Tracking error — what is it and why does it matter?

What is tracking error?

Tracking error is a measure of how much an ETF fund's performance differs from the performance of the index it's supposed to track. The lower the tracking error, the more faithfully the ETF replicates its benchmark.

Formally, it's the standard deviation of return differences between the fund and the index over a given period.

Quick Answer

Tracking error measures how much an ETF's performance deviates from the index it tracks, defined formally as the standard deviation of return differences between fund and benchmark over a period — the lower it is, the more faithfully the ETF replicates. It differs from tracking difference, the total return gap in a period. Key drivers include management fees (TER), transaction costs, replication method, cash drag, withholding tax and securities lending. Broad-index UCITS ETFs typically show 0.01–0.15% annually. This is educational information, not investment advice.

---

Tracking error vs tracking difference

These two concepts are often confused:

• Tracking difference — the total difference in returns between ETF and index in a given period (e.g., "ETF earned 9.8%, index 10.0% → tracking difference = -0.2%").
• Tracking error — the variability of this difference over time (whether the deviation is stable or jumps).

For a long-term investor, tracking difference is more important — it shows the real cost of holding an ETF.

What affects tracking error?

1. Management fees (TER) — the biggest component. ETF with 0.20% TER will have tracking difference around -0.20%.
2. Transaction costs — portfolio rebalancing costs money.
3. Replication method — synthetic (swap) ETFs usually have lower tracking error than physical ones.
4. Cash drag — the fund holds some assets in cash (for payouts), which doesn't earn.
5. Withholding tax on dividends — depending on the fund's domicile.
6. Securities lending — lending securities generates additional income, which reduces tracking difference.

Typical values

How to check?

• justETF.com — comparison of tracking difference for hundreds of ETFs.
• Fund factsheet — "Performance" section compares ETF with benchmark.
• KID — the document contains information about costs, which directly affect tracking.

How can Freenance help?

Freenance allows you to compare the actual performance of your ETFs with benchmarks. You can see if your fund is losing on replication — and how much it costs you in PLN.

👉 Compare your ETF performance — freenance.io

FAQ

Is a low tracking error always better?

Generally yes for a passive investor, because the goal is to mirror the benchmark as closely as possible. However, a very low tracking error combined with a meaningfully negative tracking difference can still mean the fund consistently underperforms — so both metrics should be checked together.

What is the typical tracking error for a large UCITS ETF?

For broad, liquid indices such as the S&P 500 or MSCI World, well-managed UCITS ETFs usually report annual tracking error in the range of roughly 0.01% to 0.15%. Funds tracking smaller or less liquid markets tend to show higher values.

Does the replication method affect tracking error?

Yes — synthetic (swap-based) ETFs often report lower tracking error because the swap counterparty contractually delivers the index return, while physical ETFs are exposed to sampling, rebalancing and dividend timing. Each method has its own risk trade-offs that the KID document describes.

Where can I find the tracking error of a specific ETF?

The clearest source is the fund's factsheet or annual report, which usually publishes both tracking error and tracking difference. Independent comparison sites such as justETF also aggregate these figures across many UCITS ETFs.

How does tracking error relate to TER?

TER (the ongoing management fee) is one of the main drivers of tracking difference, and indirectly influences tracking error. A higher TER mechanically widens the gap between the ETF and its index, even if the manager replicates perfectly otherwise.

Related Articles

• ETF syntetyczny — czym się różni od fizycznego?
• Jak sprawdzić opłaty w funduszu inwestycyjnym — ukryte koszty, TER, opłaty manipulacyjne
• Sharpe Ratio — co to jest współczynnik Sharpe'a?