In this paper, we use stochastic dynamic programming to study the intertemporal consumption and portfolio choice of an infinitely lived agent who faces a constant opportunity set and a borrowing constraint. We show that, under general assumptions on the agent's utility function, optimal policies exist and can be expressed as feedback functions of current wealth. We describe these policies in de...

This article studies an optimal stopping problem with an endogenous constraint on the set of admissible stopping times. The constraint stipulates that continuation is permitted, at any given date t, only if the endogenous reward achieved exceeds a prespecified threshold. Characterizations of the value function and the optimal stopping time are presented. An application to the pricing of corpora...

We consider mathematical models for portfolio credit risk. We analyze the mathematical structure and in particular the modelling of dependence between default events in these models and propose extensions of standard industry models. We study the model risk related to the choice of model structure and input parameters. Finally we develop and test several approaches to model calibration in credi...

This paper describes a pure-exchange, continuous-time economy with two heterogeneous agents and complete markets. A novel feature of the economy is that agents perceive some security returns as ambiguous in the sense often attributed to Frank Knight. The equilibrium is described completely in closed-form. After identifying agents as countries, the model is applied to address the consumption hom...

We introduce the multivariate Ornstein-Uhlenbeck process, solve it analytically, and discuss how it generalizes a vast class of continuous-time and discretetime multivariate processes. Relying on the simple geometrical interpretation of the dynamics of the Ornstein-Uhlenbeck process we introduce cointegration and its relationship to statistical arbitrage. We illustrate an application to swap co...

A fund’s performance is usually compared to the performance of an index or other funds. If a fund trails the benchmark, the fund manager is often replaced. We argue that this may lead to excessive risk-taking if fund managers differ in ability and have the opportunity to take excessive risk. To match the benchmark, fund managers may increase the risk of their portfolio even if this decreases th...

This paper derives and analyzes dynamic timing strategies of a fund manager with private information. Endogenous timing strategies generated by various information structures and skills, and associated fund styles, are identified. Endogenous fund returns are characterized in the public information of an uninformed observer. Timing components are identified. The paper provides foundations for re...

Owner-managers of private companies are often highly underdiversified. We investigate the consequences of underdiversification at the company level. There is a strong positive relationship between underdiversification, measured as the share of personal net worth invested in the company, and profitability, measured as the return on equity. The analysis identifies two causes for this underdiversi...