In the finance literature, a common practice is to create factor-portfolios by sorting on characteristics (such as book-to-market, profitability or investment) associated with average returns. The goal of this exercise is to create a parsimonious set of factor-portfolios that explain the...

Ambiguity aversion alone does not explain the market nonparticipation puzzle. We show that in a rational expectations equilibrium model with a fund offering the risk-adjusted market portfolio (RAMP), ambiguity averse investors hold the fund and an information-based portfolio, and thus...