From this paper:
Emerging markets have > 30% world GDP, but only 12% of world market cap. A Shiller CAPE of about 15. 55% of global population.
The US is about 25% of world GDP, but 45% of world market cap. And a Shiller CAPE of about 24. 5% of global population.
Now, how much of your portfolio of stocks is in the US? My guess for most is 50, 75, or 100%.
(also here is a related piece from Vanguard)
Given the dramatic globalization over the past twenty years, does it make sense to segregate global equities into “developed” and “emerging” market buckets? We argue that the answer is still yes. While correlations between developed and emerging markets have increased, the process of integration of these markets into world markets is incomplete. To some degree, this accounts for the disparity between emerging equity market capitalization in investable world equity market benchmarks versus emerging market economies in the world economy. Currently, emerging markets account for more than 30% of world GDP. However, they only account for 12.6% of world equity capitalization. Interestingly, this incomplete integration along with the relatively small equity market capitalization creates potentially attractive investment opportunities. Our research has important policy implications for institutional fund management.