What it means
The bias is measured by comparing what an investor actually holds at home with what a global market-weighted index would hold in that same country. If a country accounts for 4% of world stock market value and an investor puts 70% of their portfolio there, the gap of 66 percentage points is the home country bias.
The gap exists almost everywhere, and it is largest in countries with small domestic markets. Several forces feed it.
Familiarity is the biggest: people trust the companies whose products they buy and whose news they read, and unfamiliar foreign names feel riskier than they are. Currency worries, withholding taxes, higher foreign dealing costs and pension rules that favour domestic assets all add to the pull.
In a business context the same bias shows up beyond the investment portfolio. Founders often hold company shares, a house and a pension all tied to one economy, so a domestic downturn hits their salary, their property and their savings at the same time.
Treasury teams do the same thing when they park surplus cash entirely in home-currency deposits. Home country bias is not always irrational.
Matching assets to the currency of future spending is sensible for someone who will retire and spend at home, and domestic holdings avoid currency conversion costs and foreign tax paperwork. The problem is that most portfolios sit far beyond the level any of those arguments would support.
Fixing it is usually a matter of setting a deliberate target rather than reacting to headlines. Many investors adopt a global weighting and then tilt back towards home by a stated amount, so the tilt becomes a conscious decision with a number attached rather than an accident of habit.
In practice
Real-world examples.
Example
A manufacturing business owner in a small European country holds 85% of her personal pension in domestic industrial shares because she understands the sector. When a regional recession hits, order books at her own firm and the value of her pension fall in the same quarter, leaving her with no cushion.
Example
A corporate treasurer keeps all $12,000,000 of surplus cash in home-currency term deposits even though 60% of the company's costs are paid in another currency. A 15% currency move increases those costs while the deposits stay flat, and the board asks why no hedging or currency spread existed.
Example
An advisory firm reviews a client portfolio and finds a 78% domestic weighting against a 3% index weight. The adviser proposes moving to 40% domestic over four quarters, which keeps a deliberate home tilt while removing most of the single-country exposure.
Formula
Calculation
Home country bias = domestic allocation % - home market share of the global index %
A relative measure is also useful: overweight multiple = domestic allocation % / home market share %
An investor holds a $500,000 portfolio, of which $350,000 is in domestic shares.
Domestic allocation = $350,000 / $500,000 = 70%
Home market share of the global equity index = 4%
Home country bias = 70% - 4% = 66 percentage points
Overweight multiple = 70% / 4% = 17.5 times the neutral weight
To see the effect, assume the domestic market falls 30% in a year while the rest of the world is flat. The biased portfolio loses 70% x 30% = 21% of its value, or $105,000. A globally weighted portfolio with only 4% at home loses 4% x 30% = 1.2%, or $6,000. The difference of $99,000 is the price of the concentration in that single year.Case study
Seen in the real world.
The following is a fictional illustration. Kettleby Print Group, an invented family printing business, ran a small defined contribution pension scheme in which 92% of assets sat in domestic listed equities. Trustees liked the arrangement because members could name every holding, and the domestic market had performed well for six straight years.
A downturn in the domestic economy then cut the index by 28% over eighteen months while global markets outside that country were broadly flat. Members within three years of retirement saw balances fall by roughly a quarter, and several delayed retirement. A review showed that a 30% domestic weighting would have limited the fall to about 8%.
The trustees rewrote the default fund with a global weighting and a stated domestic tilt of 25%, documented in the investment policy. The illustrative point is that nobody had ever chosen 92%; it had simply accumulated through familiarity and inertia.
Watch out
Common mistakes.
- Confusing a domestic listing with domestic exposure. A large exporter listed at home may earn most of its revenue abroad, so the geographic risk sits somewhere other than the stock exchange.
- Treating any home tilt as an error. A modest, deliberate tilt can be justified by spending currency and tax treatment; the issue is size, not existence.
- Assuming currency hedging removes the need to diversify. Hedging addresses exchange rate movement, not concentration in one country's economy and its listed companies.
Questions
People also ask.
How large is home country bias in practice?
It varies, but domestic weightings of 50% to 90% are common even in countries representing only a few per cent of global market value.
Does buying global funds solve it?
Largely yes, provided the fund is genuinely market-weighted rather than a domestic fund with a handful of foreign names attached.
Is home country bias only about shares?
No, it appears in bonds, property and cash deposits, and it is often strongest in the property a household already owns.
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