FYI: Ever since the Great Financial Crisis of 2007-2008, when the correlation of all risky assets rose toward 1, investors have been hearing that because of globalization, the world has become flat and the benefits of diversification are gone.
The explanation is generally that the world market has become more integrated and financial markets more globalized. This has led some investors to draw the wrong conclusions about the benefits of international diversification.
Regards,
Ted
https://www.etf.com/sections/index-investor-corner/swedroe-benefits-intl-diversification?nopaging=1
