What is an ETF, and how does it work?

ETF rules, tax treatment, trading access and product names differ by country. Check the documents and regulator information that apply where you live.

What “pooled investment” means

Many investors place money into one fund. The fund uses that combined money to hold a portfolio. Each unit represents a small interest in that portfolio. The value of the unit changes as the holdings change, after costs and other effects.

The portfolio may be broad, such as many companies across a market, or narrow, such as one industry, commodity or theme. The structure can simplify access, but it does not turn a narrow portfolio into a broad one.

Why “exchange-traded” matters

ETF units trade on an exchange during market hours. Their market price can change throughout the day. A traditional mutual fund is often bought or redeemed with the fund at a price based on the end-of-day net asset value, although local practices differ.

Trading flexibility is not automatically an advantage. Frequent buying and selling can add spreads, brokerage charges, tax consequences and emotional decisions.

Market price and net asset value

Net asset value, or NAV, is the value of the fund’s assets minus its liabilities, usually expressed per unit. Market price is the price at which buyers and sellers trade the ETF on the exchange. The market price can sit slightly above NAV, called a premium, or below NAV, called a discount.

For a large, liquid ETF the difference may often be small, but that is not guaranteed. Less liquid holdings, market stress, time-zone differences and trading demand can widen it.

What can an ETF hold?

Index-tracking and actively managed ETFs

An index-tracking ETF aims to follow a defined index. An actively managed ETF gives a manager more freedom to choose or change holdings within the stated objective. Both can gain or lose money. “Passive” describes the approach to following an index; it does not mean the holdings are low risk.

Before investing, read the objective and methodology. A fund that follows a narrow or complex index can be more concentrated than an actively managed broad fund.

Costs are more than the expense ratio

• Ongoing fund cost: Often shown as an expense ratio or ongoing charges figure.
• Bid–ask spread: The difference between the price buyers offer and sellers ask.
• Broker or platform cost: A trade, custody or account charge may apply.
• Premium or discount: The market price may differ from NAV.
• Tax: Dividends, distributions, gains and foreign holdings may be treated differently by country.
• Currency conversion: Buying or selling in another currency can add cost even when the fund is unhedged or hedged.

A low headline fee is useful information, but it is not proof that the fund is suitable or cheapest for your way of investing.

Diversification: Helpful, but not automatic

An ETF holding hundreds of securities can reduce the effect of one company failing. Yet the portfolio may still be concentrated in one country, sector, currency or group of very large companies. Several ETFs can also overlap heavily, giving the appearance of diversification without adding much.

Look at the top holdings, sector and country weights, index method and any limits on concentration.

Physical and synthetic structures

Some ETFs hold the assets directly or use a representative sample. Others use derivatives or swap agreements to produce the intended return. The words “physical” and “synthetic” describe structure, not a simple good-versus-bad ranking. Each structure has risks, costs and rules that should be understood from the product documents.

For a beginner, awareness is enough: Ask how the fund gets its exposure and what could prevent it from matching the promised objective.

Currency risk

An ETF may trade in one currency while its holdings earn money in several others. The trading currency alone does not remove currency exposure. Some funds hedge part of the currency movement; others do not. Hedging can reduce one risk but introduces costs and may not remove every currency effect.

ETF versus an individual share

ETF versus a mutual fund

Both can pool investors’ money and hold similar assets. ETFs normally trade on an exchange during the day. Traditional mutual funds often transact directly with the fund at a calculated price. Minimum amounts, automatic contributions, fractional units, disclosures, tax treatment and charges differ by country and provider.

Neither wrapper is universally better. Start with the investment objective and holdings, then compare access, cost, tax and practical use.

Worked comparison: Broad does not mean identical

Imagine three unnamed ETFs:

All three are ETFs. Their risk comes from very different holdings. That is why the wrapper cannot replace analysis of the portfolio.

Questions to ask before investing

1. What objective does the ETF state?
2. Which assets, countries, sectors and currencies does it hold?
3. Does it track an index or use active decisions?
4. How concentrated are the largest holdings?
5. How does it obtain exposure: Direct holdings, sampling, futures or swaps?
6. What are the ongoing fee, spread, broker cost and tax implications?
7. How liquid is the ETF and its underlying portfolio?
8. Does it overlap with investments you already own?
9. Can you explain how it could lose money?
10. Is it a conventional long-term product or a complex leveraged/inverse product?

Common mistakes

• Assuming every ETF is diversified.
• Choosing a fund only because its recent return was high.
• Looking only at the expense ratio.
• Buying several funds without checking overlap.
• Confusing the currency printed beside the price with the currency risk of the holdings.
• Treating leveraged or inverse ETFs as ordinary long-term index funds.

Frequently asked questions