Active vs Passive Funds: The Trade-Off Explained

An active fund pays managers to pick securities in an attempt to beat a benchmark, while a passive (index) fund copies the benchmark and does not try to beat it. The trade-off is cost against the chance of outperformance: in 2025 investors in actively managed equity mutual funds paid an asset-weighted average of 0.64% a year, and investors in index equity mutual funds 0.05%, so the typical active dollar started about 0.59 percentage points behind before any stock was picked.

Key takeaways

The Investment Company Institute (ICI) reports 2025 asset-weighted average expense ratios of 0.64% for actively managed equity mutual funds and 0.05% for index equity mutual funds.
On an assumed 6% gross return, that gap compounds to about $8,700 less on a $10,000 investment after 30 years (illustrative, not a forecast).
In 2025, 79% of active large-cap U.S. equity funds trailed the S&P 500, but the share was lower for mid-caps (about 55%) and small-caps (about 41%), so the answer depends on the category and the year.
Funds that trade more tend to realize more capital gains when their holdings have risen in value, and the distributions are taxable in a taxable account even when reinvested; the effect is a tendency, not a rule for every fund.
The expense ratio is not the whole cost: trading costs inside the fund and brokerage or sales charges sit outside it.

What each fund type tries to do

An index fund aims to replicate the return of a specified index. According to the ICI, it generally holds all of the securities in its target index, or a representative sample of them, and its managers buy and hold rather than change positions often (ICI Fact Book 2026, chapter 6). Its best possible outcome is the index return minus its costs.

An active fund gives managers discretion to overweight or underweight sectors or securities, and to depart from the index in other ways, in pursuit of a better result. The same ICI chapter notes that active managers may also do their own research on stocks, bonds, market sectors or geographic regions. The benchmark is the yardstick for judging that effort, and the fund can end up either ahead of it or behind it.

Both types exist as mutual funds and as exchange-traded funds (ETFs). The ICI's fee tables report separate averages for actively managed and index versions of each, so "passive" describes a strategy, not a wrapper.

Cost: what the ICI averages show

A fund's expense ratio is its total annual operating expenses expressed as a percentage of its average net assets, and it is deducted from fund assets rather than billed to you (SEC Investor Bulletin on mutual fund and ETF fees). The ICI weights the expense ratio of each fund share class by its year-end assets, so its averages describe what the typical dollar invested paid, not what the typical fund charges. The difference is large: the ICI puts the 2025 simple average for all equity mutual funds at 1.09% and the asset-weighted average at 0.40%, because investors hold most of their money in lower-cost funds.

Fund category (2025, asset-weighted)	Actively managed	Index	Gap
Equity mutual funds	0.64%	0.05%	0.59 points
Bond mutual funds	0.44%	0.05%	0.39 points

Source: ICI Fact Book 2026, chapter 6, Figure 6.4. The data exclude mutual funds sold as investment choices in variable annuities. For ETFs, the ICI puts the 2025 average for index equity ETFs at 0.14%, and its March 2026 release gives 0.40% for all equity mutual funds combined, active and index together.

Two cautions apply. First, an average hides a wide range, so an individual active fund can cost much less than 0.64% and an individual index fund much more than 0.05%; the fee table in each fund's prospectus is the number that counts.

Second, the SEC points out that the expense ratio leaves out some costs: the trading costs a fund pays when it buys and sells securities, securities-lending costs, sales loads and brokerage commissions. A fund that trades more pays more of the first kind of cost without it appearing in the ratio.

A worked cost example

Illustrative example. Assume $10,000 invested in each of two equity funds that earn the same 6% a year before costs. This is an assumption chosen for round numbers, not a forecast. Fund A is active and charges 0.64%; Fund B is an index fund and charges 0.05% (the 2025 ICI averages). To keep the arithmetic simple, the net return is treated as the gross return minus the expense ratio.

Ending value = Start × (1 + gross return − expense ratio) ^ years

Fund A: $10,000 × (1 + 0.06 − 0.0064) ^ 30 = $47,893
Fund B: $10,000 × (1 + 0.06 − 0.0005) ^ 30 = $56,628

In the formula, "start" is the amount invested once, "gross return" is the return before fund costs, and "years" is the holding period. No contributions or taxes are included.

Years	Fund A (0.64%)	Fund B (0.05%)	Difference	Difference as % of Fund B
10	$16,856	$17,824	$968	5.4%
20	$28,413	$31,770	$3,357	10.6%
30	$47,893	$56,628	$8,735	15.4%

The lesson is a break-even bar, not a verdict. For the active fund to merely tie the index fund, its manager must earn about 0.59 percentage points a year more than the index before costs, on average over the holding period, and more than that if the active fund's trading costs, which sit outside the expense ratio, are higher. The gap is modest in any single year, and it grows with time because each year's smaller balance also compounds. Whether a particular manager clears that bar is the question the next sections address.

Taxes and turnover

Turnover is how much of a fund's portfolio is replaced in a year. When a fund sells a holding for more than it paid, it realizes a capital gain, and the SEC explains that in a taxable account, such as a brokerage account, you might owe tax on a fund's capital-gain, interest and dividend distributions, even if you reinvest them (SEC Investor Bulletin on fund distributions). A capital-gain distribution comes from the fund's sales, not yours, so it can be taxable in a year in which you sold nothing.

This is where the strategies differ in tendency. The ICI notes that index funds' portfolios tend not to change frequently and so have low turnover rates. A fund whose manager changes positions often has more chances to realize gains when its holdings have risen in value, and more of them reach shareholders as distributions; in a falling market, the same selling can realize losses instead. The pattern is not guaranteed: a patient active fund may distribute little, and an index fund can still pass on gains, for example when it must sell holdings to meet withdrawals or after a change in its index.

Only taxable accounts are affected in the way the SEC describes. If the fund sits in a tax-advantaged retirement account, the account type, not the fund's distributions, determines when tax is due; check the account's rules before treating tax efficiency as a deciding factor.

How often active funds win

The standard scorecard is S&P Dow Jones Indices' SPIVA (S&P Indices Versus Active) U.S. Scorecard. Its year-end 2025 edition found that 79% of all active large-cap U.S. equity funds underperformed the S&P 500 in 2025, up from 65% in 2024, and S&P described it as the fourth-worst year for active large-cap managers in the scorecard's 25-year history (S&P Dow Jones Indices, SPIVA U.S. Year-End 2025; the figure is also reported by InvestmentNews, March 4, 2026).

That is a single calendar year, and it moves a lot: the same scorecard showed 65% a year earlier. InvestmentNews reported that about 55% of mid-cap funds and 41% of small-cap funds trailed their benchmarks in 2025, so even in a poor year for large-cap managers, the share was lower elsewhere. The scorecard also reports results over longer periods than one year, which smooth out a single unusual year. The share of funds that trail is a count of funds, not a measure of how far they trail, and it says nothing about which funds will lead next year; that question of whether winners repeat is a separate topic.

Where active management is common

The ICI's explanation of why index funds cost less also shows where active funds concentrate. Net assets of index equity mutual funds are concentrated more heavily in large-cap blend funds that track US large-cap indexes such as the S&P 500, while net assets of actively managed equity mutual funds are spread more widely across stocks of varying capitalizations, international regions or specialized business sectors. The ICI adds that these areas are generally acknowledged to cost more to manage; elsewhere in the same chapter it explains that small- and mid-cap portfolios tend to cost more because information about those stocks is less readily available, so managers may need to spend more time on research.

That helps explain the fee gap, but it should not be read into the 2025 SPIVA counts. S&P noted that the S&P 500 beat the S&P MidCap 400 by 10% and the S&P SmallCap 600 by 12% in 2025, which gave mid- and small-cap managers room to gain ground by holding larger stocks than their benchmarks (SPIVA U.S. Year-End 2025). The lower share of small-cap funds trailing (41%, against 79% for large-cap funds) may therefore reflect that year's market rather than stock-picking skill, and it is not evidence that smaller segments are easier to beat.

Frequently asked questions

Can an index fund beat its own index?

By design it aims to match the index, not exceed it. Because the fund pays an expense ratio and the index itself carries no such charge, its return typically lands slightly below the index, and by roughly its costs. Small differences can also come from holding a representative sample rather than every security, which the ICI says some index funds do.

Does the cost gap exist in bond funds too?

Yes. The ICI's 2025 asset-weighted averages are 0.44% for actively managed bond mutual funds and 0.05% for index bond mutual funds. The gap in points is smaller than in equities (0.39 against 0.59), but the index funds' cost is the same 0.05%.

Is the expense ratio the only cost of owning a fund?

No. The SEC says the ratio does not include sales loads, brokerage commissions or other fees paid directly by the investor. It also leaves out some indirect costs, such as securities-lending costs and the transaction costs a fund pays when it buys and sells securities. These can reduce the value of an investment even though they are absent from the ratio.

Are all ETFs index funds?

No. The ICI describes ETFs as largely index-based, not entirely: actively managed ETFs registered under the Investment Company Act of 1940 held 11.1% of ETF total net assets at year-end 2025. Their 2025 asset-weighted average expense ratio was 0.44% for actively managed equity ETFs, against 0.14% for index equity ETFs. Check the fund's prospectus to see whether it tracks an index or relies on manager discretion.

Why does a fund's price fall when it pays a distribution?

The SEC explains that when a fund distributes dividends, interest or capital gains, its net asset value (NAV) decreases, and for exchange-traded funds the market price typically falls as well. This does not mean the investor lost money: the decrease reflects a transfer of value to the shareholder, in cash or in new shares. In a taxable account, though, that distribution may itself be taxable, even if it is reinvested.

A checklist before choosing

Find the expense ratio in the prospectus fee table and compare it with the category averages above; a single fund's number, not the average, is what you pay.
Check the fund's stated benchmark and decide whether the fund is built to copy it or to depart from it.
Look for portfolio turnover in the prospectus or annual report, and ask whether the account is taxable before weighing tax efficiency.
Work out the break-even gap: the fund's expense ratio minus the index fund's, then ask whether the strategy can plausibly beat its benchmark by at least that margin, on average, after its trading costs.
Run both costs through an investment growth calculator with your own contribution and horizon to see the dollar difference.