TER vs tracking difference: how to estimate “real cost” (one example)
If you pick ETFs by TER alone, you can get surprised. TER is the fund’s published annual fee. Tracking difference is the actual gap between the ETF and its index over time. Tracking difference is what you really feel in returns — and it can be better or worse than TER suggests.
Two terms that sound similar (but aren’t)
TER (Total Expense Ratio)
TER is the ongoing fund fee (a percentage per year) that covers management and operating costs. It’s easy to compare across products — but it’s not the whole story.
Tracking difference
Tracking difference is the ETF’s return minus the index return over a period (often 1, 3, 5 years). If the index returns 10% and the ETF returns 9.8%, tracking difference is -0.2% for that period.
This is different from tracking error, which is about variability (how “wiggly” the gap is), not the average gap.
Why tracking difference can be smaller than TER (or even positive)
- Securities lending revenue: the fund earns income lending shares and can offset part of TER.
- Index implementation: sampling/optimization can reduce some trading costs (or increase them if done poorly).
- Withholding taxes on dividends: can create a persistent drag versus a gross index (this is often the biggest gap in equity ETFs).
- Cash drag and rebalancing: small frictions around index changes.
- Currency and timing effects: especially around dividend reinvestment and corporate actions.
One worked example (how to estimate “real cost”)
Assume an equity UCITS ETF has a published TER of 0.20%/year. Over the last 3 years, you look up performance and see:
- Index annualized return: 8.00%
- ETF annualized return: 7.75%
Then the annualized tracking difference is roughly:
7.75% − 8.00% = −0.25%/year
Interpretation: the ETF lagged the index by about 0.25% per year. If TER is 0.20%, the extra ~0.05%/year is likely other frictions (tax drag, trading costs, replication choices, timing).
A simple rule-of-thumb for comparing similar ETFs
- Use the same index (or very close) and the same currency hedging (if any).
- Compare tracking difference over multiple years if available.
- Treat tracking difference as your “real cost estimate” (net of everything) — then check if it’s stable.
Two common beginner traps
1) Comparing to the wrong index version
Indexes can be quoted as price, net return, or gross return. An ETF may naturally lag a gross index because real investors pay withholding taxes on dividends.
2) Ignoring trading costs you personally pay
TER and tracking difference are fund-level. Your personal “all-in” cost also includes bid/ask spread and broker commissions (usually small, but meaningful for frequent small trades).
Key takeaways
- TER is the label. Tracking difference is the reality.
- A reasonable “real cost” estimate is the ETF’s multi-year tracking difference versus the right index version.
- When two ETFs track the same index, the one with better tracking difference is usually the better implementation — even if TER is slightly higher.
Educational only, not investment advice.