To date, researchers in this area have generally used only broad equity indexes in their work. (aaii.com)
High yielders have tended to outperform broad equity indexes in times of economic contraction, based on our analysis of PMI data. (blackrockblog.com)
Hi Professor Damodaran, In discussing mean reversion for broad equity indexes, here are a few factors that seem potentially relevant, which I didn't find mention of in your post: 1) Technology network effect: technology revolutions (electricity, transistor, computer, internet, etc) engender decades - long streaks of further invention and commercialization. (aswathdamodaran.blogspot.ru)