Rockefeller saw the cutthroat competition in the oil industry as a ruinous influence and began to methodically stamp it out. Under his firm hand, and due to his seemingly super-human abilities to choose excellent managers, by 1890 Rockefeller's company, Standard Oil of Ohio, was well ahead of the industry and enjoying a high profit margin. He used these profits to buy out competitors. If a competitor did not want to be bought out, Rockefeller had his means of persuasion.
Read more: J.D. Rockefeller: From Oil Baron To Billionaire http://www.investopedia.com/articles/economics/08/jd-rockefeller.asp#ixzz3uKHilzHN
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