Marathon Oil says it will spin off its refining and marketing business, leaving it with its operations that search for and produce oil and gas.

The company says the move will allow it to be more flexible in operational decisions.

Its shares climbed $4.83, or 11.9 percent, to $45.36 in pre-market trading.

The Houston oil company said Thursday that 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 property mainly in the Midwest, Gulf Coast and Southeast.

The spin-off is expected to be completed on June 30. Marathon Petroleum will trade on the New York Stock Exchange under the symbol "MPC."

Marathon Oil Corp. will maintain the company's exploration and production assets.