rockefeller was an entrepreneur of Standard Oil Trust and used vertical integration
John D. Rockefeller was the richest man in America in his time and one of the first major tycoons. He founded the Standard Oil Company
In 1865, Rockefeller borrowed money to buy out some of his partners and take control of the refinery, which had become the largest in Cleveland. Over the next few years, he acquired new partners and expanded his business interests in the growing oil industry.