NEW YORK, July 7 — The figure that matters: $900 million. That was John D. Rockefeller’s personal fortune at its peak in 1913, a sum equivalent to roughly 2% of the entire U.S. economy at the time.
Adjusted for inflation, his net worth is estimated at over $400 billion, placing him among the richest individuals in history. The bottom line: Rockefeller built that wealth through Standard Oil, the company he founded in 1870 that by 1880 controlled about 90% of U.S. oil refining.
The company’s rise was neither gentle nor accidental. Rockefeller entered the oil business in 1863, building his first refinery near Cleveland, Ohio. From that single facility, he constructed a monopoly that would define American industry for decades.
The Monopoly Machine
Standard Oil’s tactics were aggressive and, by modern standards, ruthless. The company secured secret railroad rebates — discounted shipping rates unavailable to competitors — and used predatory pricing, deliberately selling below cost in local markets to drive rivals out of business. These practices drew the attention of federal regulators and ultimately the U.S. Supreme Court.
In 1911, the Court ruled that Standard Oil was an illegal monopoly under the Sherman Antitrust Act of 1890. The decision ordered the breakup of the company into 34 separate entities.
Investors will note that many of those successor companies — including Exxon, Mobil, Chevron, and Amoco — went on to become giants in their own right. Rockefeller was born in Richford, New York, on July 8, 1839. He lived to age 97, dying in 1937.
By the numbers, his life spanned from the presidency of Martin Van Buren to the Great Depression.
The Philanthropic Turn
In later life, Rockefeller became a major philanthropist, donating over $500 million to various causes. The University of Chicago, founded in 1890, was established with his support. The Rockefeller Institute for Medical Research — now Rockefeller University — was founded in 1901.
And the Rockefeller Foundation, perhaps his most enduring institutional legacy, was established in 1913. The figure that matters for his philanthropic work: half a billion dollars, donated in an era when that sum represented extraordinary wealth.
The institutions he funded remain operational today, conducting research and educating students more than a century after their founding. Rockefeller’s story presents a paradox that business historians continue to debate. He built a monopoly through tactics the Supreme Court deemed illegal, yet he gave away a fortune that funded scientific and educational institutions of lasting value.
The Sherman Antitrust Act, which brought down Standard Oil, remains a cornerstone of U.S. competition law. What to watch next: The 34 companies that emerged from Standard Oil’s breakup have undergone their own mergers and acquisitions over the past century.
The descendants of those companies — ExxonMobil, Chevron, and others — remain among the world’s largest oil producers. The legal framework that broke up Rockefeller’s monopoly continues to shape antitrust enforcement today, as regulators examine the market power of technology companies and other modern industries.
