International Investing

Roughly 40% of the world's stock market value sits outside the United States, and most American portfolios own almost none of it. This guide covers home bias, what developed and emerging markets actually are, how currency risk works, and how to think honestly about the US versus the world debate when neither side can prove its case.

By Karanvir Singh, founder of Quantix Invest

What international investing means

An international stock fund owns shares of companies domiciled outside your home country. For a US investor, "international" or "ex-US" means everything from Nestle and Toyota to Samsung, ASML, Shopify, Taiwan Semiconductor, and thousands of smaller businesses across roughly 45 countries.

The world stock market is usually cut three ways:

• US: around 60% to 65% of global market capitalization as of the mid 2020s, up from roughly 40% in the late 1980s.
• Developed ex-US: Japan, the UK, Canada, France, Germany, Switzerland, Australia, and similar. Roughly 25% to 30% of the world.
• Emerging markets: China, India, Taiwan, South Korea (classified as emerging by some index providers and developed by others), Brazil, Mexico, Saudi Arabia, South Africa and others. Roughly 10% of the world.

These weights move. In 1989, at the peak of Japan's asset bubble, Japan alone was about 45% of the world stock market by capitalization, larger than the United States. That fact is worth pausing on, because it is the strongest available evidence that today's weights are not permanent and that concentrating in whichever market is currently dominant has historically been an expensive habit.

Home bias: the default nobody chose

Home bias is the universal tendency to hold far more of your own country's stocks than its share of the world market would justify. It is not an American quirk. Japanese investors overweight Japan, Canadians overweight Canada (a market that is heavily banks and energy and about 3% of the world), Australians overweight Australia. Everywhere, in every era, investors overweight what is nearby.

Where does it come from?

• Familiarity. You know the companies, you use their products, you read their news. Familiarity feels like information. It usually is not.
• Recency. US stocks have beaten international stocks for most of the period from 2010 through the mid 2020s. Investors extrapolate whatever has been happening for the last decade and call it structure.
• Structural friction. Employer retirement plans often offer a strong domestic default and a weak or missing international option. Many people hold what the menu gave them.
• Currency and news discomfort. Foreign holdings introduce exchange rates and headlines about places you cannot easily assess.

There are two arguments for some deliberate home bias that are actually defensible. First, your liabilities are in your home currency: you will retire and buy groceries in dollars, so matching some of your assets to that currency reduces mismatch. Second, home funds are typically slightly cheaper and more tax-efficient to hold. Neither argument gets you to 100% domestic. They get you to "somewhat overweight home," which is roughly what thoughtful investors in every country end up doing.

The argument that does not hold up is "US companies earn a lot of revenue abroad, so I already have international exposure." It is true that a large share of S&P 500 revenue comes from outside the US. But revenue exposure is not the same as market exposure. Studies of return behavior consistently find that a stock's returns are driven far more by the country where it is listed and the sector it operates in than by where its customers are. In 2008, foreign revenue did not save US stocks. If it were true that multinational revenue provided international diversification, US and international indexes would not have diverged by tens of percentage points over the 2010s. They did.

Developed versus emerging markets

Developed markets have mature institutions: deep and liquid exchanges, strong shareholder protections, reliable accounting standards, independent courts, freely convertible currencies, and stable politics by global standards. Japan, Western Europe, the UK, Canada, Australia, Singapore, Hong Kong. These markets look and behave a great deal like the US market, which is both their virtue (they are boring and reliable) and their limitation (they correlate with the US fairly highly, especially in crises).

Emerging markets are economies growing into that status. Higher growth potential, and correspondingly more of everything that can go wrong: currency devaluations, capital controls, weaker accounting and enforcement, political interference in listed companies, and concentration risk. Emerging market indexes are also far less diversified than they appear: China, Taiwan, India, and South Korea together typically make up well over half the index, and a small number of very large technology companies dominate the top holdings.

Two persistent lessons from the emerging market record are worth carrying. The first is that GDP growth does not translate reliably into stock returns. This is one of the most robust and least intuitive findings in finance. Fast-growing economies fund that growth by issuing new shares, which dilutes existing shareholders, and investors bid prices up in advance so the growth is already in the price. Elroy Dimson, Paul Marsh, and Mike Staunton documented across more than a century of data that the cross-country correlation between real GDP per capita growth and real equity returns has been near zero or slightly negative. China from 2000 to the mid 2020s is the modern case study: extraordinary economic growth, unimpressive returns to foreign equity holders.

The second is that political risk in emerging markets is not theoretical. Russia's market was effectively written to zero for foreign investors in 2022 when sanctions and capital controls made positions untradeable. Index providers removed it. Investors did not get to sell. That is a category of risk that does not exist in the same form in developed markets, and it argues for holding emerging markets as a diversified slice rather than a concentrated bet.

Currency risk, and whether to hedge it

When you own a foreign stock, you own two things: the business, and the currency it is priced in. Your return in dollars is roughly the local return plus the change in that currency against the dollar.

A weakening dollar boosts your international returns when translated back. A strengthening dollar drags them down. In the 2010s and early 2020s, the dollar was broadly strong, which accounted for a meaningful share of international underperformance measured in dollars. Much of the time, international stocks in local currency did considerably better than the dollar returns that US investors experienced. That is not a small footnote. It is one of the main reasons the "international is broken" narrative took hold.

Should you hedge the currency? The considered answer for long-horizon stock investors is usually no, or not much, for these reasons:

• Currency has no expected return. Over long periods, currency movements have been roughly a wash, oscillating rather than trending indefinitely. Hedging removes noise, not a negative drift.
• Hedging costs money. Forward contracts carry the interest rate differential between the two currencies plus implementation costs. It is not free.
• Unhedged foreign currency is a hedge against your own country's problems. If US inflation surges or the dollar falls sharply, unhedged foreign assets gain in dollar terms exactly when your domestic purchasing power is being eroded. This is a genuine and underrated benefit.
• Currency volatility is small relative to stock volatility. Adding currency risk to an already volatile asset does not raise total portfolio risk much, and it lowers correlation.

For international bonds the calculus reverses. Bond returns are small and steady, so currency swings can be larger than the entire return of the asset, swamping the reason you own bonds in the first place. This is why the standard recommendation is that international bonds, if held at all, should be currency-hedged back to your home currency. Vanguard's decision to hedge its international bond fund rests on exactly this reasoning: hedged foreign bonds have historically had volatility similar to domestic bonds while adding issuer diversification.

Worked example: the same stock, two currencies

You buy 100 shares of a European company at 50 euros per share. The exchange rate is 1.10 dollars per euro.

Cost: 100 x 50 = 5,000 euros = 5,000 x 1.10 = $5,500.

One year later the stock has risen 10% in local terms to 55 euros. Your holding is worth 5,500 euros. Now consider three currency outcomes.

Same company, same business performance, same 10% gain in euros, and your outcome ranges from losing 1% to gaining 21%. That spread is currency risk, and it is why international returns quoted in dollars can look so different from the same markets quoted locally.

Now extend it over a decade to see the scale of the effect. Suppose international stocks return 6% per year in local currency for ten years while the dollar strengthens by 2% per year against those currencies. Local growth: 1.06¹⁰ = 1.79, or plus 79%. Currency drag: 0.98¹⁰ = 0.817. Dollar result: 1.79 x 0.817 = 1.46, or plus 46%, about 3.9% annualized. A US investor looking at that decade concludes international stocks returned under 4% a year and are hopeless. A European investor holding the identical index saw 6% a year. Neither is wrong. They are measuring in different money.

This cuts both ways, which is precisely the point. A decade of dollar weakness would flip the arithmetic and produce international returns in dollars well above the local return. Currency effects mean-revert over long periods more than they trend, which is why long-horizon investors are generally advised to accept them rather than pay to remove them.

The US versus the world debate, handled honestly

This is the most contested allocation question in retail investing, and it deserves a fair statement of both cases rather than a slogan.

The case for holding little or no international.

• US markets have delivered higher returns than international markets over most of the period since 2010, by a very wide margin.
• The US has deeper capital markets, stronger shareholder rights, better enforcement, more innovation and entrepreneurship, better demographics than Europe or Japan, and dominance in the industries with the highest returns on capital.
• Large US companies earn substantial revenue abroad, so US investors get some economic exposure to global growth.
• US funds are cheaper and more tax-efficient for US investors, and there is no currency risk.
• Correlations between developed markets have risen over decades, which reduces the diversification benefit international was supposed to provide.

The case for holding international at or near market weight.

• Every one of the arguments above was equally available, and equally convincing, about Japan in 1989. Japanese investors who concluded that Japan's superior corporate management and growth justified concentration then endured a market that took over thirty years to reclaim its high.
• Past outperformance is not a forecast; it is often the mechanism by which future returns get lower. Much of the US advantage since 2010 came from valuation expansion, that is, investors paying more per dollar of earnings, not from superior earnings growth alone. Valuation expansion is a one-time gain that raises the price and lowers the expected future return.
• The valuation gap is large and persistent. Through much of the mid 2020s, US stocks traded at substantially higher price-to-earnings multiples than developed international markets, with the gap near the widest levels in decades. Starting valuations have historically been one of the few variables with real predictive power over ten-year returns, though the relationship is noisy and has been wrong for long stretches.
• The US is roughly 60% to 65% of world market cap. Holding 100% US is an active bet against the collective judgment of every investor on earth about the remaining third. The market-cap-weighted portfolio is the only one that requires no forecast.
• Correlations rising does not mean returns converge. Markets can move together day to day and still deliver dramatically different cumulative returns over a decade, which is exactly what happened in the 2000s and again in the 2010s in opposite directions.
• Single-country risk is real even for the US. Concentrated policy mistakes, regulatory shifts, or a decade of poor returns are possible in any country. Diversification is protection against the scenario you cannot foresee.

The honest resolution. Nobody knows which will win over your particular investing horizon. Both John Bogle (who argued US investors need no international exposure) and Vanguard's own research team (which recommends roughly market weight, typically implemented at 30% to 40% of equities) held defensible views. What is not defensible is deciding this question by looking at the last ten years of returns, because that is precisely the input most likely to be backwards.

Lost decades and why diversification is not free

Diversification only works if you hold the loser long enough for it to matter. That requires actually experiencing long periods of regret, which is the part investors underestimate.

2000 to 2009, the US lost decade. The S&P 500 delivered a slightly negative total return across those ten calendar years. International developed markets were modestly positive, and emerging markets were dramatically positive, compounding at roughly 10% per year over the period. An investor who held international during those ten years was rewarded substantially for it. At the end of that decade, articles asked whether US stocks were permanently broken.

2010 to the mid 2020s. The reverse. US stocks compounded at a high double-digit annualized rate for stretches while developed international lagged by a wide margin in dollar terms, and emerging markets delivered close to nothing over some multi-year windows. By the mid 2020s the accumulated gap was so large that a generation of investors had never seen international work.

Japan, 1989 to 2024. The Nikkei 225 peaked near 38,900 at the end of 1989 and did not durably exceed that level until 2024, a wait of roughly 34 years. A Japanese investor with 100% home bias had a career-length lost period. A Japanese investor at global market weight, with roughly 60% of equities in a rising US market, had an entirely ordinary retirement.

That last comparison is the clearest single argument in this guide. The purpose of international diversification is not to raise your expected return. It is to make sure that no single country's thirty-year misfortune becomes your thirty-year misfortune. You pay for that protection in the form of holding something that is usually underperforming something else, which feels like a mistake every year until the one decade when it is not.

How much international is reasonable

There is no single right answer, but the reasonable range is well bounded. Anything from about 20% to 40% of your stock allocation is a defensible position with real institutional support behind it.

Practical guidance that matters more than the exact number:

• Pick a number in the reasonable range and hold it through a full cycle. The worst outcome is not 20% versus 40%. It is drifting to 40% after international outperforms and cutting to 0% after it lags, which is buying high and selling low with extra steps.
• Emerging markets do not need a separate decision for most people. A total international index fund includes them at their market weight, roughly a quarter of the ex-US market. That is a sensible default. Adding a dedicated emerging fund on top is an active tilt.
• Rebalance mechanically. Holding a fixed international percentage forces you to buy whichever market has lagged, which is the discipline the whole structure is meant to provide.
• Write down your reasoning now. Whatever you choose, record why, so that in year seven of underperformance you are arguing with your own documented reasoning rather than with a headline.

This is education, not individualized financial advice. Your currency of future spending, your tax situation, and the fund menu in your retirement plan all reasonably affect where in this range you land.

Implementation: funds, costs, and taxes

Fund choice. A single total international stock index fund is the simplest complete solution: it covers developed and emerging markets, large and small companies, at expense ratios commonly in the 0.05% to 0.12% range. Splitting into separate developed and emerging funds gives you control over the emerging weight and occasionally slightly lower blended cost, at the price of another rebalancing decision. For most people the single fund wins on simplicity.

Costs to check. Expense ratio first. Then, for exchange-traded funds, the bid-ask spread, which is wider on thinly traded international funds than on the largest US ones. Avoid actively managed international funds charging 0.75% or more; the cost hurdle in a market with lower expected returns is punishing, and the evidence on persistent active outperformance is no better abroad than at home.

The foreign tax credit. Foreign governments typically withhold tax on dividends paid to US investors. If you hold international funds in a taxable account, you can generally claim a foreign tax credit that recovers much of that withholding. In a tax-advantaged account (IRA or 401(k)) you cannot claim the credit, so the withholding is simply lost. This is a modest but genuine argument for holding international stock funds in taxable accounts when you have the choice, and it is roughly the opposite of the placement logic for REITs and taxable bonds. The amounts are typically small, in the range of a few basis points to a couple of tenths of a percent per year, so treat it as a tiebreaker rather than a driver. Tax rules change; confirm details with a tax professional for your situation.

What not to bother with. Country-specific funds for individual small markets, currency-hedged international stock funds (for the reasons above), and single-stock foreign bets in markets whose accounting and governance you cannot evaluate. If the reason you want a specific country fund is a story you read, that is the market's story too, and it is in the price.

Common mistakes

• Setting the international allocation by looking at the last decade. This is the mistake that produces buying high and selling low with a ten-year lag.
• Believing multinational revenue substitutes for international ownership. Return behavior is driven by listing country and sector far more than by customer geography, and the 2010s divergence proves it empirically.
• Hedging currency on international stocks (paying to remove a diversifier) while leaving international bonds unhedged (accepting a risk that swamps the asset). Both backwards.
• Buying emerging markets for GDP growth. Cross-country evidence over a century shows essentially no positive link between economic growth and equity returns. Dilution and pricing absorb it.
• Treating emerging markets as diversified. A handful of countries and a few enormous technology companies typically dominate the index.
• Ignoring political and expropriation risk. Russia in 2022 is the reminder that in some markets you may not be able to sell at any price.
• Abandoning the allocation mid-cycle. Every diversifier looks like a mistake right up until it does not. Changing the plan in year eight of a nine-year drought is the classic failure.
• Paying up for active international management on the theory that foreign markets are less efficient. The persistence evidence does not support the premium.

Bottom line. Owning international stocks does not raise your expected return, and anyone who tells you it does is guessing. What it does is remove a single-country bet from your portfolio that you almost certainly did not intend to make. The world is roughly a third non-US by market value, the historical record shows leadership rotating in decade-long swings, and Japan is the standing proof that "our market is structurally superior" can be the most expensive sentence in investing. Pick something in the 20% to 40% range, write down why, and then leave it alone through the years when it looks wrong.