This paper analyzes optimal prevention in a situation of multiple, possibly correlated risks. We focus on probability reduction (self-protection) so that correlation becomes endogenous. If prevention concerns only one risk, introducing a second exogenous risk increases the level of prevention...

We study sources and implications of undiversified portfolios in a production-based asset pricing model with financial frictions. Households take concentrated positions in a single firm exposed to idiosyncratic shocks because managerial effort requires equity stakes, and because investors gain...