The United States is about half the world’s stock market. Most American portfolios behave as if it were all of it. Here’s why we build differently — with the history and the numbers.
American companies represent roughly 48% of world stock market value as of 2026 — a remarkable share, and a testament to American business. But it means the other half of the world’s opportunity set lives abroad. Meanwhile, the typical U.S. investor holds 90% or more of their stock portfolio in U.S. companies — a pattern economists call home country bias, and it exists in every country: Japanese investors overweight Japan, Germans overweight Germany. It isn’t analysis. It’s familiarity.
The strongest argument for global diversification isn’t a forecast. It’s a pattern that has repeated for a century: leadership rotates, and each era’s winner tends to become expensive precisely because it won — setting up the reversal.
Investors who assumed the 1980s belonged permanently to Japan learned the hardest version of this lesson. At its 1989 peak, Japan was the largest stock market on Earth — nearly half of world market value, celebrated as unstoppable. Its market then fell and took roughly 34 years to reclaim that high.
Americans have lived this lesson too, more gently: from 2000 through 2009 — the “lost decade” — the S&P 500 produced a negative total return over ten full years, while emerging markets and diversified global portfolios made money. Anyone retiring on a U.S.-only portfolio in that stretch felt the difference deeply.
Line up the world’s largest companies at the start of each decade and the same story repeats. Oil ruled 1980. Japan owned 1990 — at its peak, Japanese names filled most of the global top ten. The class of 2000 was internet and telecom; 2010 belonged to energy and China’s rise; today’s list is dominated by American technology. Each group looked unbeatable. Then the decade turned.
Zoom out from companies to countries and the rotation continues. U.S. and international stocks have swapped leadership in long, multi-year eras for as long as modern records run — and the handoffs often track the dollar, since a weakening dollar boosts what foreign returns are worth to a U.S. investor. The 2010s belonged decisively to American markets. The 1970s, the late 1980s, and the mid-2000s did not.
None of this tells us who leads the next decade — and that is precisely the point. Rotation is the norm, the turns are only obvious in hindsight, and the cost of guessing wrong compounds for years. Owning the whole field means never needing the guess.
After fifteen years of American dominance, the gap has grown historically wide: U.S. stocks trade at substantial valuation premiums to international markets, U.S. concentration in world indexes sits near records — and the tide has begun testing the consensus. In 2025, international stocks beat the S&P 500 by roughly 15 percentage points; through mid-2026 they lead again, and global fund flows into international markets have run roughly four times U.S. inflows. None of this proves the next decade belongs abroad. It simply illustrates the point: the turn always starts before the crowd believes it.
We build portfolios with a strong U.S. foundation — American markets remain the deepest and most innovative in the world — complemented by deliberate, meaningful exposure to international developed and emerging markets, sized to each client’s goals and risk limits rather than to a formula. We rebalance on discipline, not headlines, letting the process quietly buy low and trim high. And because global investing introduces currency movements, differing regulations, and periods of uncomfortable divergence from U.S. benchmarks, we treat those as manageable characteristics to plan around — not reasons to retreat to the familiar.