Standard Oil Standard Oil Standard Oil Co. Inc. was an American oil producing, transporting, refining, and marketing company. Established in 1870 by John D. Rockefeller and Henry Flagler as a corporation in Ohio, it was the largest oil refinery in the world of its time. Its history as one of the world's first and largest multinational corporations ended in 1911, when the United States Supreme Court, in a landmark case, ruled that Standard Oil was an illegal monopoly. Standard Oil dominated the oil products market initially through horizontal integration in the refining sector, then, in later years vertical integration; the company was
Standard Oil most of them remained together. The only company since the breakup of Standard Oil that was divided into parts like Standard Oil was AT&T, which after decades as a regulated natural monopoly, was forced to divest itself of the Bell System in 1984. The successor companies from Standard Oil's breakup form the core of today's US oil industry. (Several of these companies were considered among the Seven Sisters who dominated the industry worldwide for much of the 20th century.) They include: Other Standard Oil spin-offs: Other companies divested in the 1911 breakup: Note: Standard Oil of Colorado was not a