Marathon shares surged in pre-market trading, rising 11 percent, or $4.47, to $45.
The refining company will be known as Marathon Petroleum Corp. and will be based in Findlay, Ohio. It's expected to be the nation's fifth-largest refiner with refineries in the Midwest, Gulf Coast and Southeast.
Marathon Petroleum will trade on the New York Stock Exchange under the symbol "MPC" starting on July 1. Marathon Oil Corp. will maintain the company's exploration and production assets as well as a business that produces oil from oil sands in Alberta, Canada. .
The exploration and production business had revenue of $2.53 billion in the third quarter, about one-sixth that of the refining and marketing business. The exploration division received an average of about $76 for each barrel of oil it sold and had an operating profit of $510 million.
But high oil prices make it harder for the refining business to make money. Marathon earned $285 million from refining and marketing in the quarter, about 44 percent less than it did from exploration.
Marathon reported net income of $696 million, or 98 cents per share, in the quarter compared with $413 million, or 58 cents per share a year earlier. .