We study optimal securitization of defaultable assets in a continuous time setting. A financial intermediary can create a portfolio of defaultable assets and then sell it to outside investors. The default risk of the assets in the portfolio is determined by the unobservable costly effort exerted...

We solve the problem of optimal securitization for an issuer facing heterogeneous investors with arbitrary time and risk preferences. We show that the optimal securitization is characterized by multiple nonlinear tranches, and each investor gets a portfolio of these tranches. In particular, when...

We solve the general problem of optimal risk sharing among a nite number of agents with limited liability. We show that the optimal allocation is characterized by endogenously determined ranks assigned to the participating agents and a hierarchical structure of risk sharing, where all agents...