ANTITRUST REGULATION During the late nineteenth century, John D. Rockefeller Sr., considered the richest businessman in the world, controlled more than 90 percent of the U.S. oil refining business. But antitrust regulations were used in 1911 to bust up Rockefeller’s powerful Standard Oil into more than thirty separate companies. He later hired PR guru Ivy Lee to refashion his negative image as a greedy corporate mogul.