What is an ETF?

An ETF (exchange-traded fund) is a basket of securities — stocks, bonds, or other assets — that trades on an exchange like a single stock throughout the day. Most ETFs track an index and carry lower fees than actively managed mutual funds. All investing involves risk, including possible loss of principal.

An exchange-traded fund (ETF) holds a collection of assets — often all the stocks in an index like the S&P 500 — and issues shares that trade on a stock exchange throughout the trading day, just like individual stocks. This means you can buy or sell an ETF at market price any time the exchange is open, unlike a mutual fund (which prices once daily). The SEC's ETF overview covers the fundamentals in plain language.

How ETFs track an index

The majority of ETFs are index ETFs — they hold the same securities, in the same proportions, as a benchmark index (for example, the S&P 500, a total bond market index, or an international equity index). Because the fund isn't paying analysts to pick stocks, management costs are minimal. Expense ratios on broad index ETFs often fall below 0.10% annually. The tradeoff: an index ETF will never beat the market — it is the market (less fees).

ETFs trade intraday at market prices; mutual fund NAV is set once per day after close.
Most ETFs are passively managed and track a published index.
Expense ratios on index ETFs are typically very low — often under 0.20% annually.
ETFs may distribute capital gains and dividends, which can be taxable in a taxable account.
All investing involves risk, including possible loss of principal.

ETFs vs. mutual funds: practical differences

For most individual investors, the key practical differences are: (1) trading flexibility — ETFs trade like stocks, mutual funds don't; (2) minimum investment — many ETFs can be bought for the price of one share (some brokers offer fractional shares), while mutual funds often have minimums of $500–$3,000; (3) tax efficiency — ETF structure typically generates fewer taxable capital-gain distributions than equivalent mutual funds. Neither structure is universally superior — the right choice depends on your goals and tax situation. Consult a qualified financial advisor for personal guidance.

Where ETFs fit in a portfolio

ETFs are commonly used inside retirement accounts (IRAs, 401(k)s) and taxable brokerage accounts alike. Because they can represent entire market segments in a single trade, they're a popular tool for building diversified exposure without picking individual stocks. You can look up any registered ETF's filings via SEC EDGAR search. This page is educational only and does not constitute investment advice.

What the SEC says about ETFs

ETFs are registered investment companies whose shares are bought and sold on a national securities exchange at market prices throughout the trading day. — SEC / Investor.gov
Like mutual funds, ETFs offer investors a way to pool their money in a fund that makes investments in stocks, bonds, or other assets. — SEC / Investor.gov
ETF investors should review the fund's prospectus, which discloses investment objectives, strategies, risks, fees, and expenses, before investing. — SEC / Investor.gov

Key takeaways

An ETF holds a basket of securities and trades on an exchange throughout the day like a stock.
Most ETFs are index-based and carry very low expense ratios — check before you buy.
ETFs trade intraday; mutual funds price once daily after market close.
ETF structure is generally tax-efficient, but distributions in taxable accounts may still be taxable.
All investing involves risk, including possible loss of principal — read the prospectus first.