US investors are running domestic concentration that would be almost unrecognizable to investors from any other decade. The average US equity portfolio is 87 percent domestic, against a global market cap weight that is closer to 60 percent domestic. The Morningstar 2026 home-bias study put the gap at the highest reading on record. Most of that concentration came from the past decade of US outperformance compounding inside index funds, not from active decisions to ignore international stocks. The result is a portfolio whose performance has been spectacular and whose valuation premium against the rest of the world has never been wider.
The valuation gap in 2026 is the longest stretch in modern market history. The S&P 500 trades at roughly 22.8 times forward earnings. MSCI EAFE, which covers developed international markets, trades at 14.4. MSCI Emerging Markets trades at 11.7. The premium of US stocks over EAFE is at 8.4 turns of earnings, the widest since 1999. The premium over emerging markets is wider still. Valuation premiums of this size have historically reverted, though the timing of the reversion has been notoriously hard to predict.
The earnings growth gap that justified some of the premium is narrowing in 2026. US earnings growth in Q1 came in at 9.4 percent year over year. EAFE earnings growth came in at 7.8 percent. Emerging markets earnings growth came in at 11.4 percent. The narrative that US companies are uniquely positioned to grow faster than international peers held in 2023 and 2024. It is harder to defend in 2026, particularly with emerging markets earnings outpacing the US.
The dollar story is the third leg, and it cuts in favor of international equities for the first time in years. The DXY index sits at 96.4, down from a peak of 108 in late 2023. A weakening dollar amplifies international equity returns in dollar terms. An EAFE stock that returns 10 percent in local currency returns approximately 12 to 14 percent to a US investor when the dollar weakens 2 to 4 percent against the relevant basket. The relationship is mechanical, and it has worked against international diversification for the entire post-2014 period. It is starting to work in favor of it.
The sectors driving international upside in 2026 are different from the US drivers. US returns concentrated in technology and communication services. International returns are coming from financials, industrials, and consumer discretionary. EAFE banks are returning 18 percent year to date against a backdrop of normalized interest rate margins and rising loan growth. Japanese industrials are running double-digit operating margin expansion. European luxury goods companies are showing renewed strength after a difficult 2024. The composition of the international index is structurally less tech-heavy than the US, which has been a drag for a decade and is becoming a feature in 2026.
Implementation matters as much as the allocation decision. The cheapest broad international exposure is VXUS at 0.07 percent expense ratio, covering both developed and emerging markets. IEFA covers developed markets only at 0.07 percent. AVDV is a small-cap developed value fund running at 0.36 percent. AVES is the equivalent emerging markets fund at 0.36 percent. For most investors, a single VXUS position covering total international gets the job done. Adding a tilt toward small-cap value internationally has historically improved long-run risk-adjusted returns, though the trade-off is higher fees and tracking error.
The allocation question for a US investor moving from 87 percent domestic toward something closer to neutral comes down to risk tolerance and behavior. A mechanical move to 60 percent domestic and 40 percent international hits the global market cap weight and is academically defensible. A more conservative move to 70 percent domestic and 30 percent international captures most of the diversification benefit with less near-term tracking error against the US-only crowd. A 80-20 split is the smallest meaningful tilt away from full home bias. Below 20 percent international, the diversification effect is negligible.
The behavioral cost of international exposure is the part most investors underestimate. International equities lag US equities for years at a time. The investor who reallocates after a decade of US outperformance is often the same investor who capitulates after the first two years of relative underperformance. The data on investor behavior consistently shows that the gap between fund returns and investor returns is widest in funds that have recent underperformance against the popular benchmark. The discipline to hold international through a multi-year stretch of US dominance is the actual constraint, not the academic case for diversification.
The 2026 setup looks more like 1999 than any year since. The valuation gap, the earnings growth narrowing, the weakening dollar, the sector composition shift. None of those guarantee a turn. They make the trade asymmetric. International stocks have been the worst trade in the developed world for ten years. Sometimes that is the cleanest setup the market offers.