Heterogeneous credit portfolios and the dynamics of the aggregate losses

https://doi.org/10.1016/j.spa.2009.03.006Get rights and content
Under an Elsevier user license
open archive

Abstract

We study the impact of contagion in a network of firms facing credit risk. We describe an intensity based model where the homogeneity assumption is broken by introducing a random environment that makes it possible to take into account the idiosyncratic characteristics of the firms. We shall see that our model goes behind the identification of groups of firms that can be considered basically exchangeable. Despite this heterogeneity assumption our model has the advantage of being totally tractable. The aim is to quantify the losses that a bank may suffer in a large credit portfolio. Relying on a large deviation principle on the trajectory space of the process, we state a suitable law of large numbers and a central limit theorem useful for studying large portfolio losses. Simulation results are provided as well as applications to portfolio loss distribution analysis.

MSC

60K35
91B70

Keywords

Central limit theorems in Banach spaces
Credit contagion
Intensity based models
Large deviations
Large portfolio losses
Random environment

Cited by (0)