DEFAULTABLE TERM STRUCTURES DRIVEN BY SEMIMARTINGALES

In this paper, we consider a market with a term structure of credit risky bonds in the single-name case. We aim at minimal assumptions extending existing results in this direction: first, the random field of forward rates is driven by a general semimartingale. Second, the Heath–Jarrow–Morton (HJM) approach is extended with an additional component capturing those future jumps in the term structure which are visible from the current time. Third, the associated recovery scheme is as general as possible, it is only assumed to be nonincreasing. In this general setting, we derive generalized drift conditions which characterize when a given measure is a local martingale measure, thus yielding no asymptotic free lunch with vanishing risk (NAFLVR), the right notion for this large financial market to be free of arbitrage.

Non-Homogeneous Semi-Markov and Markov Renewal Processes and Change of Measure in Credit Risk

For a G-inhomogeneous semi-Markov chain and G-inhomogeneous Markov renewal processes, we study the change from real probability measure into a forward probability measure. We find the values of risky bonds using the forward probabilities that the bond will not default up to maturity time for both processes. It is established in the form of a theorem that the forward probability measure does not alter the semi Markov structure. In addition, foundation of a G-inhohomogeneous Markov renewal process is done and a theorem is provided where it is proved that the Markov renewal process is maintained under the forward probability measure. We show that for an inhomogeneous semi-Markov there are martingales that characterize it. We show that the same is true for a Markov renewal processes. We discuss in depth the calibration of the G-inhomogeneous semi-Markov chain model and propose an algorithm for it. We conclude with an application for risky bonds.

NEW MODEL FOR PRICING QUANTO CREDIT DEFAULT SWAPS

We propose a new model for pricing quanto credit default swaps (CDS) and risky bonds. The model operates with four stochastic factors, namely: the hazard rate, the foreign exchange rate, the domestic interest rate, and the foreign interest rate, and allows for jumps-at-default in both the foreign exchange rate and the foreign interest rate. Corresponding systems of partial differential equations are derived similar to how this is done by Bielecki et al. [PDE approach to valuation and hedging of credit derivatives, Quantitative Finance 5 (3), 257–270]. A localized version of the Radial Basis Function partition of unity method is used to solve these four-dimensional equations. The results of our numerical experiments qualitatively explain the discrepancies observed in the marked values of CDS spreads traded in domestic and foreign economies.

Sovereign Default Risk and Banks in a Monetary Union

This study seeks to understand the interplay between banks, bank regulation, sovereign default risk and central bank guarantees in a monetary union. I assume that banks can use sovereign bonds for repurchase agreements with a common central bank, and that their sovereign partially backs up any losses should the banks not be able to repurchase the bonds. I argue that regulators in risky countries have an incentive to allow their banks to hold home risky bonds and risk defaults, whereas regulators in other ‘safe’ countries will impose tighter regulation. As a result, governments in risky countries get to borrow more cheaply, effectively shifting the risk of some of the potential sovereign default losses on the common central bank.