Freeport-McMoRan Copper & Gold Inc. agreed on December 5 to acquire Plains Exploration & Production Company and McMoRan Exploration Co. for a total of $8.9 billion in cash and stock. Freeport-McMoRan will also assume $11 billion in debt in the two deals.

Freeport-McMoRan will pay $6.8 billion for Plains, half in cash and half in stock. At $50 per Plains share, the deal came at a 39 percent premium to the target’s closing price on December 4. Plains has aggressively snapped up oil and gas properties in recent years and last fall paid BP p.l.c. $5.55 billion for oil and gas assets in the Gulf of Mexico [ Big Deals, January].