The United States at 250: A Nation of Investors
The United States didn’t transform into a nation of investors overnight. It took the thrift, innovation, and prudence of generations of Americans as well as the right institutions, products, and policies to make capital ownership a key feature of middle-class American life. More than half the country—76 million US households—embrace those hallmarks today by investing in US investment companies like mutual funds or exchange-traded funds (ETFs). These roughly 130 million individual investors hold a direct stake in the success of American businesses.
The Birth of Pooled Investing
The idea behind modern funds is simple: investors pool their money to gain access to professionally managed, diversified portfolios. A Dutch merchant pioneered pooled investing in the late 1700s, and British investment trusts brought the model closer to American shores in the 1800s. The Scottish American Investment Trust, formed in 1873 by Robert Fleming, channeled British capital into US railroad bonds and the post–Civil War economy—planting the seeds of the modern fund model on this side of the Atlantic.
Massachusetts Investors Trust opened in Boston as the first US open-end mutual fund in 1924, offering ordinary investors what had long been reserved for the wealthy: professional management, diversification, and daily liquidity. The fund industry remained small through the Great Depression, but the Investment Company Act of 1940 established the regulatory framework that would underpin every dollar invested in regulated funds for the next 85 years.
Effective New Policies
Three major developments in the 1970s and 1980s fostered direct participation in financial markets by individual investors.
The Employee Retirement Income Security Act of 1974 created the traditional individual retirement account (IRA) to provide a contributory retirement savings vehicle—originally for individuals not covered by retirement plans at work—and as a place to roll over accumulations from employer-sponsored retirement plans. Today, IRAs are one of the most important channels for moving household retirement savings into financial markets, with IRAs growing to more than $18 trillion (Figure 1).
Figure 1
IRAs Help Channel Savings Into Market Investments
Note: IRAs include traditional, Roth, and employer-sponsored IRAs.
Sources: Investment Company Institute, IRS Statistics of Income, American Council of Life Insurers, and Federal Reserve Board; see Investment Company Institute, Quarterly Retirement Market Update
That same decade, with inflation rising and federal interest-rate ceilings limiting what banks could pay on deposits, money market funds emerged, offering savers a higher-yielding alternative and introducing millions of households to the idea of pooled investing for the first time.
The Revenue Act of 1978 added a new provision to the tax code—Section 401(k)—and by the early 1980s, employers had begun building defined contribution plans around it. Within a generation, the 401(k) became the dominant retirement vehicle for American workers and the primary way many households participate in financial markets.
Together, these changes helped transform mutual funds from a relatively small corner of the financial system into a central tool for household investing. At the US bicentennial in 1976, mutual fund assets totaled $51.3 billion. Approaching the semiquincentennial, more than 120 million individual investors own mutual funds, and mutual fund assets have topped $32 trillion (Figure 2).
Figure 2
Mutual Fund Assets in the United States Top $32 Trillion
Total net assets; year-end, billions of dollars
* Data as of April 2026.
Sources: Investment Company Institute and 2025 Investment Company Institute Annual Mutual Fund Shareholder Tracking Survey
A Broader On-Ramp
The introduction of the ETF in the United States in 1993 widened access further. ETFs combined the diversification of a mutual fund with the trading flexibility of a stock. By the late 1990s, roughly half of US households owned equities directly or through funds—a threshold Americans have exceeded since.
Today, nearly six in 10 US households own stocks, whether directly or through mutual funds, ETFs, closed-end funds, collective investment trusts through 401(k) plans, or other pooled investment funds (Figure 3). And the role of mutual funds in expanding the investor base can be seen in the similar rise in mutual fund ownership over the past three decades.
Figure 3
Americans Are a Nation of Investors
Incidence; percentage of US households
*Stock holdings include direct holdings of shares as well as indirect holdings through mutual funds, ETFs, closed-end funds, collective investment trusts, and other pooled investment funds.
**Mutual funds include stock, balanced, bond, and money market funds.
Sources: Federal Reserve Board Survey of Consumer Finances (SCF) and Investment Company Institute Annual Mutual Fund Shareholder Tracking Survey
Today, US investment companies manage more than $47 trillion in assets and hold one-third of US corporate equities, about one-quarter of corporate bonds, and 29% of municipal securities outstanding. Funds channel this capital into factories in the Midwest, hospitals in the South, and schools and bridges across all 50 states. And mutual fund ownership has grown fastest over the past two decades among middle- and lower-income families, broadening the base of household participation in capital markets.
A Quarter-Millennium Stake
The democratization of American ownership did not come from any single law, product, or innovation. It came from decades of sound policy, product development, and household discipline: the framework of the 1940 Act, the savings vehicles created in the 1970s and 1980s, the innovation and competition that followed, and millions of steady decisions by Americans to invest in the productive economy.
As America marks 250 years, the US retirement system—now approaching $50 trillion in assets—has become one of the main ways Americans build long-term wealth and participate in capital markets. The nation that declared its independence in 1776 now has a majority of households with a personal stake in the success of American enterprise. That is to say, it has become a nation of investors.