Historical data based analysis suggesting that US S&P 500 will have near zero returns over the next 10 years & approx. 5% over the next 20 years.
This is also in line with previous such data published by JP Morgan
The Shiller CAPE ratio of the S&P 500 stands at 40.6 against an average of 22 from 1970.
Data sources: Robert Shiller S&P 500 data, real total returns, monthly starting points since Jan 1950; CAPE average data from MSCI USA P/E via Asset Camp