ETFs are often presented as simple, inexpensive and already diversified instruments. In many cases these characteristics are real, but they can lead to a mistaken conclusion: assuming that buying an ETF automatically creates a cautious investment. It does not. An ETF is simply a vehicle providing exposure to a particular market, index or strategy. Its risk depends mainly on what it contains, how it tracks the benchmark and how concentrated that benchmark is.

To truly understand an ETF, you therefore need to look beyond its commercial name and ask at least four questions: which index does it track, which instruments does it contain, with what weights and through which replication method? A global equity ETF and an ETF concentrated in technology companies may both be ETFs, but their risk profiles are completely different.

What is an ETF?

ETF stands for Exchange Traded Fund. It is a fund or a variable-capital investment company (SICAV) traded on an exchange like a share. Index ETFs normally aim to track the performance of a reference index, known as a benchmark. Buying a unit of an ETF does not mean directly buying each security in the index, but a stake in the fund that holds or replicates that portfolio. Borsa Italiana describes ETFs as instruments combining certain features of funds, such as diversification through a basket of securities, with the exchange tradability typical of shares.

Suppose an ETF tracks an index comprising 500 companies. With a single purchase, the investor obtains indirect exposure to that basket without having to buy all 500 shares separately. This can substantially reduce company-specific risk, but it does not eliminate the risk of the entire reference market falling.

The distinction is fundamental: diversification reduces certain risks, not risk in general.

CONSOB notes that diversification helps contain a portfolio’s vulnerability to individual instruments, sectors or markets, but cannot eliminate the uncertainty associated with investing.

An ETF is not safe simply because it holds many securities

Imagine two ETFs. The first contains 1,500 companies spread across different countries and sectors. The second contains 100 companies, almost all from the same technology segment. Formally, both may be considered diversified compared with buying a single share, but the second remains heavily exposed to a single economic sector.

The same problem can occur geographically. An ETF may contain hundreds of securities but be entirely concentrated in one country. If that country’s economy, currency or financial market goes through a difficult period, all the fund’s components can be affected simultaneously.

CONSOB specifically stresses that diversification does not simply mean owning “many things”: if the instruments belong to the same market or sector, or respond to the same factors, risk can remain highly concentrated.

The number of securities in an ETF is therefore insufficient to measure the quality of diversification.

The main risk remains the underlying market

Suppose you buy an ETF tracking a global equity index. If the global stock market loses 30%, the ETF will suffer a similar loss, subject to differences arising from costs, replication and other factors.

The fact that the fund contains thousands of companies does not protect it from a general market crisis.

Borsa Italiana clarifies that ETFs remain exposed to the risk that shares, bonds or other instruments held in their assets lose value.

It is therefore important to distinguish between specific risk and systematic risk. The former concerns events affecting a single company or a few instruments and can be reduced through diversification. The latter concerns the whole market or a large part of it and does not disappear simply by increasing the number of securities.

A diversified ETF can therefore be much more robust than buying a single share, but can still lose a significant part of its value during a financial crisis.

An ETF’s name does not necessarily tell you how diversified it is

Another common mistake is reading words such as “World”, “Global” or “Europe” and automatically assuming the fund is evenly distributed.

Indices are constructed according to precise rules and often give greater weight to companies with larger market capitalisations. Consequently, a few large stocks may represent a significant share of the entire index.

Suppose an index contains 1,000 companies but the top ten represent 25% of its value. The investor formally owns 1,000 securities, but a quarter of the result still depends on just ten companies.

This does not necessarily make the index wrong. It simply means the total number of constituents does not describe its entire risk structure.

Before buying an ETF, it is therefore useful to examine at least:

Concentration risk can be hidden

The problem becomes particularly apparent in sector or thematic ETFs.

An ETF focused on artificial intelligence, cybersecurity, renewable energy or robotics may contain dozens or hundreds of companies. But if they all depend on the same economic, technological or regulatory factors, actual diversification can be much lower than it appears.

An investor may also own several ETFs believing they are highly diversified, when the same large stocks actually appear repeatedly in each fund.

For example, a global ETF, an S&P 500 ETF, a Nasdaq ETF and a technology-sector ETF might share many of the same companies. The investor would own four different instruments, but a substantial part of the portfolio could be exposed to the same stocks.

This is exactly the kind of “naive diversification” CONSOB warns about: the number of instruments is insufficient if underlying exposures are similar.

Physical and synthetic replication

Not all ETFs track their benchmark in the same way.

With physical replication, the fund directly buys all or a representative selection of the securities in the index. If the index contains 500 shares, the fund may hold those shares directly or use a sample capable of reproducing their performance.

With synthetic replication, the fund can instead obtain the index’s performance through derivatives, such as swap contracts entered into with a financial counterparty.

Synthetic replication is not necessarily worse. It can be useful when the underlying market is difficult or expensive to replicate directly and can also enable very accurate index tracking. However, it introduces an additional element to understand: counterparty risk, meaning the risk that the party to the contract fails to meet its obligations.

For European UCITS ETFs, limits and collateralisation systems exist to contain this risk, but the structure nevertheless remains more complex than simply holding securities directly.

The point is not to automatically avoid synthetic ETFs, but to know that two ETFs tracking the same index may use different mechanisms.

Tracking error: an ETF never tracks its index perfectly

If an index gains 10%, the ETF is not guaranteed to produce exactly 10%.

The difference between the ETF’s return and its benchmark’s return may depend on fees, trading costs, dividend taxation, replication methods, securities liquidity and other factors.

Tracking error measures how much the ETF’s behaviour deviates from that of its reference index.

Some deviation is inevitable. The fund incurs costs that the theoretical index does not, and must actually manage purchases, sales and rebalancing.

For this reason, an ETF with a very low TER is not necessarily the one that tracks the index best. Its historical behaviour relative to the benchmark should also be examined.

The TER is not the only cost

The TER, Total Expense Ratio, indicates the annual charges applied by the fund. ETFs generally have relatively low management costs, and Borsa Italiana highlights low fees as one of these instruments’ most appreciated features.

But the TER does not necessarily represent everything the investor pays.

When buying or selling an ETF, there may be:

An ETF with a TER of 0.10% can therefore have an effective cost above 0.10%, particularly if traded frequently or if it has wide spreads.

The spread is an often invisible cost

ETFs trade on an exchange with a purchase price, called the ask, and a sale price, called the bid. The difference between them is called the bid-ask spread.

Suppose an ETF can be bought for 100.20 euros and sold at the same moment for 100 euros. The spread is 0.20 euros, or approximately 0.20%.

Buying and immediately selling would therefore incur a small loss even without any market movement.

For highly liquid ETFs, the spread can be very narrow. For less frequently traded instruments or particular markets, it can be wider.

Borsa Italiana explains that the creation and redemption mechanism and the presence of specialist market participants normally help keep an ETF’s market price close to its net asset value, but deviations cannot be entirely ruled out.

ETF liquidity and underlying liquidity

An ETF may appear lightly traded when looking only at daily volume, but its liquidity also depends on the liquidity of the underlying securities and the functioning of the primary market.

Authorised participants can create or redeem units by exchanging them for the securities making up the benchmark. This mechanism tends to keep the fund’s price close to the value of the underlying assets.

However, during particularly difficult market conditions, spreads can widen and the ETF’s price may temporarily deviate further from the portfolio’s theoretical value.

Liquidity should therefore not be considered fully guaranteed under every market condition.

Currency risk is often underestimated

Imagine an Italian investor buying, in euros, an ETF consisting predominantly of US companies.

The fact that an ETF unit trades in euros does not necessarily mean dollar risk has disappeared. If the underlying assets are denominated in dollars, the investor may remain exposed to euro/dollar exchange-rate movements.

Borsa Italiana expressly highlights that when the reference index’s currency differs from the investor’s, exchange-rate changes can alter the result obtained.

Suppose the US shares in the fund rise by 10%, but the dollar loses 10% against the euro over the same period. The result for a European investor may differ substantially from the +10% observed in the American market.

ETFs with currency protection exist, often described as currency hedged, but hedging also has costs and is not perfect.

The fundamental point is that an ETF’s trading currency and the economic currency exposure of its underlying investments are two different things.

A bond ETF can lose value

Another common misconception concerns bond ETFs. Because bonds are often considered more cautious instruments than shares, some people may think a bond ETF cannot suffer significant losses.

In reality, bond values vary mainly with interest rates and issuers’ credit risk.

When market interest rates rise, existing bonds with lower coupons become less attractive and their prices tend to fall. The longer the portfolio’s duration, the greater its sensitivity to interest-rate changes may be.

An ETF holding very long-maturity bonds can therefore experience substantial fluctuations even if issuers continue to pay interest and principal regularly.

Equity ETFs and bond ETFs are therefore not respectively “risky” and “safe” categories. Both contain very different levels of risk.

Beware of leveraged and inverse ETFs

ETFs and structured instruments exist that are designed to achieve particular results, such as amplifying an index’s daily change or gaining when the market falls.

Borsa Italiana also distinguishes structured ETFs allowing leveraged or short exposure.

These products are significantly more complex than traditional index ETFs because leverage is normally applied to the benchmark’s daily change. Over longer periods, the outcome can therefore be very different from a simple multiple of the index’s overall performance.

For example, an ETF with leverage of 2 does not guarantee that if an index gains 20% in a year, the fund will necessarily gain 40%. The sequence of daily changes affects the outcome.

These instruments therefore require a much deeper understanding of the mathematics and risks involved.

ETFs and ETCs are not the same thing

Another often overlooked distinction concerns commodity-linked instruments.

A listed product tracking gold or another commodity may resemble an ETF in the way it trades, but may actually be an ETC, Exchange Traded Commodity.

Borsa Italiana clarifies that ETCs are not mutual funds: they are securities issued by a special-purpose vehicle, and their legal structure differs from that of ETFs.

This means the word ETF should not automatically be used for every listed product tracking an index or commodity.

Understanding an instrument’s legal structure is particularly important when analysing issuer risk, guarantees and tax treatment.

What happens if the company managing the ETF fails?

This is one of the most frequent questions.

For ETFs constituted as funds or SICAVs, the fund’s assets are separate from those of the management company. Borsa Italiana emphasises that ETFs listed as mutual funds or SICAVs have assets segregated from the companies responsible for their management and administration.

This means the failure of the management company does not automatically amount to losing the ETF’s assets.

But take care: this does not protect against poor performance of the investments within the fund. If the shares in the index lose 40%, the ETF can lose a similar percentage even if the manager is entirely sound.

It is therefore necessary to distinguish manager risk from risk in the underlying investments.

Accumulation and distribution

ETFs can also be distinguished by how they manage income.

In distributing ETFs, dividends or interest received by the fund are periodically paid to investors. In accumulating ETFs, income is instead reinvested within the fund.

Borsa Italiana notes that both approaches are possible and that income can either be distributed or incorporated into the ETF’s assets.

Economically, this does not mean either automatically generates a higher return than the other. What mainly changes is how income is managed, with possible tax and planning consequences.

An investor seeking to build capital might prefer automatic reinvestment. Someone interested in receiving regular cash flows might instead consider distribution. The choice therefore depends on the objective.

The index is probably more important than the ETF

When comparing two ETFs, attention often goes straight to the TER: 0.10% versus 0.20%, for example.

But a 0.10% difference in fees can be far less important than choosing between two completely different benchmarks.

An ETF tracking a global index and one tracking an American technology index can have almost identical costs, but radically different exposures and risks.

Before even asking “which ETF?”, it would therefore be more rational to ask:

“Which market do I want exposure to?”

Only afterwards does it make sense to compare instruments tracking that market based on costs, size, replication, liquidity and tracking error.

How to examine an ETF before buying it

The essential document is the KID, Key Information Document, containing the product’s key information. Before investing, it is useful to read at least the KID and the fund’s official documentation, checking the index tracked, risk, costs, replication method and income policy.

It is also useful to examine the actual portfolio. A few minutes spent checking its largest holdings, main countries and sectors can reveal exposures that the ETF’s name alone does not make apparent.

A basic analysis should therefore cover:

benchmark → composition → concentration → replication → costs → currency → liquidity → income policy.

You do not need to know every company in an index with thousands of constituents, but you do need to know what kind of risk you are buying.

The real advantage of ETFs

After listing all these risks, one might get the impression that ETFs are excessively complex instruments. In reality, one reason for their popularity is precisely their ability to provide exposure to very broad portfolios through a single instrument, with generally low costs and substantial transparency.

The advantage, however, does not come from the ETF label itself.

It comes from being able to choose an adequately diversified index, track it at low cost and keep the investment consistent with your time horizon.

An ETF used poorly does not become a good investment simply because it is cheap. Similarly, a portfolio comprising many ETFs is not necessarily more sophisticated or more diversified than one built with a few instruments.

Conclusion

ETFs are extremely useful instruments, but their operational simplicity can create an illusion: just press “buy” and immediately obtain a well-constructed portfolio.

In reality, ETF is merely the instrument’s form. What actually determines its risk is what the fund contains.

An ETF can be global or concentrated, equity-based or bond-based, physical or synthetic, exposed to one currency or many, extremely liquid or much less frequently traded. It can contain thousands of securities or just a few dozen.

The fundamental question should therefore not be:

“Are ETFs safe?”

But:

“What risks does this particular ETF contain, and are they consistent with my objective and how long I can keep the capital invested?”

Diversification remains one of the most important tools for managing risk, but it does not arise automatically by buying something labelled ETF.

It comes from understanding what is actually inside.