In a setting with information asymmetry and a tradable value-weighted market index, ambiguity averse investors hold undiversified portfolios, and assets have non-zero alphas. But when a passive fund offers the risk-adjusted market portfolio (RAMP) whose weights depend on information precisions...

We analyze the effect of ambiguous loss probabilities on competitive insurance markets with asymmetric information. We characterize equilibria under actuarially fair pricing with preferences that are second-order ambiguity averse (have smooth indifference curves). We also show existence of...

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...