Home bias

Home bias is the tendency for investors to concentrate their portfolios heavily in companies from their own country, holding far more domestic stock exposure than a globally diversified portfolio would actually suggest. A US investor might hold ninety percent or more of their equity portfolio in US stocks even though the US represents a much smaller share of the total global stock market.

The bias comes from familiarity. Investors naturally feel more comfortable with companies whose products they use, whose news they follow in their own language, and whose economic environment they understand firsthand, compared with companies operating in unfamiliar markets under different regulations, currencies, and accounting standards. That comfort does not necessarily translate into better returns, it just makes domestic stocks feel like the safer, more knowable choice.

Home bias reduces diversification, since a portfolio concentrated in one country is exposed to that country's economic cycles, currency, and market conditions all at once. Investors who deliberately hold international stocks or funds alongside domestic ones are working directly against this bias, trading some of that comfort and familiarity for broader diversification across economies that do not all move in sync.