natural gas

Marathon, founded as the Ohio Oil Company, has gone through several incarnations over the decades. For a while it was taken over by the Standard Oil Trust, later it was acquired by U.S. Steel, and still later its refining and marketing operations were for a time part of a joint venture with Ashland Oil. Today Marathon is independent and is among the mid-sized oil majors based in the United States. The company has faced controversy in connection with the air pollution caused by its U.S.

ExxonMobil (NYSE: XOM) is the largest publicly traded integrated petroleum and natural gas company in the world, and the world's largest company measured by revenues ($404.5 billion in 2007) and market capitalization ($517.92 billion on July 20, 2007).

Noble Energy is an independent oil and gas exploration and production company with operations in the western United States, the Gulf of Mexico, the Middle East, the North Sea and West Africa. Some of its most significant (and most controversial) activity is off the coast of Equatorial Guinea, whose dictator Teodoro Obiang has been accused of using little of the revenue from foreign energy companies to help his own people.