How to analyse an ETF portfolio: learn to look through the wrapper

An ETF is a bag of hundreds of holdings. Until you look inside, you do not know what you own — or how many times you own it.

The ETF has one magnificent quality and one quiet flaw. The quality: for a few euros in fees, you own hundreds of companies at once. The flaw: the line on your statement stops telling you anything. “World ETF — €4,200” is an opaque line: it shows neither the countries, nor the sectors, nor the actual companies inside. Analysing an ETF portfolio therefore starts with learning to look through the wrapper — what professionals call look-through analysis.

Three ETFs are not three bets

The most common trap among ETF investors: believing that three lines make three different exposures. Take a very popular trio — a World ETF, an S&P 500 ETF, a Nasdaq ETF. Three funds, maybe three issuers, three lines on the statement. Now look inside: the same US mega-caps dominate all three indices. By stacking them you have not diversified — you have bought the same bet three times, and paid for it three times.

The phenomenon has a name: overlap. It is invisible at the line level and obvious at the exposure level. It is a close cousin of the trap we describe in our article on effective assets: counting your lines measures nothing — you have to measure what they contain and how they move together.

What to look at, in order

• Real geography. A “World” ETF is not spread evenly across the world: the US weight is in the region of 70% (a figure published by issuers and variable over time — your fund's factsheet is the authority). Owning “the world” very often means owning, two-thirds of it, America.
• Real sectors. Add up the technology inside each of your funds, plus your direct tech holdings: that total — not your line count — says whether your portfolio is a sector bet.
• Direct duplicates. Holding a stock directly AND an ETF that contains it means holding it twice. Neither good nor bad in itself — but you need to know, because the day that stock falls, both lines fall together.
• Correlations and effective assets. After the look-through, the final question remains: how many independent bets does this portfolio actually contain? Our preferred measures are detailed in the risk analysis article.

A tax wrapper is not an allocation

Every country has its favourite wrapper — France's PEA, the UK's ISA, America's 401(k) — and every country has the same confusion: mistaking the tax envelope for diversification. A wrapper is a set of tax rules and eligibility constraints. It says nothing about the quality of what you put inside it.

Constraints can even shape your exposure without you noticing. France's PEA, for instance, restricts eligibility to European stocks and European-equity funds — so a “full-PEA” investor often carries a heavy European tilt by accident rather than by choice, while synthetically replicated ETFs allow world or US exposure inside the same wrapper. Two identical-looking accounts can carry radically different exposures. The only way to know is, once again, to look through: the label on the box does not describe what is in the box.

The method, step by step

What OplynQ automates

Doing this by hand is possible — tedious the first time, discouraging at every update. OplynQ does it continuously: import your statements (all wrappers) or connect accounts read-only, and the cockpit computes your exposure by sector and region with full ETF look-through, plus correlations and effective assets on the merged portfolio. The AI copilot then answers the question this whole article prepares: “all told, what am I actually exposed to?”