On September 28, 1916, John D. Rockefeller Sr. became world’s first $1 billion billionaire, five years after the Supreme Court ordered the breakup of Standard Oil. The Sherman Antitrust Act aimed to curb monopoly power, yet it failed to stem Rockefeller’s fortune. While courts wrestled with corporate dominance, a new view of equity was taking shape, setting the stage for unprecedented wealth and for future capital markets.

Investors in the 1880s and 1890s argued over a share’s meaning. Henry Poor and Wall Street Journal editors insisted a stock must reflect a company’s physical assets, a stance Theodore Roosevelt echoed in 1901 urging U.S. Steel shares to represent plant value. Financiers Jay Gould, J.P. Morgan and Rockefeller broke that link, treating shares as abstract claims untethered from tangible property.

That abstract conception birthed the modern equity market, enabling rapid capital accumulation and the rise of mega‑wealth. The mechanism that vaulted Rockefeller to billionaire status now fuels Elon Musk’s ascent as the world’s first trillionaire. Tracing back to railroads—the era’s first massive enterprises—shows how a shift in valuation logic reshaped capital formation for today’s investors.