Aggregate portfolio choice

Abstract

Important portfolio choice decisions are made for large groups of heterogeneous individual investors. I propose solving the cross-sectional average of the individual Euler equations to find an optimal portfolio for an aggregate of investors under one-size-fits-all constraints. Using a dynamic portfolio choice model to design balanced default funds for 72 hypothetical industry pension plans, the average Euler equations depend on industry-specific per-capita earnings growth and moments of idiosyncratic earnings shocks. Inter-industry heterogeneity in moments of the joint distribution of earnings growth and the return on risky assets, including correlation and cokurtosis, explains the variation in optimal choice variables across industries.