Under diversification, as you are describing, is the first ingredient… I suspect the second ingredient is US boomers right on the edge of retirement or otherwi

Under diversification, as you are describing, is the first ingredient… I suspect the second ingredient is US boomers right on the edge of retirement or otherwise shifting to fixed income… And a normal correction causes all of them to divest simultaneously from equities. There is a potential for a stampede out of US equities.