If you built your portfolio from ETFs you recognised — the ones your broker's app puts first, the ones in the news — there is a good chance your equity allocation is more concentrated in your home market than you would guess. This is not really a mistake. It is a default, and defaults are how most portfolios actually get built.
Home-country bias is the tendency to hold more of your own market than its share of the global economy would suggest. A US investor holding almost entirely US equities and a French investor holding mostly CAC 40 names are doing the same thing, even though neither portfolio looks risky on its own terms.
The word "bias" is doing real work here. It is not a claim that your home market will underperform — nobody knows that. It is a claim about concentration: you are taking on country-specific risk (one economy, one currency, one regulatory regime, one political cycle) without having decided to, and usually without being paid extra for it.
The usual explanation is familiarity, and that is part of it. But the more interesting reason is that broad-market funds hide their geography behind generic names.
A fund called "World" or "Global" is typically weighted by market capitalisation, which means it holds each company in proportion to its size. That is a reasonable rule, but it has a consequence people rarely think through: the country with the largest listed companies dominates the fund. A market-cap world index is not evenly spread across the world, and it was never meant to be.
So you can hold a "global" fund and still be heavily concentrated in one country. Look up the current country breakdown on the index or fund factsheet before you assume otherwise — it is a published figure, it moves over time, and the number in your head is probably out of date.
The method matters more than any headline number, because the answer is specific to what you hold. Four steps:
1. Identify each holding by its ISIN, not by its name or ticker. The same fund is listed on several exchanges under different tickers, so matching on names is how people accidentally count one position twice.
2. Pull the country breakdown for each fund from its factsheet or KIID — the full list, not the top ten holdings. The top ten tells you about individual companies; it tells you almost nothing about geography.
3. Weight each breakdown by what you actually hold, then add them up. A fund that is 5% of your portfolio contributes 5% of its country weights, not 100%.
4. Compare the total against a deliberate target — one you chose, whether that is global market weights or something you have a reason to prefer.
Step four is the one people skip, and it is the one that turns this from trivia into a decision. "More than I expected" is not a finding you can act on. "More than I decided I wanted" is.
Assuming you find a gap you want to close, none of the fixes require rebuilding the portfolio.
Add rather than replace. A single ex-home-market fund, sized to close the gap, is usually enough. Selling to rebalance can trigger tax and transaction costs that the correction does not justify; directing new contributions at the underweight region gets you there more cheaply, just more slowly.
Check overlap before you buy, not after. Before adding a fund, look at whether it duplicates what you already hold. Two funds with different names and a largely shared set of underlying companies will not diversify you, whatever the marketing says.
Re-check on the schedule you already use. Geographic mix drifts exactly the way asset allocation drifts — quietly, as some markets outrun others. If you already review your allocation once or twice a year, add this to that review rather than making it a separate habit you will not keep.