

After a massive run in Hercules' stock that has seen it roughly triple since last fall, the drop today shouldn't be all that painful for all but the most recent buyers of the stock. However, with the extent of the violations still unknown, investors will want to watch this very closely.

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Fool contributor Matt Koppenheffer does not have a financial interest in 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.