US, Europe and Asia: why not to invest in just one market
What each major region brings, why the winning market changes over time and how to combine them in a portfolio.
Oct 22, 2026 · 4 min read
In recent years, many people who start investing do so almost exclusively in the United States. It makes sense: it's the largest market, home to the best-known companies and easy to access from investing apps. But betting everything on a single market, however big, carries risks worth understanding.
The winning market changes
If you look at market history, you'll see that no region wins every time. There have been decades when the United States clearly led, and others when Europe, Japan or emerging markets did better. A widely cited example is Japan: after its boom in the late 1980s, its stock market took more than three decades to get back to those highs.
The lesson isn't that one market is better than another, but that it's very hard to know in advance which one will win the next decade. Diversifying across regions means accepting that uncertainty instead of betting against it.
What each region brings
United States
- Strengths: the largest and deepest market, a leader in technology, health care and financial services. Many of its companies sell all over the world.
- Risks: the index is increasingly concentrated in a small group of tech giants. If that group struggles, it drags the whole market down. Valuations also tend to be higher than in other regions.
You can explore its companies in United States.
Europe
- Strengths: industrial, pharmaceutical, luxury and energy giants. Many companies pay solid dividends. Currencies other than the dollar: the euro, the pound, the Swiss franc.
- Risks: slower economic growth, more traditional sectors and less weight in technology.
See the region in Europe or the European blue chips shortcut.
Asia-Pacific
- Strengths: Japan brings top-tier industry and technology; South Korea and Taiwan are the world's semiconductor heartland; India is one of the fastest-growing economies; China is the world's second-largest economy.
- Risks: very different realities from country to country, geopolitical and regulatory risks, and trading hours opposite to those of the Americas.
Explore Asia-Pacific.
Why combining them lowers risk
Regions don't move alike because they respond to different things: their own central banks, their currencies, their economic cycles and their dominant sectors. When one is suffering, another may be steady.
You can see this in correlation. Two indices with high correlation move almost identically; combining them adds little diversification. Two with low correlation offset each other better. When you calculate a portfolio in the optimizer, the heatmap shows you these relationships in color.
A technical detail: trading hours
The Tokyo exchange closes before New York opens. If important news breaks during the US session, Japan will react the next day. If you compare returns day by day, it will look like they move together less than they really do.
That's why, when you mix assets from Asia and the Americas, the optimizer uses weekly returns by default, which reduce that mismatch. You can change this in the advanced options.
How much in each region?
There's no single answer. Some reference points:
- Market weights: a world index like the MSCI ACWI puts the largest share in the United States and spreads the rest across Europe, Japan, emerging markets and others. Copying that proportion is a neutral option.
- Equal weights by region: more geographically diversified, although it moves away from the real size of each market.
- Optimization with limits: use the optimizer with constraints such as "at most 50% in North America" or "at least 15% in Asia-Pacific".
What matters is that the decision is deliberate, not an accident of which companies you happened to know.
An exercise
- Open the optimizer and load only ETFs: one for the United States, one for Europe, one for Japan and one for emerging markets.
- Calculate with equal weights and with minimum variance.
- Compare the volatility of each with that of a portfolio holding only the US ETF.
In most periods you'll see that the mix has lower risk than the average of its parts: that's diversification at work. The "Why these weights?" section explains it in words.
Frequently asked questions
Aren't US companies already diversified, since they sell all over the world? Partly, yes, but their share prices still depend heavily on the economy, the currency and the stock market of their home country.
Is investing in Asia riskier? It depends on the country. Japan is a developed, stable market; some Asian emerging markets are more volatile. What matters is how they fit with the rest of your portfolio.
Don't forget currencies
Each region comes with its own currency. A portfolio with the United States, Europe and Japan depends on the dollar, the euro and the yen, as well as your own currency. That mix also diversifies: at different times, some currencies strengthen while others weaken. In the optimizer you can see how much your portfolio depends on each currency in the exposure section, and choose your base currency so the calculation reflects your reality.
In short
The United States, Europe and Asia bring different things, and no region wins every time. Combining them reduces your dependence on a single market, a single currency and a single group of companies. Try your global combination and see the effect on risk.
Try it with your own assets
Build a list and see which portfolio the model calculates, in your currency.
Disclaimer: Educational and simulation tool. It is not investment advice or a personalized recommendation. Past performance does not guarantee future results.