How to Pick an ETF: The Four Checks Institutions Run
The expense ratio is the promised cost, not the delivered one. Four checks a professional runs before buying a fund — and the one that costs Europeans the most.
How to Pick the Best ETFs: The 4-Step Banker Audit
Prefer to watch? This article is the written companion to the video above.
Most people choose an ETF by looking at one number: the expense ratio.
That number is the cost the fund promises.
It is not the cost the fund delivers — and the gap between the two is where the interesting part is.
Here are the four checks a professional actually runs, and the reason none of them is the fee.
First, though: ETFs were not built for you
This matters, because it explains why the product behaves the way it does.
19 October 1987. Black Monday. The Dow falls over 22% in a single day.
What the crash exposed was not merely panic. It was a structural failure: when large funds tried to sell, the market seized, because there was no way to trade an entire basket of shares at once without crushing the price of every individual company in it.
The regulator wanted a “market basket” — a liquidity valve. In 1993, State Street launched SPY, the first US ETF. It still exists, and it remains the largest and most heavily traded fund in the world.
The ETF was institutional plumbing. You were not the customer. You are the beneficiary — which is a much better position to be in than most retail products offer, and it is worth understanding why.
The machine underneath: creation and redemption
You see a ticker. The professional market sees a process.
When a pension fund wants to put $100 million into an ETF, an authorised participant — typically a large investment bank — buys the actual underlying shares and swaps them in kind for ETF shares.
No cash changes hands between the fund and the bank.
That single design decision is why an ETF avoids most of the transaction costs and, in the US, the tax drag that bleeds a traditional mutual fund. When a mutual fund has to sell shares to meet redemptions, it realises capital gains — and it distributes them to you, whether you sold anything or not.
The ETF simply hands the shares back.
You are riding on a machine built for institutions, and you inherited its efficiency by accident.
And this is why the stock-picking argument is over
Before the checks, the reason you are doing this at all.
According to S&P Dow Jones Indices’ SPIVA scorecard for year-end 2025:
- 79% of active large-cap US equity funds underperformed the S&P 500 in 2025
- Over ten years, fewer than one in six beat it
- Over twenty years, roughly 92% of domestic US funds underperformed their benchmarks
These are not amateurs. They have Bloomberg terminals, research teams, direct access to company management, and their careers depend on winning.
Most of them lose to the average.
If the professionals cannot reliably win the stock-picking game, the rational move for an individual is not to play it harder. It is to stop playing and own the whole market through the most efficient infrastructure available.
Which brings us to choosing the right one.
Check 1 — Size. Below €500m, ask why.
Institutions are generally wary of funds below roughly €500 million. Below €100 million, a fund is often simply not profitable for the provider to operate.
That is not snobbery. It is closure risk.
Unprofitable funds get shut down. When a fund closes, you are forced to sell on someone else’s schedule — which can crystallise a tax bill you never planned for, in a year you did not choose.
A tiny fund with a headline-grabbing fee is sometimes a fund that will not exist in four years. The cheap fee was never the point.
Check 2 — Tracking difference, not TER. This is the one.
The TER is the promised cost. The tracking difference is the delivered cost.
Tracking difference is simply: the fund’s return minus the index’s return.
That is the number that actually determined your wealth. Everything else is marketing.
And here is the part that surprises people: the tracking difference can be negative. The fund can beat its own index.
How? Because funds earn revenue by lending their shares to short sellers. If a fund charges 0.10% in fees but earns 0.20% from securities lending, then your real, delivered cost is minus 0.10%.
You were paid to own it.
Two funds with identical TERs can have materially different tracking differences, year after year, and the cheaper-looking one is frequently the more expensive one.
Where to look: the fund’s annual report, or comparison platforms like justETF and Morningstar, which publish tracking difference by calendar year.
How to read it: look at several years, not one. You are looking for a small, stable, predictable gap. Not a good year.
Check 3 — Liquidity is not what is on your screen
Stop looking at the ETF’s daily trading volume.
Volume tells you what has traded. It does not tell you what can trade.
An ETF’s true liquidity is the liquidity of the things it holds. A fund tracking the S&P 500 is backed by the tradability of the 500 largest companies in America. That is an ocean.
As long as the fund is large enough for authorised participants to be willing to create and redeem shares, you will get a fair price — no matter how quiet the ticker looks on a Tuesday afternoon.
A thinly traded ETF holding highly liquid shares is fine. A heavily traded ETF holding illiquid junk is not. The screen tells you nothing about which is which.
Check 4 — Physical, for anything you intend to keep
For your core, long-term holdings: physical replication.
A physical ETF owns the actual shares. A synthetic ETF holds a derivative contract with a bank, which promises to deliver the index return — which means you are exposed to that bank’s ability to pay.
To be fair to synthetic funds, and this deserves saying plainly: in Europe, UCITS caps counterparty exposure at 10% of fund value, collateral is marked to market daily, and most providers keep net exposure close to zero. Synthetic ETFs came through 2008, 2020 and 2022 without incident. They have genuine advantages in certain markets and tax structures.
But close to zero is not zero — and there is no reason to carry a bank’s credit risk in the position you plan to hold for thirty years. The mechanics of that risk, and where it came from, are worth understanding properly.
Physical for the core. Synthetic only where it earns its place.
The check that is worth more than all four: your fund’s domicile
If you are a European investor buying US equity exposure, this single line is probably costing or saving you more than every fee decision you will ever make.
First, why you cannot buy the American funds at all.
Try to buy VOO — Vanguard’s US-listed S&P 500 ETF — from Germany or the UK, and your broker will refuse. This is not a judgement on the fund. Under the EU’s PRIIPs regulation, a product may only be sold to EU retail investors if a Key Information Document exists, and US providers generally do not produce one.
It is a paperwork mismatch. So you must use a UCITS version — and UCITS funds are typically domiciled in either Ireland or Luxembourg.
This is where it gets expensive.
The United States levies withholding tax on dividends paid to foreign funds:
| Fund domicile | US withholding tax on US dividends |
|---|---|
| Ireland (ISIN begins IE) | 15% — under the US–Ireland tax treaty |
| Luxembourg (ISIN begins LU) | 30% |
Fifteen percentage points. On every dividend. Every year. Compounding for as long as you hold the fund.
It does not appear in the TER. It does not appear in the fund name. It appears nowhere a normal person would think to look — and it is quietly larger than almost any fee you could negotiate.
The check takes five seconds: look at the ISIN. IE at the front, or LU.
Most European investors have never been told to do this. It is, by a wide margin, the highest-value thirty seconds in this entire article.
A German footnote: the Vorabpauschale
For German investors: the Vorabpauschale — an advance lump-sum tax on notionally accrued fund gains, charged each January and derived from an official base rate — effectively vanished when rates were at zero. With rates positive, it is back.
It is a real drag, but a modest one, and it is prepaid: it is credited against your eventual capital gains tax rather than lost.
German fund taxation is genuinely intricate, and this is a description rather than tax advice. It is worth an hour with a Steuerberater — which is one of the few hours in personal finance that reliably pays for itself.
The protocol, in one place
Before you buy anything:
- Size — under roughly €500m, ask why. Under €100m, assume closure risk.
- Tracking difference — not the TER. Several years of it. Small, stable, predictable.
- Liquidity — of the holdings, not of the ticker.
- Physical replication — for anything you intend to keep.
- Domicile —
IE, notLU, for US exposure. This one is not optional.
None of these are difficult. All of them take less time than reading a single fund’s marketing brochure.
In 2026, boring is beautiful. The infrastructure was built by institutions to solve institutional problems, and it works. Your only genuine edge is that you are allowed to be patient, and they are not.
Educational content only — not investment advice, and not a personal recommendation. Speak to a qualified, licensed professional before acting.
Primary sources
- 01SPIVA U.S. Scorecard — Year-End 2025 — S&P Dow Jones Indices
- 02SPIVA U.S. Scorecard — overview and archive — S&P Dow Jones Indices
- 03Regulation (EU) No 1286/2014 (PRIIPs) — Key Information Document requirement — EUR-Lex / Official Journal of the European Union
- 04Convention between the Government of the United States of America and the Government of Ireland for the avoidance of double taxation (Article 10, Dividends) — U.S. Department of the Treasury
Questions people actually ask
What is the difference between TER and tracking difference?
The TER — total expense ratio — is the cost the fund tells you it will charge. The tracking difference is the fund's actual return minus the index's actual return: the cost it genuinely delivered. They are frequently not the same number, and the second one is the only one that ever touched your money. A fund can even have a negative tracking difference — beating its index — because it earns revenue lending its shares to short sellers, and that revenue can exceed the fee.
Where do I find the tracking difference?
In the fund's annual report or factsheet, and on comparison platforms such as justETF or Morningstar, which publish it per calendar year. Look at several years, not one: a single year can flatter or damn a fund for reasons that have nothing to do with how it is run. What you want to see is a small, stable, predictable gap — not a good year.
How large should an ETF be before I buy it?
As a working rule, institutions are wary below roughly €500 million, and a fund under €100 million is often simply unprofitable for the provider to run. That matters to you because unprofitable funds get closed. When a fund closes you are forced to sell on someone else's timetable — which can crystallise a tax bill you did not plan for and had no reason to expect. That is closure risk, and it is the risk that a low headline fee is sometimes hiding.
Does an ETF's daily trading volume tell me how liquid it is?
No, and this is one of the most persistent misunderstandings in retail investing. On-screen volume tells you what has traded, not what can trade. An ETF's real liquidity is the liquidity of the securities it holds: a fund tracking the S&P 500 is backed by the tradability of the 500 largest companies in America. As long as the fund is large enough that authorised participants are willing to create and redeem shares, you will get a fair price — regardless of how quiet the ticker looks.
Should I choose physical or synthetic replication?
For a core, long-term holding, prefer physical. A physical ETF owns the actual shares; a synthetic one holds a derivative contract with a bank and is therefore exposed to that bank's ability to pay. In Europe, UCITS rules cap that exposure at 10% of fund value and collateral is marked daily, so it is a managed risk rather than a hidden one — but it is not zero, and there is no reason to carry it in the position you intend to hold for thirty years.
Why can't I buy VOO or QQQ from Europe?
Because of a disclosure rule, not a trading restriction. Under the EU's PRIIPs regulation, a product may only be sold to retail investors in the EU if a Key Information Document is available. US providers generally do not produce one, so European brokers block the purchase. This is not a judgement about the funds. It is a paperwork mismatch — and the practical consequence is that you must use UCITS versions, which are typically domiciled in Ireland or Luxembourg.
Why does an ETF's domicile matter so much?
Because of withholding tax on US dividends, and this is where most European investors quietly lose the most money. A fund domiciled in Ireland benefits from the US–Ireland tax treaty and suffers 15% US withholding tax on dividends from US shares. A comparable fund domiciled in Luxembourg generally suffers 30%. That 15-point difference applies to every dividend, every year, and compounds for as long as you hold. It is invisible in the TER, invisible in the fund name, and larger than almost any fee you will ever save.
How do I check where a fund is domiciled?
The ISIN. If it begins with IE, the fund is Irish-domiciled; LU means Luxembourg. It is printed on every factsheet and shown in every broker search. This is a five-second check that most European investors have never been told to make, and for a US-equity holding it is worth more than any amount of time spent comparing expense ratios.
What is the Vorabpauschale?
A German advance lump-sum tax on notionally accrued gains in funds, charged in January and calculated from an official base rate. When rates were at zero it effectively vanished; with rates positive it is back. It is a genuine drag but a modest one relative to the domicile question — and it is prepaid, meaning it is credited against your eventual capital gains tax rather than lost. This is a description, not tax advice: German fund taxation is genuinely intricate and worth an hour with a Steuerberater.
Why should I buy an index fund rather than pick stocks?
Because the evidence on professional stock pickers is brutal, and they are trying harder than you are. In 2025, 79% of active large-cap US equity funds underperformed the S&P 500, according to S&P Dow Jones Indices' SPIVA scorecard. Over ten years, fewer than one in six beat it. Over twenty years, roughly 92% of domestic US funds underperformed their benchmarks. These are people with Bloomberg terminals, research teams and every informational advantage available — and most of them lose to the average.
Were ETFs designed for retail investors?
No, and it explains a great deal about how they behave. The first US ETF, SPY, was launched in 1993 by State Street after the 1987 crash exposed a structural problem: there was no way for large institutions to trade an entire basket of shares at once without moving the price of every individual name. The ETF was built as an institutional liquidity valve. Retail access was a consequence, not the design goal. You are a passenger on institutional infrastructure — which, on the whole, is an extremely good place to be.