What an ETF is and how it trades

An exchange-traded fund (ETF) is a basket of investments bundled together and sold as a single security on a stock exchange. You buy and sell ETF shares the same way you buy and sell individual stocks — through a brokerage account, during market hours, at a price that changes throughout the day. The price you pay depends on what other buyers and sellers are willing to pay at that moment, not on the value of the holdings inside.

That last part matters. An ETF might hold 500 different stocks, bonds, or commodities, but you do not have to buy all 500 separately. You buy one share of the ETF, and you own a small piece of all 500. If the ETF costs $100 per share and holds $100 worth of assets per share, you are getting exposure to all those holdings for a single transaction.

ETFs trade on exchanges like the NYSE or NASDAQ, just like Apple or Microsoft stock does. This means the price moves during the trading day, and you can sell your shares whenever the market is open. That is different from mutual funds, which only price once per day after the market closes.

Key Takeaways

  • An ETF is a collection of investments sold as a single share that trades on a stock exchange during market hours.
  • You buy ETF shares through a brokerage account the same way you buy individual stocks, and the price changes throughout the day.
  • ETFs charge annual fees (called expense ratios) that are deducted from the fund's value, typically ranging from under 0.1% to over 1% per year depending on the fund.
  • Most ETFs track an index like the S&P 500, meaning they hold the same stocks in roughly the same proportions as that index.
  • You can hold an ETF in a regular taxable brokerage account or inside a retirement account like an IRA or 401(k).

What is inside an ETF

The contents of an ETF depend on what the fund is designed to track. Many ETFs follow an index — a pre-set list of investments. The S&P 500 index, for example, includes 500 large U.S. companies. An S&P 500 ETF holds those same 500 stocks in roughly the same proportions, so when you buy the ETF, you own a piece of all 500.

Other ETFs hold bonds, commodities like gold or oil, international stocks, or a mix of different asset types. Some focus on a specific industry (technology, healthcare, energy) or a specific theme (dividend-paying stocks, companies with low debt, emerging markets). The fund manager decides what goes in based on the ETF's stated goal.

When a company joins or leaves an index, the ETF updates its holdings to match. You do not have to do anything — the fund handles the rebalancing automatically. This is one reason index-tracking ETFs tend to have lower fees than actively managed funds, where a manager is constantly buying and selling to try to beat the market.

How ETF fees work

Every ETF charges an annual fee called an expense ratio. This is a percentage of your investment that the fund deducts each year to cover management, administration, and trading costs. A 0.05% expense ratio on a $10,000 investment costs $5 per year. A 1% expense ratio on the same $10,000 costs $100 per year.

The fee is taken from the fund's assets, not billed to you separately. If an ETF grows 8% in a year but has a 0.5% expense ratio, you see roughly 7.5% growth (the math is slightly more complex, but that is the idea). Over decades, even small differences in fees compound significantly.

Index-tracking ETFs typically have lower expense ratios — often under 0.2% — because they straightforward hold the same investments as an index and do not require active management. Actively managed ETFs, where a manager picks holdings to try to outperform the market, usually charge more, sometimes 0.5% to 1% or higher.

You may also pay a commission when you buy or sell ETF shares, depending on your brokerage. Many brokerages now offer commission-free ETF trading, so check your account before you trade.

How ETF prices work during the trading day

An ETF has two prices: the net asset value (NAV) and the market price. The NAV is what the fund's holdings are worth per share, calculated once per day after the market closes. The market price is what buyers and sellers are willing to pay right now, during trading hours.

Most of the time these prices are very close. But during periods of heavy trading or market stress, they can drift apart. If many people are selling an ETF at once, the market price might drop below the NAV. If many people are buying, the market price might rise above it. This gap is called a premium (price above NAV) or discount (price below NAV).

For most popular ETFs, especially those that track major indexes, premiums and discounts are tiny — often just a few cents on a $100 share. But for smaller or more specialized ETFs, the gap can be larger. This is one reason to check the bid-ask spread (the difference between what buyers will pay and what sellers are asking) before you trade an ETF with low trading volume.

How to buy and hold an ETF

You need a brokerage account to buy ETF shares. This can be a regular taxable account or a retirement account like a traditional IRA, Roth IRA, or 401(k). Once your account is open and funded, you search for the ETF by its ticker symbol (a short code like SPY for the SPDR S&P 500 ETF), enter the number of shares you want, and place your order.

Your order goes through during market hours (9:30 a.m. to 4 p.m. Eastern time on weekdays) at whatever price the market is trading at when your order executes. If you place an order after the market closes, it will execute the next trading day.

Once you own the shares, you hold them in your account. You do not have to do anything unless you want to sell. Some ETFs pay dividends (distributions of cash from the fund's holdings), which are automatically reinvested or paid to you depending on your account settings. You can hold an ETF for years, or sell it whenever you want during market hours.

ETFs versus mutual funds and individual stocks

An ETF sits between a mutual fund and individual stocks in terms of how it works. Like a mutual fund, an ETF gives you when ready diversification — one purchase gets you exposure to many holdings. Like a stock, an ETF trades during the day at a price that changes minute to minute, and you can sell whenever you want.

Mutual funds only price once per day, after the market closes, so you cannot sell at a specific intraday price. ETFs also tend to have lower expense ratios than actively managed mutual funds, though some mutual funds (especially index funds) charge similarly low fees. ETFs are generally more tax-efficient than mutual funds because of how they are structured, though this matters more in taxable accounts than in retirement accounts.

Individual stocks give you ownership in one company. An ETF gives you ownership in many. Stocks can be more volatile and require more research to pick, but they also have no expense ratio. ETFs are simpler if you want broad exposure without picking individual companies.

Tax treatment of ETFs

In a taxable brokerage account, you owe capital gains tax when you sell an ETF share for more than you paid for it. If you held the ETF for more than one year, you pay long-term capital gains tax, which is usually lower than short-term rates. You also owe tax on any dividends the ETF pays, though some dividends may have access to for lower tax rates.

Inside a retirement account like a traditional IRA or 401(k), you do not owe tax on gains or dividends while the money is in the account. You pay tax later when you withdraw. In a Roth IRA, you do not owe tax on gains or withdrawals at all, as long as you follow the account rules.

ETFs are generally more tax-efficient than mutual funds in taxable accounts because of their structure, but the difference matters most if you trade frequently or hold the fund for a long time. If you are holding for decades, the tax advantage is meaningful.

Frequently Asked Questions

Can I lose money in an ETF?

Yes. If the value of the holdings inside the ETF drops, the ETF share price drops too. An ETF that holds stocks can fall 20%, 30%, or more during a market downturn. An ETF that holds bonds is generally less volatile but can still lose value if interest rates rise or the bond issuer defaults. The only way to avoid this risk is to hold cash or very safe investments, which come with their own trade-offs.

Do I get voting rights if I own an ETF?

No. When you own an ETF, you own shares of the fund, not shares of the individual companies inside it. The fund holds the voting rights, not you. Some ETFs pass through voting rights to shareholders, but this is uncommon and varies by fund.

What is the difference between an ETF and an index fund?

An index fund is a mutual fund or ETF that tracks an index. So all index funds are either mutual funds or ETFs, but not all ETFs are index funds — some are actively managed. The key difference is how they trade: index mutual funds price once per day, while index ETFs trade throughout the day like stocks.

Can I buy ETFs inside a 401(k)?

It depends on your plan. Some 401(k) plans offer a limited menu of ETFs to choose from. Others only offer mutual funds. Check your plan documents or ask your plan administrator what investment options are available. IRAs typically offer a much wider range of ETFs through most brokerages.

How much money do I need to start buying ETFs?

You need enough to buy at least one share. If an ETF costs $100 per share, you need $100 plus any commission (though many brokerages now offer commission-free trading). Some brokerages have account minimums, but many do not. Check your brokerage's requirements before you open an account.