Vanguard 500 Index Fund is marking its 50th anniversary after launching as First Index Investment Trust on August 31, 1976. Created by Vanguard Founder John C. Bogle, the first publicly available mutual fund tracking the S&P 500 Index gave investors a low-cost way to own a broad cross-section of the U.S. stock market. The fund raised $11.3 million at launch, compared with a $150 million target, as investors initially questioned whether broad-market indexing could compete with active strategies. All classes of the Vanguard 500 Index Fund now hold $1.67 trillion in assets, according to Morningstar. The Investment Company Institute said index mutual funds and exchange-traded funds hold 50% more assets than actively managed U.S. stock funds. Vanguard says a hypothetical $10,000 investment at launch grew to more than $2.4 million by July 31, 2026, while index investing helped investors save approximately $570 billion in fees since 2000. Index funds later became foundational holdings in 401(k) plans and other retirement portfolios because of their low costs, diversification, ease of maintenance and tax efficiency. Lower portfolio turnover can reduce capital-gains events and help retirees manage taxable income, Social Security taxation and potential Medicare premium surcharges.