Comment

Abstract

Hubmer, Krusell, and Smith use a heterogeneous agent model to quantify the sources ofwealth inequality in the United States since 1960. They find that the substantial decline of US tax progressivity is a key driver of wealth inequality in the United States. Two other keymodel features are (1) allowing for heterogeneous returns and (2) portfolio heterogeneity. My comments focus on the threemain determinants thatHubmer et al. emphasize, which I agree are quite important, and then discuss a few other drivers ofwealth inequality that strikeme asfirst order andworthy of more analysis and discussion in future work.