Optimal Portfolio Choice under Decision-Based Model Combinations

Abstract

We propose a density combination approach featuring combination weights that depend on the past forecast performance of the individual models entering the combination through a utility-based objective function. We apply this model combination scheme to forecast stock returns, both at the aggregate level and by industry, and investigate its forecasting performance relative to a host of existing combination methods, both within the class of linear and time-varying coefficients, stochastic volatility models. Overall, we find that our combination scheme produces markedly more accurate predictions than the existing alternatives, both in terms of statistical and economic measures of out-of-sample predictability.

Keywords: Bayesian econometrics, Time-varying parameters, Model combinations, Portfolio choice

JEL Classification: C11, C22, G11, G12