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Cage Match: Traditional Index Funds vs. ETFs

How do they stack up when it comes to costs, trading capabilities, and taxes?


Editor’s Note: A version of this article appeared on Oct. 23, 2023.

Exchange-traded funds have garnered much of the buzz—and new assets—in the mutual fund industry over the past decade. In 2023, US investors poured $600 billion into ETFs, while traditional index funds received just a fraction of that amount. But at heart, ETFs aren’t a whole lot different from traditional index funds, which have been around since the 1970s. Most traditional index funds and ETFs track some type of benchmark, offering investors exposure to a market segment in a convenient package. Low costs and good tax efficiency are also hallmarks of many ETFs and index funds.

Yet there are small differences, too, when it comes to trading, tax efficiency, reinvesting dividends, and so on. In the end, the decision about whether to choose a traditional index fund or an ETF depends on the investor. Choosing between these product types boils down to what features the investor values most, where and how he or she is investing, his or her level of assets, and other key factors.

For this traditional index fund versus ETF cage match, I take a look at the following areas:

  • Expense ratios
  • Trading costs
  • Trading flexibility
  • Tax efficiency
  • Exposure to major market segments
  • Variations/strategic-beta opportunities
  • Ability to buy in with a low dollar amount
  • Ability to reinvest dividends and capital gains

Here’s a head-to-head comparison of ETFs versus traditional index mutual funds.

Expense Ratios: Tie

Exchange-traded funds initially garnered headlines as being cheaper than traditional index funds. But price wars have raged for nearly two decades, putting downward pressure on traditional index fund expense ratios. At this point, the two product types are closely aligned on the cost front. One major swing factor, however, is purchase size. Small investors might not qualify for the cheapest share class available for traditional index funds at firms like Vanguard and Fidelity, but low-cost ETF shares are available to investors regardless of purchase amount. However, if an ETF investor pays commissions to buy and sell—an increasingly rare scenario these days—that can erode the expense-ratio advantage of the ETF.

For investors with larger asset levels and long holding periods, ETFs and traditional index funds are fungible from an expense-ratio standpoint. However, Vanguard’s traditional index funds, which are large and managed at cost, put downward pressure on traditional index funds’ expense ratios on an asset-weighted basis. That makes traditional index funds’ asset-weighted expense ratios look lower than would be the case without the “Vanguard effect.” The “Vanguard effect” is also at work in the ETF space, though Vanguard has a smaller share of the ETF market than is the case in the traditional index fund space.

Trading Costs: Advantage Traditional Index Funds

In the early days of ETFs, investors had to pay commissions to buy and sell, whereas most traditional index funds were available on a no-load, commission-free basis. These days, however, most large brokerage platforms offer at least some ETFs on a commission-free basis, so this isn’t as great a disadvantage for ETFs as it once was. However, investors transacting in ETFs that aren’t on the brokerage firm’s “commission-free” list will still pay commissions to buy and sell.

Moreover, ETF investors can confront other transaction costs. ETFs may trade at small premiums and discounts to their underlying assets. Additionally, investors may confront bid-ask spreads and market-impact costs, particularly if they’re buying or selling large amounts in ETFs with low liquidity or that hold less liquid holdings. Trading costs won’t matter much to ETF investors who are trading little, sticking exclusively to their brokerage firm or mutual fund company’s commission-free lineup, and focusing on highly liquid ETFs with liquid holdings, but they can be more meaningful to investors who do otherwise. (Frequent traders of traditional index mutual funds might also face redemption fees, however.)

Trading Flexibility: Advantage ETFs

One of the major differentiators between traditional index mutual funds and ETFs is the ability to trade ETFs intraday. Traditional mutual funds—index or otherwise—can only be purchased once a day, after the market is closed and the current value of the securities in the portfolio is toted up. Investors also have the ability to customize their order type with ETFs, using limit orders, stop-loss orders, and stop-limit orders. Buy-and-hold investors have no reason to value these features or the ability to trade intraday, but investors who trade frequently will find that ETFs give them more flexibility.

Tax Efficiency: Advantage ETFs

Plain-vanilla, market-cap-weighted equity index funds—whether the traditional variety or ETFs—are pretty tax-efficient vehicles (with the exception of bond index funds.) Their big tax-efficiency advantage comes from their low turnover: Trading infrequently means they rarely realize and distribute capital gains to their shareholders, making them fine holdings for investors’ taxable accounts.

Yet equity ETFs have a slight edge on the tax-efficiency front versus their traditional index fund counterparts. That’s because investors in traditional index funds can redeem their shares at any time, which forces the manager to raise cash to pay off departing shareholders; that may force the selling of securities that have appreciated, unlocking capital gains. Investors in exchange-traded funds, by contrast, mostly trade with one another in the secondary market; that buying and selling doesn’t affect the holdings in an index. For larger investors transacting in the primary market, ETFs’ “in kind” creation and redemption process helps further enhance tax efficiency.

From a practical standpoint, many traditional equity index funds have been nearly as tax-efficient as their ETF counterparts because they’ve had inflows rather than redemptions. But investors who are concerned about tax efficiency have an additional safeguard in ETFs because of their structure. It’s also worth noting that Vanguard ETFs are a bit of an outlier in this discussion, in that their ETFs are share classes of the traditional index funds. As such, they’re vulnerable to redemptions from the traditional index funds.

Exposure to Major Market Segments: Tie

At this point, investors seeking exposure to a core capitalization-weighted index—whether it’s tracking US stocks, foreign stocks, or bonds, or various subasset classes and sectors—will be able to find it in either traditional index fund or ETF form.

Variations/Strategic-Beta Opportunities: Advantage ETFs

Whereas investors seeking “vanilla” capitalization-weighted index funds will find worthy representatives among traditional index funds and ETFs, most of the innovation in the “strategic-beta” or factor investing areas have come in the ETF space. Ditto for index products that invest in multiple asset classes. And while actively managed ETFs are a small share of the ETF universe (in number and in assets), they’ve grown rapidly over the past few years.

Ability to Buy In With a Low Dollar Amount: Advantage ETFs

Schwab leads the way in terms of offering low-cost traditional index funds without minimum initial investments. Yet investors can gain exposure to a huge swath of index products via ETFs with the purchase of as little as a single share. The downside of transacting in ETFs for very small investors is that commissions may apply (see above), which can take a big bite out of any gains.

Ability to Reinvest Dividends and Capital Gains: Advantage Traditional Index Funds

For investors who reinvest their dividends and capital gains, the process is a bit more seamless for traditional index fund investors than ETF investors. While most brokerage firms now provide dividend and capital gains reinvestment programs without additional fees for their ETF and equity investors, the process of reinvesting dividends and capital gains is as simple as checking a box for mutual fund investors.

Falling Mutual Fund and ETF Fees a ‘Big Win for Investors’

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The author or authors do not own shares in any securities mentioned in this article. Find out about Morningstar’s editorial policies.

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About the Authors

Christine Benz

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Christine Benz is director of personal finance and retirement planning for Morningstar, Inc. She is also the author of a new book, How to Retire: 20 Lessons for a Happy, Successful, and Wealthy Retirement (Sept. 2024, Harriman House). She co-hosts a podcast for Morningstar, The Long View, which features in-depth interviews with thought leaders in investing and personal finance.

Benz joined Morningstar in 1993. Before assuming her current role she served as a mutual fund analyst and headed up Morningstar’s team of fund researchers in the U.S. She also served as editor of Morningstar Mutual Funds and Morningstar FundInvestor.

She is a frequent public speaker and is widely quoted in the media, including The New York Times, The Wall Street Journal, Barron’s, CNBC, and PBS. In 2020, Barron’s named her to its inaugural list of the 100 most influential women in finance; she appeared on the 2021 list as well. In 2021, Barron’s named her as one of the 10 most influential women in wealth management.

She holds a bachelor’s degree in political science and Russian language from the University of Illinois at Urbana-Champaign.

Margaret Giles

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Margaret Giles is a content development editor for Morningstar. With a focus on individual investors, she supports digital content experiences that cover a range of topics, including portfolio decisions and other personal finance questions.

Giles joined Morningstar's editorial team in 2019 as a data journalist for She transitioned to her current position in content development in 2023. Giles holds bachelor's degrees in economics and Spanish from Grinnell College.

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