We did so many versions that we decided to focus on the simple one. We published it here. It has 8 innovation series.
5 asset classes (all returns are total, nominal):
- US stocks
- developed stocks
- emerging stocks
- 10-year Treasury bonds
- corporate bonds
4 market factors:
- Measure (last day of year)
- Volatility (annual)
- BAA rate (average daily December)
- 10-year Treasury rate (average daily December)
Features: This is NOT a stationary model. All innovations are IID Gaussian, tested by Shapiro-Wilk and Jarque-Bera normality tests, and by the Ljung-Box test for 5 and 10 lags for original and absolute values of innovations.
Updates:
- Volatility and S&P returns data thanks to Angel Piotrowski and Ian Anderson, 1928-2025
- Rate data for BAA and 10-year Treasury extended back to 1925 from 1927
- Corporate bond returns data extended 1926-1973 using Ibbotson SBBI data thanks to Smaila Amoanu
- Yeo-Johnson transform of log volatility with index -0.5 modeled as autoregression with lag 1
- Log risk spread of logs as autoregression with lag 1
- Valuation measure modeled as autoregression with lag 1 with stochastic volatility
- Log BAA rate as random walk with stochastic volatility
- Treasury 10-year returns (coupon bonds) deterministic formula thanks to Aswath Damodaran
- Corporate bond returns minus rates (log duration) as a function of rate change
- Domestic, developed, emerging stocks vs rate change and valuation measure (not risk spread) with stochastic volatility
Future Research:
- A version with an objective Bayes inference for regression coefficients
- An online version instead of the old version with only 3 asset classes and non-Gaussian innovations
- Front end redesign, Smaila promised to do this
- New versions of the main model: For international stocks, its own dividend-based valuation measure rather than rely on US-based; for Treasury bonds, use actual returns data from SBBI or FRED to compare with predicted returns from Damodaran’s formula
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