What Is an ETF? A Beginner's Guide to Exchange-Traded Funds

An exchange-traded fund (ETF) is a fund that holds a collection of investments, such as stocks or bonds, and sells shares of itself on a stock exchange. When you own a share of an ETF, you own a small slice of everything the fund holds. Think of it as one basket of many investments bought in a single trade, at a price that updates all day.

If you are opening your first brokerage account, you will see the letters ETF almost immediately. This guide explains what an ETF is in plain English, how one works behind the scenes, the main types, what ETFs cost, how people buy them, how they are generally taxed and where the risks sit. Nothing here is a recommendation. The aim is to make the choices on a brokerage screen easier to understand.

What Is an Exchange-Traded Fund (ETF)?

Start with the word fund. A fund is a pool of money collected from many investors and used to buy a basket of investments. Each investor owns shares of the fund, and each share represents a proportional piece of the whole basket. The investments inside the basket are called the fund's holdings.

An exchange-traded fund is a fund whose shares are listed on a stock exchange. Instead of placing an order that is processed once at the end of the day, an investor can buy or sell ETF shares at any moment the market is open, at whatever price the market is offering right then.

FINRA, the self-regulatory organization that oversees US brokerage firms under SEC supervision, describes ETFs as pooled investment products and notes that ETF shares trade like stocks and can be bought or sold throughout the trading day.

Many ETFs are built to follow an index, which is a published list of securities used to measure a part of the market. An index might track a large group of well-known companies, or a broad slice of the bond market.

A fund that aims to match the results of an index, rather than trying to beat it, is called an index fund. An ETF that follows an index is therefore one kind of index fund, packaged so that it trades on an exchange. If that idea is new, the guide on how index funds work covers it in depth.

One more term belongs here. Diversification means spreading money across many holdings so that the poor results of one are less likely to dominate the whole. A single ETF can hold dozens, hundreds or thousands of securities.

How Does an ETF Work?

The fund owns the holdings, and the investor owns shares of the fund. Shareholders do not own the individual stocks or bonds directly, and they generally do not vote on them or receive them. What a shareholder owns is a claim on a proportional share of the fund's assets, after the fund's expenses.

Every ETF is run by a fund company, often called the fund manager or sponsor, which writes down the rules in a document called a prospectus. The prospectus explains what the fund aims to hold, how it chooses its holdings and what it charges. For an index ETF, the rules are simple: hold the securities in the index in roughly the same proportions.

Price versus NAV

An ETF has two related numbers. The first is its net asset value (NAV), which is the total value of everything the fund holds, minus its liabilities, divided by the number of shares. The second is its market price, which is what buyers and sellers are actually paying for a share on the exchange at a given moment.

The two are usually close, but they are not identical. FINRA notes that retail investors may transact at prices that can deviate from the value of the underlying holdings.

Creation and redemption in plain terms

Something has to keep the market price close to NAV. That job falls to large financial institutions known as authorized participants. They can work directly with the fund to create new ETF shares by delivering a basket of the underlying securities, or to redeem shares by handing them back in exchange for securities. Because they work in large blocks, they have a reason to trade away any meaningful gap between price and value.

Ordinary investors never take part in this step. They trade with other investors on the exchange, through a brokerage, while the large institutions work in the background. The mechanism helps explain why most index ETFs trade close to the value of what they own, though it does not guarantee that they always will.

Where the return comes from

An ETF can deliver returns to its owners in two ways. The first is a change in the share price, up or down, as the value of the holdings changes. The second is a dividend distribution, which is a payment of the income the fund has collected from its holdings, such as company dividends or bond interest, passed on to shareholders. Some ETFs pay out income regularly, others pay very little, and the amounts depend entirely on what the fund holds.

Main Types of ETFs

ETFs are grouped by what they hold. The categories below describe what each kind contains; none of them is a recommendation.

• Broad stock index ETFs hold a wide range of company shares, such as a large share of the companies in a national market. Their results follow the index they track.
• Bond ETFs hold bonds, which are loans made to governments or companies that pay interest. Their value moves with interest rates and with the creditworthiness of the borrowers.
• Sector ETFs hold companies from one industry, such as healthcare or energy. Because they cover a narrower slice, they are less diversified than a broad index fund.
• International ETFs hold companies or bonds from outside the investor's home country. Their results also depend on currency movements.
• Commodity ETFs give exposure to raw materials such as metals or energy. Some hold the physical material, while others hold contracts tied to its price, and those structures can behave differently.

Within each group, funds differ in how they are built, what they charge and how closely they track their target. The fund's prospectus and fact sheet show exactly what a particular ETF holds.

A caution on leveraged and inverse ETFs

A small number of ETFs are designed differently from the categories above. Leveraged ETFs aim to deliver a multiple of an index's daily result, and inverse ETFs aim to deliver the opposite of it. Both are complex products.

FINRA has explained that most of these funds reset daily, meaning they are designed to meet their stated objective on a daily basis, and that their performance over longer periods can differ significantly from that daily objective. FINRA has also said that leveraged and inverse ETFs typically are not suitable for retail investors who plan to hold them for more than one trading session.

Anyone who encounters one of these products will want to read the prospectus carefully and understand that it works very differently from an ordinary index ETF.

ETF vs Mutual Fund: The Short Version

A mutual fund is also a pooled fund that holds many securities, so the two products have a lot in common. The practical differences come down to how they are bought and sold.

Both product types can follow an index, both charge an expense ratio, and both can be held in the same kinds of accounts. Costs, tax treatment, minimums and trading features differ from fund to fund, and the details deserve their own walk-through. The article on ETFs versus mutual funds lays out that comparison side by side.

What Do ETFs Cost?

Owning an ETF has an ongoing cost and, depending on how it is traded, some occasional trading costs. The ongoing cost is the more important one to understand, because it never switches off.

The expense ratio

The expense ratio is the annual fee a fund charges for running itself, expressed as a percentage of the money invested. A fund with a 0.20% expense ratio takes 0.20% of the assets each year, which is $20 a year for every $10,000 invested.

There is no bill for it. The fee is taken out of the fund's assets, so it quietly reduces the fund's return instead of appearing as a separate charge.

FINRA notes that expense ratios are calculated as a percentage of the assets invested, and that ETFs generally do not carry loads or 12b-1 fees (sales and marketing charges that some mutual funds add). The Investment Company Institute reported that the average expense ratio for index equity ETFs was 0.14% in 2025, and 0.09% for index bond ETFs. Averages hide a wide spread across individual funds.

A fee of a fraction of one percent sounds trivial, which is exactly why it is easy to overlook. The table below shows what happens to a purely hypothetical $10,000 over 30 years when only the expense ratio changes.

Here is how to read it. The calculation starts with a one-time $10,000, adds nothing further, and applies the fee as a percentage of the account balance each year. The 6% growth rate is a round number chosen only to show the arithmetic. It is not a forecast and not a historical average, and real returns vary from year to year and can be negative.

The pattern matters more than the exact dollar amounts. The 30-year result in the 1.00% row is $14,435 lower than in the 0.03% row, on the same starting amount and the same assumed growth. The fee seems small each year, but it is charged on a balance that is supposed to be growing, so the dollar cost grows with it.

The gap also builds gradually. Here are the same hypothetical figures at three points along the way.

After 10 years, the difference between the 0.03% row and the 1.00% row is $1,659. After 30 years it is $14,435. Compounding works on fees as it does on growth: money paid away early earns nothing later.

Different assumptions would produce different numbers. The compound interest calculator lets you change each input and watch the effect.

Trading costs and the bid-ask spread

Buying and selling can carry costs of their own. Some brokerages may charge a commission on trades, while others do not, so the cost depends on the account.

The second trading cost is built into the market itself. The bid-ask spread is the gap between the highest price a buyer is currently offering (the bid) and the lowest price a seller is currently asking (the ask). If the bid is $50.00 and the ask is $50.05, buying and immediately selling, with prices unchanged, would lose the $0.05 difference per share. Heavily traded ETFs tend to have narrow spreads, while thinly traded ones can have wider spreads.

How to Buy an ETF

Buying an ETF follows the same steps as buying a stock. The details differ slightly between brokerages, but the sequence is the same.

1. Open a brokerage account. A brokerage account is an account with a firm that is allowed to place trades on an exchange on the customer's behalf. It can be a taxable account or a retirement account such as an IRA, and the type of account affects how the investments are taxed.
2. Fund the account. Move money in from a bank account. Most brokerages show the balance as cash available to trade.
3. Find the ETF. Every ETF has a ticker symbol, a short code of letters used to identify it on the exchange. Enter the ticker in the brokerage's search box and read the fund's page, including its stated holdings, expense ratio and fact sheet. Before buying, it helps to check three things on that page: what the fund holds, what it charges and how heavily it trades.
4. Choose an order type. A market order tells the brokerage to buy right away at the price currently available. A limit order sets the maximum price the buyer is willing to pay, and it only executes if the market reaches that price or better.
5. Choose a quantity. Enter the number of shares. Some brokerages offer fractional shares, which allow a buyer to purchase a portion of a share by entering a dollar amount, rather than a number of whole shares.
6. Review and place the order. Check the ticker, the order type, the quantity and any estimated cost, then submit it. A confirmation appears, and the shares show up in the account once the trade is complete.

A market order prioritizes speed and a limit order prioritizes price control. A market order can execute at a price slightly different from the last one displayed, while a limit order might not execute at all.

How Are ETFs Taxed?

Tax treatment depends on the country, the account type and personal circumstances, so this section stays general. A tax professional can explain how the rules apply in a particular case.

In a taxable US brokerage account, there are generally two ways an ETF can create a tax event. The first is a distribution paid by the fund. Dividend distributions are generally taxable in the year they are received, and so are capital gains distributions, which are payments made when a fund sells holdings at a profit and passes the gain on to shareholders. The second is selling ETF shares for more than was paid for them, which generally creates a capital gain.

Many ETFs have a reputation for distributing fewer capital gains than comparable mutual funds. Part of the reason is the creation and redemption process described earlier. Because large institutions often exchange baskets of securities with the fund instead of cash, the fund may be able to move out holdings that were bought at much lower prices without selling them for a taxable gain.

This is a feature of how many funds are structured, not a guarantee. ETFs can and do distribute capital gains, and the outcome depends on the fund and its holdings.

Account type also matters, because investments held inside a tax-advantaged retirement account follow that account's own rules.

ETF Risks

An ETF is an investment, and investing involves risk, including the possible loss of the money invested. The main risks are worth stating plainly.

• An ETF is not guaranteed. Its value is not promised or protected by the fund company. The price on any day is whatever the market sets.
• Value moves with the holdings. If the securities inside an ETF fall in value, the ETF falls too. A stock ETF can decline sharply in a bad market, and a bond ETF can lose value when interest rates rise.
• Diversification does not prevent losses. Spreading money across many holdings reduces the effect of any single one, but it does not shield an investor from a broad decline in the market the fund follows.
• Narrow funds carry concentrated risk. A fund focused on one sector, one country or one commodity can move far more than a broad fund.
• Results can differ from the index and from NAV. An index ETF may not match its index exactly, and its market price can drift from its NAV, especially when markets are stressed or trading is thin.
• Some ETFs are complex products. Leveraged and inverse funds behave very differently from ordinary ETFs, as described earlier.
• Past performance does not guarantee future results. A fund's history describes what has happened, not what will happen.

An ETF is a tool whose behavior depends on what it holds, so understanding the holdings matters more than the label on the wrapper.

Frequently Asked Questions About ETFs

What is an ETF in simple terms?

An ETF is a basket of investments that can be bought as a single item on a stock exchange. Instead of purchasing dozens of individual stocks or bonds, an investor buys one share of the fund, which represents a small part of the whole basket. Its price moves throughout the trading day.

How is an ETF different from a stock?

A stock is a share in a single company, and its value depends on that one business. An ETF is a share in a fund that holds many securities, so its value depends on the combined results of everything inside it. Both trade on exchanges and can be bought through the same brokerage account, but an ETF spreads across many holdings, while a stock concentrates on one.

Is an ETF the same as an index fund?

Not exactly. An index fund is any fund that aims to match an index. An ETF describes how a fund is packaged, with shares that trade on an exchange. Many ETFs are index funds, but some ETFs follow other approaches, and many index funds are mutual funds rather than ETFs.

How do ETFs make money for investors?

Returns come from two places: changes in the price of the fund's shares, and income paid out as distributions, such as dividends or bond interest. Either can be positive or negative over any period, and neither is promised.

Can you lose money in an ETF?

Yes. An ETF's value rises and falls with the value of its holdings, so it is possible to lose some or all of the money invested. Diversification can reduce the effect of any single holding falling, but it does not prevent losses, and past performance does not guarantee future results.