?Hedge-fund billionaire George Soros has acquired a 6% interest in Houston E&P Plains Exploration & Production Co. (NYSE: PXP). A 13G filing with the SEC revealed Soros’ fund Soros Fund Management gained 6,467,400 shares of Plains on April 21.

Soros, one of the world’s richest men and known for his investing acumen and political activism, came out of retirement in 2007 at the age of 77 to retake the helm of his hedge fund in the face of troubled financial markets. Plains holds 110,000 net nonoperated acres in the Haynesville shale play in northern Louisiana in a joint venture with Chesapeake Energy Corp., Oklahoma City (NYSE: CHK).