Published online by Cambridge University Press: 08 February 2024
Machine learning-based stock market beta estimators outperform established benchmark models both statistically and economically. Analyzing the predictability of time-varying market betas of U.S. stocks, we document that machine learning-based estimators produce the lowest forecast and hedging errors. They also help to create better market-neutral anomaly strategies and minimum variance portfolios. Among the various techniques, random forests perform the best overall. Model complexity is highly time-varying. Historical stock market betas, turnover, and size are the most important predictors. Compared to linear regressions, allowing for nonlinearity and interactions significantly improves predictive performance.
We thank two anonymous referees, Yakov Amihud, Michael Bauer, Wolfgang Bessler, Axel Cabrol, Mikhail Chernov, Hubert Dichtl, Thierry Foucault (the editor), Kay Giesecke, Lisa Goldberg, Valentin Haddad, Barney Hartman-Glaser, Bernard Herskovic, Bryan Kelly, Serhiy Kozak, Markus Leippold, Martin Lettau, Lars A. Lochstoer, Harald Lohre, Tyler Muir, Andreas Neuhierl, Terrance Odean, Stavros Panageas, Markus Pelger, Tatjana Puhan, Carsten Rother, Boris Vallee, Michael Weber, and Ivo Welch for helpful comments and suggestions.