Odyssey Marine fights for its $500 milllion deep sea booty

Odyssey Marine Exploration Inc. (OMEX), which shrouds its for-profit underwater archaeological digs in secrecy, suffered a very public setback today after a federal magistrate ruled that contents from a ship wreck codenamed "Black Swan," whose 2007 discovery was greeted by an avalanche of publicity, are the property of the government of Spain.

Shares of the Tampa, Florida-based company plunged nearly 43 percent in mid-afternoon trading, erasing its gains for the year. Earlier, Odyssey shares hit $1.39, which Bloomberg News said was their lowest level since July 2003. The value of the Black Swan's treasure of 500,000 coins weighing more than 17 tons, has been estimated at $500 million