The Relationship between Counterparty Default and Interest Rate Volatility and its Impact on the Credit Risk of Interest Rate Derivatives

We present a unified framework to study the effect of the correlation between interest rate volatility and counterparty default probability on the credit risk of collateralized interest rate derivatives contracts. When interest rates are volatile, counterparties are potentially more likely to default. Large moves in interest rates accompanied by counterparty default may lead to losses on interest rate derivatives, even if they are collateralized. An interest rate model with stochastic volatility and a reduced form default model, in which the default probability is correlated with interest rate volatility, are proposed and estimated from market data. We then analyze the effect of the correlation between interest rate volatility and a counterparty's default probability on the credit risk of collateralized interest rate derivatives contracts. Our results show that ignoring this correlation underestimates the credit risk, even with collateralized trades.