Mutual Funds
Mutual funds let thousands of people chip in together and hire a professional to invest on their behalf.
By Greg Goodwin · Published October 16, 2026 · Updated October 24, 2026
Cheat Sheet
- What it is: a pooled investment that holds a portfolio of securities, managed by a professional or designed to track an index.
- Pricing: shares are bought and sold at net asset value (NAV), calculated once per day after the market closes.
- First US mutual fund: the Massachusetts Investors Trust, launched in 1924.
- Index pioneer: John Bogle's First Index Investment Trust (1976), later Vanguard's 500 Index Fund.
- Regulation: in the US, governed mainly by the Investment Company Act of 1940.
- Where you meet them: mutual funds dominate 401(k) and many other workplace retirement plans.
The 60-Second Version
A mutual fund collects money from many investors and uses it to buy a diversified portfolio of stocks, bonds, or other assets. Each investor owns shares in the fund and shares in its gains, losses, and income. The price per share, the NAV, is calculated once a day after markets close. Some funds are actively managed, with managers choosing investments to try to beat a benchmark, while index funds simply follow a market index and charge less. Fees matter because they compound over decades. Mutual funds are the backbone of many retirement plans. This is general education, not personalized investment advice.
The Long Version
How They Work
When you invest, you buy shares directly from the fund company at the day's NAV, and when you sell, the fund redeems them at that day's NAV. The fund's board and manager oversee the portfolio, and an independent custodian holds the assets. Because the fund is regulated as an investment company, it must provide a prospectus describing objectives, fees, and risks, and report holdings regularly. A single fund might hold hundreds of securities, giving small investors diversification that would be expensive to build alone.
A Short History
The idea of pooled investing dates back to 18th-century Dutch trusts, but the modern US industry began with the Massachusetts Investors Trust in 1924. After the 1929 crash, the Investment Company Act of 1940 set rules to protect investors. In 1976, John Bogle launched the first retail index fund, arguing that most managers fail to beat the market after costs, a claim that was initially mocked as "Bogle's folly." Mutual funds exploded in the 1980s and 1990s with the growth of 401(k) plans.
Types of Funds
Equity funds invest in stocks and may focus on large companies, small companies, growth, value, or international markets. Bond funds hold government or corporate debt. Balanced funds mix the two. Money market funds invest in short-term, high-quality debt and aim to keep a stable value, though they are not guaranteed. Target-date funds adjust their mix over time and are common default options in retirement plans.
Costs and Performance
Costs include the expense ratio and, for some share classes, sales loads or 12b-1 marketing fees. Index funds often cost under 0.2 percent per year, while actively managed funds may cost 0.5 to 1 percent or more. Research, including the S&P's regular SPIVA reports, has found that over long periods the majority of actively managed US stock funds underperform their benchmarks after fees, though some beat the market in some years. Past performance does not guarantee future results.
Taxes and ETFs
In taxable accounts, mutual funds can distribute capital gains when managers sell holdings, even if you did not sell any shares yourself. Holding funds in tax-advantaged accounts such as IRAs and 401(k)s avoids that issue. ETFs offer a similar pooled approach but trade like stocks and often distribute fewer gains. Which is better depends on the investor's situation, including account type, trading habits, and costs, and a licensed advisor can help.
Why People Care
Mutual funds are how millions of people invest for retirement, often without realizing it. Knowing how fees, taxes, and management style affect long-term results can make a big difference in the outcome.
Glossary
- Net asset value (NAV)
- A fund's total assets minus liabilities, divided by shares outstanding.
- Load
- A sales charge paid when buying or selling shares of some funds.
- Expense ratio
- The annual percentage of assets deducted to pay a fund's operating costs.
- Target-date fund
- A fund that automatically shifts from stocks toward bonds as a chosen retirement year approaches.
- Capital gains distribution
- A payout of profits the fund realized from selling holdings, which can be taxable.
Go Deeper
More to Explore
- Compound Interest
Compound interest is what happens when your money gets a job and then hires its own employees.
- Exchange-Traded Funds (ETFs)
An ETF lets you buy hundreds of companies with one click, the same way you would buy a single share.
- Options Trading Basics
Buying an option risks only what you paid for it, while selling one can cost far more, the big asymmetry of options.
- Dividend Investing
A sky-high dividend yield can be a warning sign rather than a bargain: sometimes the share price has simply been falling.
- Bonds
When interest rates rise, the bonds you already own lose value, because bond prices and rates move in opposite directions.