Marathon Petroleum Corporation is an American petroleum refining, marketing, and transportation company headquartered in Findlay, Ohio. The company was a wholly owned subsidiary of Marathon Oil until a corporate spin-off in 2011.\nFollowing its acquisition of Andeavor on October 1, 2018, Marathon Petroleum became the largest petroleum refinery operator in the United States, with 16 refineries and over 3 million barrels per day of refining capacity. Marathon Petroleum ranked No. 41 on the 2018 Fortune 500 list of the largest United States corporations by total revenue.