Billionaire activist investor Carl Icahn acquired a 1.56 percent stake in Transocean Ltd, the Swiss offshore rig contractors, and is eyeing an additional share in the company.

In a statement on Transocean's website, Icahn notified the company that he's seeking regulatory approval to acquire shares worth more than $682.1 million. Once approved, Icahn would become one of Transocean's largest shareholders with just over 5 percent of the company, based on its closing stock price of $54.09 on Jan. 11, Reuters reported.

Icahn has already acquired huge stakes in energy companies such as Oklahoma City-based natural gas producer Chesapeake Energy Corp. and Sugar Land, Texas- based oil refiner CVR Energy Inc. He's known to invest in those companies, which he considers to be underperforming and then pushing for change, reported  Bloomberg Businessweek.

The move came 10 days after Transocean said it had agreed to pay a $1.4 billion fine for its role in the worst U.S. maritime oil spill in the Gulf of Mexico in 2010. As per the Bloomberg Businessweek reports, the company's shares fell and it lost more than half its value following the oil spill, they remain 41 percent below their pre-spill price.

Capital World Investors, a division of The Capital Group Companies Inc, is Transocean's biggest shareholder. It owned 5.12 percent shares as of Oct 15, according to Thomson Reuters data.

Transocean shares rose majorly in 28 months after the settlement was announced Jan. 3, hinting at rising investor demand, reported Bloomberg Businessweek. It further reported that the offshore rig contractor has continued to rule the Gulf of Mexico's deep-water drilling market. Transocean owns 14 of the 37 rigs, which are actively drilling in Gulf water depths of at least 1,000 feet (305 meters), more than any other operator, according to global offshore rig data tracker Dice Holdings Inc. Rigzone.