Modeling Credit Risk with Partial Information

Abstract

This paper provides an alternative approach to Duffie and Lando (2001) for obtaining a reduced form credit risk model from a structural model. Duffie and Lando obtain a reduced form model by constructing an economy where the market sees the manager's information set plus noise. The noise makes default a surprise to the market. In contrast, we obtain a reduced form model by constructing an economy where the market sees a reduction of the manager's information set. The reduced information makes default a surprise to the market. We provide an explicit formula for the default intensity based on an Azema martingale, and we use excursion theory of Brownian motions to price risky debt.

Keywords: Default risk, Azema martinglae, Brownian excursion

JEL Classification: G12, G33