Open Access
February 2014 Killed Brownian motion with a prescribed lifetime distribution and models of default
Boris Ettinger, Steven N. Evans, Alexandru Hening
Ann. Appl. Probab. 24(1): 1-33 (February 2014). DOI: 10.1214/12-AAP902

Abstract

The inverse first passage time problem asks whether, for a Brownian motion $B$ and a nonnegative random variable $\zeta$, there exists a time-varying barrier $b$ such that $\mathbb{P}\{B_{s}>b(s),0\leq s\leq t\}=\mathbb{P}\{\zeta>t\}$. We study a “smoothed” version of this problem and ask whether there is a “barrier” $b$ such that $\mathbb{E}[\exp(-\lambda\int_{0}^{t}\psi(B_{s}-b(s))\,ds)]=\mathbb{P}\{\zeta>t\}$, where $\lambda$ is a killing rate parameter, and $\psi:\mathbb{R}\to[0,1]$ is a nonincreasing function. We prove that if $\psi$ is suitably smooth, the function $t\mapsto\mathbb{P}\{\zeta>t\}$ is twice continuously differentiable, and the condition $0<-\frac{d\log\mathbb{P}\{\zeta>t\}}{dt}<\lambda$ holds for the hazard rate of $\zeta$, then there exists a unique continuously differentiable function $b$ solving the smoothed problem. We show how this result leads to flexible models of default for which it is possible to compute expected values of contingent claims.

Citation

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Boris Ettinger. Steven N. Evans. Alexandru Hening. "Killed Brownian motion with a prescribed lifetime distribution and models of default." Ann. Appl. Probab. 24 (1) 1 - 33, February 2014. https://doi.org/10.1214/12-AAP902

Information

Published: February 2014
First available in Project Euclid: 9 January 2014

zbMATH: 1328.60188
MathSciNet: MR3161639
Digital Object Identifier: 10.1214/12-AAP902

Subjects:
Primary: 60J70 , 91G40 , 91G80

Keywords: Cox process , credit risk , Feynman–Kac formula , inverse first passage time problem , killed Brownian motion , Stochastic intensity

Rights: Copyright © 2014 Institute of Mathematical Statistics

Vol.24 • No. 1 • February 2014
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