Respectfully, the lower Sharpe ratio from the perspective of a US investor diversifying from all US (no currency risk) to international stocks is not the relevant number to be considering here. We'd need the yen-based Sharpe ratio difference between switching from US to global stocks. Both sides of that coin have (different) currency risks, and that would change the returns and the volatility entering in to the Sharpe ratio calculation (i.e. it won't be the same as the number on that graph).TokyoWart wrote: ↑Thu Aug 17, 2023 11:05 am However, if you look at the graph the comes up on the video very briefly at 5:05 you see that from 1974-2021 (longer than my investing lifetime) US domestic investors actually lowered their Sharpe ratio if they diversified internationally. That result is counter to what CAPM would predict and the length of time for which diversification worked against the US domestic investor is long enough that it shouldn't be dismissed too quickly.
I suspect that this reflects in part how gloriously wealthy you are with investments compared to your current incomeTokyoWart wrote: ↑Thu Aug 17, 2023 11:05 am I agree with Ben that US stocks are richly priced now compared to other markets and for years now I have been trying to diversify my US portfolios so they have 20% international and "only" 80% US stocks but the relative outperformance of US stocks has meant that even when I put nearly all new cash and dividends into international indexes I can't get the allocation up to 20% international.
If you are coming from a base of 100% US stocks, in the recent climate of low US dividend yields, it could take a decade or two for this rebalancing strategy to reach 80/20, even if the US was not outperforming the RoW.