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Geographic Diversification and Home Bias

Most investors over-concentrate in their home market. Global diversification can reduce risk, but the debate over how much international exposure is enough has no single right answer.

Geographic Diversification and Home Bias

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What Is Home Bias?

  • The tendency for investors to overweight their domestic market relative to its global share
  • US investors hold roughly 70 to 80% domestic equity despite the US being about 60% of world cap
  • Familiarity, perceived safety, and currency comfort all contribute to this persistent tilt
  • Home bias exists across nearly every country and is not unique to US investors

Full Guide

What Is Home Bias?

  • The tendency for investors to overweight their domestic market relative to its global share
  • US investors hold roughly 70 to 80% domestic equity despite the US being about 60% of world cap
  • Familiarity, perceived safety, and currency comfort all contribute to this persistent tilt
  • Home bias exists across nearly every country and is not unique to US investors

US vs. International Performance Cycles

  • US stocks significantly outperformed international markets from roughly 2010 through 2024
  • International stocks outperformed the US during the 2000 to 2009 decade by a wide margin
  • Leadership rotates; past outperformance does not predict which region will lead next
  • Recency bias causes investors to favor whatever market has performed best recently

The Case for Global Diversification

  • International stocks reduce portfolio volatility because regional markets do not move in lockstep
  • Roughly 40% of global revenue and innovation originates outside the United States
  • Emerging markets offer exposure to faster GDP growth and expanding middle classes
  • Spreading risk globally captures the diversification benefit across economic cycles

The Case for a Domestic Tilt

  • US companies already generate significant international revenue; S&P 500 earns 40% abroad
  • The US has stronger shareholder protections, deeper capital markets, and greater transparency
  • Currency fluctuations can add volatility without a guaranteed long-term return premium
  • Some research suggests a moderate home bias is rational given lower domestic information costs

Currency Risk and Hedging

  • International returns include both asset returns and currency returns that can help or hurt
  • A weakening dollar boosts international returns; a strengthening dollar reduces them
  • Currency-hedged ETFs remove exchange rate exposure but add cost and may reduce diversification
  • Over long horizons, currency effects tend to wash out; hedging matters more short-term

How Much International Exposure Is Enough?

  • Market-cap weighting suggests roughly 40% international, but few advisors go that high
  • Common allocations range from 20 to 40% international equity depending on risk tolerance
  • A blend of developed and emerging markets provides exposure across the risk-return spectrum
  • The most important step is having meaningful international exposure rather than debating the amount

Implementation and Practical Considerations

  • Total international ETFs like VXUS offer broad exposure in a single fund
  • Global funds that include the US handle the domestic-international split automatically
  • Foreign tax credits on dividends can offset some tax cost of international holdings
  • A written investment plan helps maintain your target allocation through regional divergence