Most people start investing with funds rather than individual stocks, and for good reason: a single fund buys you diversification, and it is simple to own and track. Funds come in two basic flavors, and the choice between them matters more than almost any other decision a beginning investor makes.

  • Actively managed funds employ a manager or team to pick the stocks and bonds inside the fund and trade them in an attempt to beat the market.
  • Index funds are passively managed. Nobody is picking; the fund simply holds what is in a benchmark such as the S&P 500, in the same proportions, and its return tracks the index minus a small fee.

A short history

Before 1976, essentially every fund was actively managed. On August 31 of that year, John Bogle’s Vanguard launched the First Index Investment Trust, now the Vanguard 500 Index Fund. The offering raised about $11 million and the fund charged 0.43% a year. Fifty years later the same fund’s admiral shares charge 0.04% and its ETF twin 0.03%, and by year-end 2025 index equity funds with expense ratios in the cheapest quartile held 85% of all index equity mutual fund assets, according to the Investment Company Institute. The experiment became the default.

Why index funds usually win: cost

An active manager has to be paid, and the fee comes out of your return every year whether or not the manager beats the market. The Investment Company Institute’s 2026 Fact Book puts the asset-weighted average expense ratio at 0.64% for actively managed equity mutual funds in 2025, against 0.05% for index equity mutual funds; active bond funds averaged 0.44% versus 0.05% for index bond funds. Active funds have gotten cheaper (the equity average was 1.06% in 2000), but the gap has barely narrowed because index funds got cheaper faster.

A gap of 0.59 percentage points sounds small. Compounded, it is not. On a $100,000 portfolio it is $590 a year before any growth. Assume the market delivers roughly 10% a year before fees, the long-run compounded average for the S&P 500 since 1928 in NYU Stern professor Aswath Damodaran’s data, and run both funds for 30 years: the 0.05% fund grows to about $1.72 million and the 0.64% fund to about $1.46 million. The manager’s fee cost roughly a quarter of a million dollars, and that is before any underperformance.

Why index funds usually win: performance

The fee would be worth paying if managers reliably beat the market after costs. Most do not. S&P Dow Jones Indices’ SPIVA scorecard, which has tracked this for more than two decades, found that as of June 30, 2025, 72.61% of large-cap U.S. funds trailed the S&P 500 over the prior year, 86.91% over five years, 85.98% over ten and 91.03% over twenty. Adjust for risk and the 20-year figure rises to 96.17%. Only about a third of the large-cap funds that existed 20 years earlier were still around; the rest were closed or merged, usually after poor results. The pattern holds for mid-cap and small-cap funds, where roughly 88% trailed their benchmarks over 20 years.

The lesson is not that no manager ever wins. Some do, in some periods. The problem is identifying them in advance; past outperformance is a weak guide to future outperformance, and the fee is charged either way.

Mutual fund or ETF?

Both structures come in active and index versions. Exchange-traded funds trade during the day like stocks, usually have no investment minimum, and are typically the cheaper wrapper: index equity ETFs averaged 0.14% in 2025 and index bond ETFs 0.09%, per ICI. ETFs also tend to be more tax-efficient in a taxable account, because the way they create and redeem shares lets them avoid distributing capital gains to shareholders the way mutual funds often must. Inside an IRA or 401(k) the tax difference disappears, and the lowest-cost option your plan offers is usually the right one. Active ETFs exist too and have grown to about 11% of ETF assets, but an active ETF carries the same performance problem as an active mutual fund at a somewhat lower fee (0.44% for active equity ETFs in 2025).

When active management earns its keep

Three cases are defensible:

  • Corners of the market without a good index. Some bond niches, small foreign markets and specialized strategies are hard to index cheaply.
  • A fund you will actually hold. If a manager’s approach keeps you invested through a downturn when an index fund would have scared you out, the behavioral benefit can outweigh the fee.
  • Your 401(k) offers nothing else. Then pick the cheapest broad fund on the menu and ask the plan administrator for an index option.

If you do go active, compare expense ratios first, insist on a long track record under the same manager, and remember that the odds above are the base rate you are betting against.

The simple portfolio

For most investors, a low-cost total-market or S&P 500 index fund plus a broad bond index fund, rebalanced occasionally, has beaten the large majority of professionally managed alternatives over the past two decades. If even that is more tinkering than you want, a target-date fund bundles the index funds and the rebalancing into one holding; roughly six in ten participants in Vanguard-administered 401(k) plans already hold a single target-date or balanced fund, and our explainer on target-date funds covers how they work. Fund the accounts first, though: the 2026 contribution ceilings for 401(k)s and IRAs are in this year’s limits, and no fee decision matters as much as the amount you put in.