Should I invest in international stocks?
In one paragraph
International diversification reduces concentration risk in any single economy and provides exposure to faster-growing markets, but the appropriate allocation is genuinely debated — the case for some international exposure is strong; the exact percentage is a judgment call.
What this actually means
The debate over international allocation is one of the few genuinely contested questions in passive investing. Both sides have credible evidence and principled arguments.
The case for international exposure starts with geography. U.S. stocks represent roughly 60% of global market capitalization. An investor who holds only domestic equities is implicitly betting that the U.S. will continue to produce superior returns relative to the rest of the world — a bet that is uncompensated and concentrated. Historically, no single country has dominated global returns permanently. Japan led in the 1980s. Emerging markets surged in the 2000s. U.S. large caps dominated the 2010s. Holding a global portfolio captures whatever region is performing without requiring a prediction.
International stocks also provide exposure to different economic cycles, currencies, sector compositions, and valuation regimes. When U.S. equities are richly valued by historical measures, international markets often trade at steeper discounts — providing a natural rebalancing dynamic.
The case against heavy international exposure — or any — rests on U.S. multinationals. The S&P 500 already generates roughly 40% of its revenues outside the United States. Investors in Apple, Microsoft, or Procter & Gamble already hold international exposure through those companies' global operations. Explicitly adding an international fund may therefore double-count some diversification benefit.
Currency risk is a real complication. International investments fluctuate in value not just because foreign share prices move, but because exchange rates move. Over long periods, currency effects tend to wash out. Over shorter periods, they add volatility.
Most evidence-based portfolios recommend somewhere between 20% and 40% international allocation for equity investors. Stocks for the Long Run by Jeremy Siegel provides historical data on global equity returns across multiple countries and periods. The Elements of Investing makes the case for global diversification in plain terms.