What happens to the Shiller CAPE ratio when we roll out the weak 2008/09 earnings?
https://earlyretirementnow.com/2017/03/22/cape-fear/
I used to be a big believer in 'valuations', CAPEs and other things like that. You see the historical numbers and somehow feel this sense of control about how the market behaves. Then I decided to do my backtesting project of testing out allocations, portfolios, random tests using US data from the 1920s to 2000s. I learned quite a bit but a big lesson was, how quickly historical conclusions that you develop (or theories) are completely destroyed as you add more data. I learned how fragile 'empirical' stuff really is.
CAPE is a great example of that, it has a great history, then the 90's and 2000s come along and the true believers (people like John Hussman) blow up like there is no tomorrow because anyone that goes to cash, buy puts like crazy, shorts based on that, is inherently short the convexity of the stock market. And when you do that, you need to be right a huge % of the time. Stock market 'idiots' on the other hand (the ones buying at 'crazy' valuations) don't need to be right as often. Worse case, they overpaid some but that is fine because people get salaries, dividends, interest income and a fall will enable them to invest those proceeds at better prices/implied returns. Therefore what the true idiots are afraid of (folks like Hussman and Jeremy Grantham) is actually a bening risk people shouldn't even care much about. Its a lot worse watching markets go up for years/a decade without you, then to overpay some for an investment
But if someone needs follow this CAPE religion that badly, here is a way to do it:
Sell out of that market that has the high CAPE that one is afraid about but immediatly rebuy another that has a much lower CAPE (a different country stock market, or better, several countries). That way, if selling was a mistake in the first place, the repurchase of a different market is likely to offset that mistake
Worst thing you do is to join the church of CAPE and then go to cash, post bearish articles around, short, buy puts like they are going out of style, etc.
I learned this lesson the painful way, by watching something rise exponentially for years without me on board. I wish I had more critical thinking of this 'empirical' crap back in the day
This valuation stuff only truly works with figuring out what is 'cheap', there is a zero bound to the downside that makes estimates a lot easier. Finding out when something is too expensive is a lot more difficult because stocks are unbounded to the upside (so are nominal and real earnings)