everyone got all-in equities... and not just retail investors and US households, but mutual funds, hedge funds, pensions, systematic, and sovereign wealth funds.
As JPMorgan calculated when looking at the equity positioning of the main types of investors, "allocations are near historical highs, not leaving much room for further increases." How historic?
Starting with retail investors one can notice that margin debt (measured as percentage of market capitalization) is at its highest point ever, which includes the 2000 tech bubble episode. The percentage of US household wealth in equities is in its 94th percentile and above its 2007 peak, but slightly below 2000 levels. Sovereign wealth funds and US mutual funds are also near record levels. Pension Fund allocations appear to be in the 88% percentile, although there is some uncertainty around this number in adjusting for private asset and HF holdings.