Chevron (CVX) will buy Atlas Energy (ATN) for $3.2 billion cash and $1.1 billion of assumed net debt. Acquiring Atlas will give Chevron a greater presence in the Pennsylvania's Marcellus Shale natural-gas deposits.

"This acquisition is the right opportunity for Chevron," said George L. Kirkland, Chevron vice chairman. "We are acquiring a company that has one of the premier acreage positions in the prolific Marcellus."

Chevron will acquire Atlas Energy's estimated 9 trillion cubic feet of natural-gas resources. This includes about 850 billion cubic feet of proved natural-gas reserves and 80 million cubic feet of daily natural-gas production.

It is unclear when the deal, which is still subject to approval from Atlas Energy shareholders and regulators, will close.