The Size of the World's Stock Markets and the U.S. Share
If you drew all the world's stocks as a single pie, how big would that pie be and who would hold the largest slice? And if one country held half of it, is that an opportunity or a risk?
How much is all the world's stock combined?
According to data from SIFMA, an international financial industry body, at the end of 2024 the market capitalization of all listed stocks worldwide (the sum of the value of every company's stock) was on the order of $126 trillion. It's such an enormous number that it's hard to grasp.
Market capitalization is 'share price x number of shares outstanding' — think of it as the market's valuation of a company (or an entire market). This pie rises and falls each year; in 2024 it grew by about 9% from a year earlier.
What matters is not the absolute amount but 'who holds how much.' The world's stock markets vary enormously in size from country to country.
The U.S. holds roughly half
The most striking fact is the U.S. share. In various tabulations, at the end of 2024 U.S. stocks accounted for about 50% or so of global market capitalization. One country held about half of the world's stocks.
Why is it so large? Many of the world's largest companies — Apple, Microsoft, Nvidia — are listed in the U.S., and as these large tech stocks rose sharply over the past few years, the U.S. share climbed even higher.
The remaining half is divided among dozens of countries — Japan, China, Europe, India, Korea, and others. In other words, you have to add up the entire 'rest of the world' excluding the U.S. just to come close to matching the U.S.
The 'about 50%' figure varies slightly, between 48% and 50%, depending on the tabulating body and the reference date. Rather than a single fixed value, it's more accurate to understand it as 'around half.'
Is 'U.S. concentration' an opportunity or a risk?
A large U.S. share is a double-edged sword.
The upside is that, because top-quality global companies are concentrated there, even a globally diversified product (for example, a whole-world stock index) will naturally hold a lot of large U.S. stocks.
On the other hand, there's a caveat. Today's high share is also a result of 'the U.S. having done especially well recently.' Historically, there have been cases where a particular country dominated the world market and then saw its share shrink. In the late 1980s, Japanese stocks once held a very large share of world market cap, but then underperformed for a long time.
So you shouldn't conclude that 'the share is large now, so it'll stay large.' This article is not telling you to buy a particular country's stocks; it's about understanding the map of the world's markets.
Frequently Asked Questions
Q. If the U.S. is half, does investing in the whole world's stocks amount to investing in the U.S. anyway?
To a large extent, yes. A product that tracks a world market-cap-weighted index holds by market-cap weight, so the U.S. accounts for about half. Even 'global diversification' means, in practice, a large weighting in large U.S. stocks — something you should be aware of.
Q. So is there no need to invest in countries other than the U.S.?
You can't conclude that. The rankings of country-by-country performance have shifted over time, and concentrating in a single market means the whole thing is shaken when that market underperforms. How much to hold and where is a matter for each person to judge based on their own investment horizon and profile, and this article does not offer a right answer.
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