Here Are 6 ETF Metrics That Are Just As Important As Returns

Are there any ETF metrics that matter other than return? At the end of the day, investors may not care about much else other than return, but there are metrics that can give useful clues as to how ETFs might perform.

ETFs (short for Exchange Traded Funds) have never been more popular as an investment class. Low fees, instant diversification and simple access to global markets have made ETFs the default choice for many investors. But popularity has created a problem that too many investors jump into them just because of what they are called and/or because of what they track. Last week’s SpaceX IPO magnified this problem, where investors sought out ETFs just for exposure as they couldn’t own it directly even if they wanted to.

In our view, if you want to understand an ETF properly, you need to look beneath past performances and what it has exposure to. You need to understand how the ETF behaves, how it is constructed and how faithfully it delivers what it promises. That is where the real insight lies.

In our view, there are six metrics that matter far more than most investors realise. They are neither complicated nor obscure, but they are often ignored. And ignoring them can lead to surprises that have nothing to do with the market and everything to do with the ETF itself. Here are the six metrics that deserve your attention.

6 ETF Metrics That Are Just As Important As Returns

1. Tracking error: the truth about whether your ETF is doing its job

Almost ETF promises to track an index, it might be a well known one such as the ASX 200 or the S&P 500; but it could also be a more obscure one such as the Philadelphia Semiconductor Index or some global bond benchmark. Either way, the ETF’s job is to follow that index as closely as possible.

The tracking error tells you whether it is succeeding. It measures the difference between the ETF’s performance and the index it is meant to replicate. A low tracking error means the ETF is doing its job. A high tracking error means something is off.
Investors often assume that tracking error is only a problem for exotic ETFs, but such investors are wrong. Even broad‑market ETFs can drift if the fund uses sampling instead of full replication, if it holds more cash than expected or if it faces liquidity constraints in the underlying securities.

Tracking error also matters because it compounds. A small deviation each year can add up to a meaningful gap over a decade. Investors who think they are buying the index may discover they are not getting the index at all.
The irony is that tracking error is one of the simplest metrics to check. Yet it is one of the least discussed. If you want to know whether your ETF is delivering what it claims, start here.

2. Portfolio turnover: the hidden cost that eats into returns

Portfolio turnover tells you how often the ETF buys and sells securities. It sounds like a technical detail but is a cost. Every time an ETF trades, it incurs transaction costs. These costs are not included in the headline management fee but are are buried inside the fund’s performance. High turnover means higher costs and higher costs mean lower returns. Lower costs (compared to buying each stock individually) are why investors have turned to ETFs, but if your fund has a high turnover, you may be paying a premium price compared to what you’d be getting buying a handful of stocks individually.

Turnover also tells you something about the index itself. Indices have different frequencies of being rebalanced but the more frequent the rebalancing, the higher the turnover. This matters because turnover is not evenly distributed across ETFs. A broad‑market ETF might have turnover of less than 5%. A thematic ETF might have turnover of 50% or more. Two ETFs with similar names can have very different turnover profiles. The bottom line here is that you want to understand the true cost of an ETF, you need to understand how often it trades.

3. Yield: not just how much, but what kind

Yield is one of the most misunderstood ETF metrics. Investors often look at the headline number and assume it reflects income. Its true that sometimes it does, but other times it does not. ETF distributions can include interest, dividends, realised capital gains and, in some cases, return of capital. These components behave differently. They have different tax implications. And they tell you different things about the ETF’s underlying holdings.

A high yield can be a sign of strong income generation. It can also be a sign of forced capital‑gains distributions caused by index rebalancing. In some cases, it can be a sign that the ETF is returning your own capital to you.
Yield also varies across markets. Australian ETFs tend to have higher yields because of franking credits. US ETFs tend to have lower yields because companies prefer buybacks. Bond ETFs behave differently again.

The point is not that yield is unimportant. It is that yield needs context. You need to know what is driving it, whether it is sustainable and whether it aligns with your objectives. A high yield is not always a good yield. A low yield is not always a bad one. The composition matters more than the number.

4. Top‑10 holdings concentration: the silent driver of risk

Many investors buy ETFs for diversification. They assume that owning hundreds of stocks reduces risk. In theory, it does. In practice, it depends on concentration. The top‑10 holdings of an ETF often account for a large share of its risk. In some ETFs, the top 10 represent 20% of the portfolio. In others, they represent 50% or more. A global ETF might look diversified but still be dominated by a handful of mega‑caps.

This is important because concentration drives behaviour. If the top 10 are highly correlated, the ETF will behave like a concentrated portfolio even if it holds hundreds of names. If the top 10 are volatile, the ETF will be volatile. If the top 10 are expensive, the ETF inherits that valuation risk.

Concentration also varies across markets. The ASX is dominated by banks and miners whilst the US market is more diversified. Conversely, emerging markets are dominated by state‑owned enterprises. Investors who want diversification need to look beyond the number of holdings and the weight of the largest holdings. That is where the real risk sits.

5. Currency exposure: the invisible force behind your returns

Currency exposure is one of the most powerful drivers of ETF returns. It is also one of the least understood.
When you buy an unhedged international ETF, you are not just buying foreign equities or bonds. You are buying the currency exposure that comes with them. If the Australian dollar falls, your unhedged ETF rises. If the Australian dollar rises, your unhedged ETF falls.

This can dominate returns. In some years, currency movements have contributed more to ETF performance than the underlying market itself. Investors who think they are buying the S&P 500 may discover they are actually buying the AUD/USD exchange rate. Some ETFs are hedged and such funds remove this exposure. But hedging is not free – it introduces its own costs and complexities.

The choice between hedged and unhedged exposure is not trivial nor is it a clear cut case. The option right for you depends on your time horizon, your risk tolerance and your view on currency cycles. But the key point is that currency exposure is not optional. It is embedded in the ETF unless you choose otherwise. Ignoring currency exposure is one of the most common mistakes ETF investors make. But ironically, it is also one of the easiest to avoid.

6. Cash drag: the quiet performance killer

Cash drag is the portion of the ETF that sits in cash rather than in the market. Cash earns less than equities or bonds over time. If an ETF holds more cash than expected, its returns will lag the index. This lag can be small in a single year but meaningful over a decade.

Cash drag can occur for several reasons. The ETF may be receiving inflows and waiting to deploy them. It may be holding cash to manage redemptions. It may be using sampling rather than full replication. Or it may be holding cash because the underlying securities are illiquid.

The problem is that cash drag is rarely advertised – it is not part of the headline fee, nor part of the marketing material. It is buried in the ETF’s holdings. Investors who want to track an index need to know how much of their money is actually invested in that index. Cash drag is the difference between the ETF you think you own and the ETF you actually own.