Exchange-traded funds (ETFs) can be a straightforward way for beginners to start investing. They offer access to diversified portfolios of stocks, bonds and other assets through a single investment, often at a relatively low cost. Instead of researching individual companies and managing a portfolio of stocks, investors can buy an ETF that tracks a broad market index.

That simplicity has also made ETFs a cornerstone of the Bogleheads approach to investing, a strategy popular among long-term investors and the Financial Independence, Retire Early (FIRE) community. Inspired by Vanguard founder John C. Bogle, the Bogleheads method emphasizes low fees, broad diversification and a long-term approach rather than trying to time the market.

However, be aware that ETFs have different tax treatment from traditional investment funds, which can affect how investors manage and rebalance their portfolios.

What is an ETF?

An exchange-traded fund is an investment fund that holds a collection of assets, such as stocks, bonds or commodities, and trades on a stock exchange like an individual stock.

When you buy shares of an ETF, you gain exposure to the assets held by the fund. Rather than purchasing shares in each company individually, you can invest in a broad portfolio through a single transaction.

For example, an ETF that tracks the S&P 500 gives investors exposure to the large US companies included in that index. Other ETFs track international stock markets like Spain’s IBEX 35, bond indexes, specific industries or particular investment strategies.

ETFs can be actively or passively managed. Passive ETFs generally aim to replicate the performance of an index, while actively managed ETFs use a portfolio manager to select investments in an attempt to achieve a particular objective.

How do ETFs work?

Most ETFs pool money from investors to purchase a portfolio of assets. The fund then issues shares that investors can buy and sell on an exchange.

An ETF's performance depends on the assets it holds and the investment strategy it follows. An index ETF, for example, aims to track a benchmark rather than select investments in an effort to outperform the market.

ETFs trade throughout the trading day, so their market prices fluctuate as investors buy and sell shares. This differs from traditional mutual funds, which are generally priced once per day using their net asset value.

ETF prices can trade slightly above or below the value of the underlying assets. Authorized participants help keep market prices close to net asset value through a process of creating and redeeming ETF shares.

For individual investors, the process is straightforward: choose an ETF, place an order through a brokerage account and hold the investment for as long as it fits your financial goals and risk tolerance.

Why ETFs are popular with long-term investors

ETFs appeal to investors who want to build wealth over time without having to select and manage individual securities. Their main advantages include:

Diversification: A single ETF can provide exposure to dozens, hundreds or even thousands of securities. Broad diversification can reduce the impact of any one company performing poorly, although it cannot eliminate market risk.

Low investment costs: Many index ETFs have relatively low annual management fees because they track an index rather than rely on a team of managers to select securities. Investors should also consider brokerage commissions, bid-ask spreads and other charges.

Convenience: ETFs make it possible to invest in broad markets, specific sectors or different asset classes through a brokerage account. Investors can build and maintain a portfolio without buying every underlying security individually.

Intraday trading: Unlike traditional mutual funds, ETFs can be bought and sold throughout the trading day at market prices. This provides flexibility, although frequent trading can increase costs and encourage unnecessary portfolio changes.

Transparency: Many ETFs disclose their holdings daily, allowing investors to see which assets they own indirectly and how the fund is invested.

Access to different markets: ETFs offer exposure to domestic and international stocks, bonds and other asset classes that may otherwise be difficult or expensive for individual investors to access.

ETFs are not automatically low-risk or tax-efficient. Their risk depends on what they hold, and their tax treatment depends in part on where the investor lives and the type of fund involved.

ETFs vs. mutual funds: Which is different in Spain?

ETFs and traditional mutual funds both pool investors' money into portfolios of assets. The main differences involve how they trade, their costs and, for Spanish residents, how gains are taxed.

The Spanish tax treatment: ETFs vs. investment funds

For investors who are tax residents in Spain, one of the most important differences is the tax treatment of transfers between qualifying investment funds.

Traditional investment funds (fondos de inversión): Under Spain's tax rules, qualifying investment funds can benefit from a tax deferral mechanism known as a traspaso. Investors can transfer their investment from one eligible fund to another without immediately paying capital gains tax. The original investment's acquisition value and date carry over to the new fund, and tax is generally due when the investment is eventually redeemed outside the qualifying transfer system.

ETFs (fondos cotizados): ETFs generally do not qualify for this tax deferral regime. Selling ETF shares at a profit is normally a taxable event, even if the proceeds are immediately reinvested in another ETF. Any taxable gain must be reported under the applicable Spanish tax rules.

The tax rules depend on the fund's legal structure and eligibility, not simply on whether a broker or investment platform is regulated. Before investing, check the fund's status and the tax treatment applicable to your circumstances. A Spanish tax advisor can help clarify how the rules apply to your portfolio.

How to start investing in ETFs in Spain

Investors in Spain can buy ETFs through banks, online brokers and investment platforms. Before opening an account, check the provider's regulatory status, fees and available products.

When choosing an ETF, consider the following:

• Investment objective: Decide whether you want exposure to global stocks, US equities, bonds or another market or asset class.

• Diversification: Check which securities and markets the ETF holds. A fund focused on one sector or country may carry more concentrated risk than a broad-market fund.

• Expense ratio: Compare the fund's annual management costs, often expressed as its ongoing charges figure (OCF) or total expense ratio (TER).

• Tracking difference: Review how closely the ETF has followed its benchmark after fees and other expenses.

• Fund structure: Check whether the ETF distributes income or reinvests it, its domicile, and whether it is eligible for sale to retail investors in the EU.

• Trading costs: Consider brokerage commissions, bid-ask spreads and any currency-conversion charges.

Large ETF providers include Vanguard, iShares and SPDR. However, the provider's name alone does not determine whether a fund is suitable for your portfolio.

Investors should also consider their time horizon, financial goals and ability to withstand losses. A diversified ETF portfolio can still fall sharply during a market downturn, and past performance does not guarantee future returns.

What is the role of ETFs in a FIRE strategy?

The FIRE movement focuses on building enough wealth to achieve financial independence, potentially allowing people to retire before the traditional retirement age.

Low-cost, broadly diversified index ETFs are frequently used in FIRE portfolios because they can provide exposure to financial markets without requiring investors to select individual stocks or actively trade.

The Bogleheads approach aligns with this strategy through a few core principles: invest regularly, keep costs low, diversify across markets and maintain a long-term perspective.

For example, an investor pursuing FIRE might make regular contributions to a diversified portfolio of stock and bond funds, adjusting the allocation as their goals and time horizon change. The aim is to participate in long-term market growth while managing risk and keeping investment costs under control.

However, ETFs do not guarantee financial independence or positive returns. Reaching FIRE depends on factors such as savings rate, investment performance, spending needs, taxes and the length of time invested. Calculate your FIRE number here.

Frequently asked questions about ETFs

What does ETF stand for?

ETF stands for exchange-traded fund. It is an investment fund that holds a portfolio of assets and trades on a stock exchange.

How do ETFs make money?

Investors can earn returns through increases in an ETF's share price and, where applicable, distributions such as dividends or interest. Returns depend on the performance of the underlying investments, minus fees and other costs.

Are ETFs good for beginners?

ETFs can be useful for beginners because they offer access to diversified portfolios through a single investment. Broad-market index ETFs are often used in long-term investing strategies, but investors should understand the fund's risks, costs and tax treatment before investing.

Can you lose money investing in ETFs?

Yes. ETF prices can fall when the underlying assets lose value. Diversification can reduce the effect of an individual investment performing poorly, but it cannot prevent losses across a market or asset class.

Are ETFs better than mutual funds in Spain?

ETFs and traditional investment funds have different features, costs and tax treatment. ETFs trade throughout the day, while qualifying traditional investment funds may allow investors to defer capital gains tax when transferring between eligible funds. Which structure is appropriate depends on an investor's goals, trading needs and tax circumstances.

Where can I buy ETFs in Spain?

ETFs are available through banks, online brokers and investment platforms that provide access to exchange-traded products. Before opening an account, verify the provider's regulatory status and review its fees, available ETFs and investor protections.

Are ETFs part of the Bogleheads investment strategy?

Yes. Low-cost, diversified index ETFs can be used to implement the Bogleheads approach, which emphasizes long-term investing, broad diversification and minimizing fees. Traditional index mutual funds can also be used to follow the same principles.