Trading term
What is Home bias?
Home bias is holding far more of your own country's market than its share of the world market would suggest. It's the most common form of accidental concentration, and it's usually never been decided on.
Investors everywhere hold more of home than the world's numbers imply. It happens for reasons that all sound sensible on their own: the companies are familiar, the news covers them, the currency is the one you spend, and domestic accounts or tax treatment can favour them. None of those is a bad reason. They just don't add up to a plan.
The case against home bias isn't that it costs you return. Over the published windows, one large single-country index actually returned more than the global index — about 11.6% and 15.1% a year against the global 8.9% and 12.9%. It did fall harder in the bad year: in 2022, the worst calendar year in each series, the single-country index returned −19.46% against the global index's −17.96%. That's about a point and a half, which is worth knowing and isn't the argument. The argument is concentration. Home bias puts an outsized share of your money on one country's political, currency and economic outcome, and you can't know in advance which country that pays off for.
A global fund isn't the opposite of a home bet either. It's a diluted version of one. Index funds weight by company size, and as of July 2026 a single country made up 63.6% of the MSCI ACWI world index — so even a worldwide fund puts most of its money in that one market. That's the point of knowing the figure: what you own should be a number you've looked at, not a side effect of what felt familiar.
For example
Your stock money is 80% in home-market funds and 20% in a global fund. But that global fund is 63.6% weighted to the largest single market, so if that market is also your home one, your real home exposure is closer to 93% than 80%.
Go hands-on in Premium
That's Home bias in theory — it clicks when you read it on a live chart. Practise it hands-on in the TradeWize Premium Trading Psychology & Risk track.
Explore Premium →Why it matters to you
Home bias is concentration that doesn't look like concentration. Every holding is a broad, sensible-looking fund, and the account can still be a single-country wager. The check costs nothing: add up what share of your stock money tracks one country, compare it with that country's weight in the world index, and see whether the gap is one you'd have chosen.
⚠ The currency argument defends some of it, not all of it
There's a real point buried in home bias: you spend in your home currency, so home assets don't add exchange-rate swings on top of market swings. That argument genuinely supports holding more of home than its index weight, which is why world weights are rarely treated as the target. What it doesn't stretch to is 90% of everything you own, and it says nothing at all about the political and economic risk of one country.