Shiller’s CAPE, first published in 2000, is sometimes used to try to predict long-term stock returns. How has CAPE done post-discovery? (CAPE is not a timing signal, and so is not actionable for most people.) For this post I will use perhaps the simplest prediction:
Subsequent 10-Year Annualized Real Return = 1 / CAPE
There are more complicated formulas used, but I will stay with this simple formula for this post. The Shiller data is monthly, but there are only 14 independent 10-year periods. Picking one at random for discussion (sorted by Error):
Date CAPE CAEY 10ySR Error Inflation_10yS
**2011.06 22.1 4.5% 12.8% -8% 2%**
1951.06 11.6 8.6% 15.1% -7% 1%
1991.06 18.0 5.6% 11.9% -6% 3%
1891.06 15.7 6.4% 10.8% -4% 0%
1901.06 25.2 4.0% 4.4% 0% 2%
1941.06 12.2 8.2% 8.3% 0% 6%
1981.06 8.8 11.4% 11.0% 0% 4%
1961.06 20.3 4.9% 4.4% 1% 3%
1881.06 19.0 5.3% 4.0% 1% -2%
**2001.06 33.1 3.0% -0.1% 3% 2%**
1921.06 5.2 19.2% 15.3% 4% -2%
1931.06 15.1 6.6% 2.5% 4% 0%
1971.06 17.1 5.9% -1.0% 7% 8%
1911.06 15.3 6.5% -4.6% 11% 7%
Where Error = CAEY - 10ySR, and Inflation_10yS is Subsequent 10-Year Annualized Inflation.
CAEY = 1/CAPE
The 2 post-discovery decades had Errors of 3% and -8%. One accurate prediction (2001) and one prediction that was too pessimistic (2011). These Errors are similar to those seen in 1940s and 1950s (0% and -7% Errors) and 1980s and 1990s (0% and -6% Errors).
There were 2 decades when CAPE was too optimistic, maybe because investors got more bad news than normal: the 1910s and 1970s. Stagflation, oil price shocks, World War I, and the Spanish flu pandemic made business difficult. Inflation was above 7% in these 2 decades, and that reduced real returns. Investors’ sinking optimism was reflected in sinking CAPE values (from 15 to 5, and 17 to 9 over these decades). Stock returns were low (-5% and -1% real 10-year annualized).
There were 3 decades when CAPE was too pessimistic: the 1950s, 1990s, and 2010s. Inflation was low, and there were some surprises (dot-com bubble, COVID-19 pandemic), but investors’ rising optimism was reflected in rising CAPE values (from 12 to 20, 18 to 33, and 22 to 37 over these decades). Stock returns were high (15%, 12%, and 13% real 10-year annualized).
Using BCC=0 timing improves results mostly in the decades when CAPE was too optimistic: 1930s, 1970s, and 2000s.
10ySR Error improvement
Date CAEY 10ySR wBCC0 Error wBCC0 wBCC0
2011.06 4.5% 12.8% 10.3% -8% -6% -2%
1951.06 8.6% 15.1% 14.4% -7% -6% 0%
1991.06 5.6% 11.9% 12.1% -6% -7% 0%
1941.06 8.2% 8.3% 7.3% 0% 1% -1%
1981.06 11.4% 11.0% 12.4% 0% -1% 1%
1961.06 4.9% 4.4% 5.3% 1% 0% 1%
2001.06 3.0% -0.1% 5.8% 3% -3% 6%
1931.06 6.6% 2.5% 10.2% 4% -4% 7%
1971.06 5.9% -1.0% 1.3% 7% 5% 3%
---- links ----
“The current S&P500 10-year P/E Ratio is 29.9. This is 49% above the modern-era market average of 19.6, putting the current P/E 1.2 standard deviations above the modern-era average. This suggests that the market is Overvalued.”
https://www.currentmarketvaluation.com/models/price-earnings…
“According to data first presented in “Irrational Exuberance” (which was released in March 2000, coinciding with the peak of the dotcom boom), and updated to cover the period 1881 to August 2020, the ratio has varied from a low of 4.78 in December 1920 to a high of 44.20 in December 1999.”
https://www.investopedia.com/terms/p/pe10ratio.asp
https://en.wikipedia.org/wiki/Cyclically_adjusted_price-to-e…
“Expected returns (nominal, annualized over the next 10 years) = Starting Dividend Yield + Earnings Growth rate + Percentage change (annualized) in the P/E multiple.”
https://alphaarchitect.com/2021/03/predicting-stock-returns-…
Markets: Exuberance is not always ‘irrational’, July 25, 2014
“Any comparison of valuations covering long periods is meaningless if it fails to take into account vast changes in technology, economic policies, interest rates, social and political structures, and taxes… Recent evidence is conclusive: For the past 25 years, the Shiller ratio’s signals have been almost uniformly wrong.”
http://web.archive.org/web/20150507071031/http://blogs.reute…
“for me the anomaly does not seem to be a CAPE of 25 (or, given historical real returns on other asset classes and very low current yields on investments naked to inflation risk, 33) but rather the CAPEs of 14-20 that we saw in the 1980s, 1960s, 1950s, 1900s, 1890s, and 1880s that Robert Shiller appears to think of as “normal” and to which today’s CAPE should someday return.”
https://delong.typepad.com/sdj/2014/08/under-what-circumstan…