What is an ETF?

What is an ETF?

ETF stands for Exchange Traded Fund. It is an investment fund admitted to trading on a stock exchange whose main goal is to deliver performance linked to the behaviour of a reference indicator, that is, an index¹.

The idea has two halves: on the outside, you buy and sell it like a share, throughout the day and at the market price; on the inside, it is a basket of many assets (shares, bonds or others). When you buy one unit of a world equity ETF, you become indirectly exposed to hundreds or thousands of companies at once.

How does an ETF work?

Most ETFs track an index, such as the S&P 500 (the largest US companies), a world equity index or the PSI-20 (Portugal's main listed companies). The fund aims to replicate that index: if the index holds certain companies at certain weights, the ETF holds them in the same proportion. So its value rises and falls in line with the index it tracks.

Because the portfolio is defined by the index rather than by a manager picking assets one by one, this is called passive management. That is what keeps the costs low, the point we come back to below.

What is the difference between an ETF and a traditional fund?

An ETF and a "classic" investment fund are, at heart, the same thing: baskets of assets managed by a fund company. What changes is how you trade them²:

Neither is "better" in absolute terms: the ETF offers flexibility and low costs; a traditional fund can make sense for someone who prefers to subscribe directly at the bank or wants an active strategy.

What is passive management?

Passive management means the ETF simply follows an index instead of trying to beat the market. There is no team deciding to buy company A and sell company B hoping to get it right; the ETF copies the index. The upside is twofold: much lower costs and transparency (you always know what the fund holds).

The flip side is that a passive ETF will never beat the index it tracks, by design. If the market falls, the ETF falls too. Following the market is not the same as being protected from it.

Accumulating or distributing ETF?

Companies pay dividends. What the ETF does with that money defines two versions of the same fund:

• Accumulating (often marked Acc): dividends are reinvested automatically inside the fund. You receive no cash, but the ETF's value grows, benefiting from compounding over time, the very same principle behind compound interest.
• Distributing (Dist): dividends are paid periodically into your account, as income, rather than staying inside the fund.

The choice is about your goal, growing your capital (accumulating) or receiving regular income (distributing), and it has different tax implications. In Portugal, how each is taxed is explained in the article on funds and ETFs in your tax return.

How much does an ETF cost? The TER

The core cost of an ETF is the TER (Total Expense Ratio): the fund's annual fee, expressed as a percentage of the amount invested and already reflected in the value (you get no invoice; the cost is deducted continuously). For broad-index ETFs the TER is usually low, often between 0.05% and 0.30% a year, whereas many actively managed funds charge 1% to 2%.

On top of this come your broker's fees where you buy the ETF: buy and sell orders and sometimes custody. Small differences in the TER look insignificant, but over many years they make a real difference to the final outcome.

What is a UCITS ETF?

When you buy an ETF in Europe, you often see the UCITS acronym in its name. UCITS is the European framework that regulates funds sold to retail investors in the European Union, with rules on diversification, transparency and investor protection. ESMA requires such a fund to use the "UCITS ETF" identifier in its name and documents³, and to provide a Key Information Document setting out the costs and risks.

In Portugal, funds and ETFs are supervised by the CMVM¹. In practice, the UCITS label signals that the product follows the European rules protecting retail investors.

A worked example: €5,000 in a world equity ETF

Suppose you invest €5,000 in an accumulating ETF that tracks a world equity index, with a TER of 0.20% a year. The fund's annual cost is roughly:

€5,000 × 0.20% = €10 per year

For ten euros a year you are exposed to hundreds of companies across many countries. If the index rises, your ETF's value rises; if it falls, it falls with it, and the companies' dividends are reinvested automatically inside the fund (because it is accumulating). This figure is illustrative and not a forecast: markets do not rise in a straight line. To see how an amount might evolve at different annual rates, use the investment return calculator.

What are the risks of investing in an ETF?

An ETF has no guaranteed capital. The main risks to keep in mind:

• Market risk: if the index falls, the ETF falls. You can get back less than you invested.
• Currency risk: if the ETF is priced in another currency (for example, dollars), the euro/dollar exchange rate also affects the outcome.
• Costs: the TER and broker fees reduce returns over time.

An ETF is a low-cost diversification tool, but it is still an investment exposed to market swings. Once the concept is clear, the natural next step is to try the numbers for your own case in the investment return calculator.