
 The Grouped tcopula with an Application to Credit Risk by Stéphane Daul of Swiss Re, November 2003 Abstract: We describe a model that takes into account the tail dependence present in a large set of historical risk factor data using the modern concept of copulas. We extend the popular tcopula to obtain a new grouped tcopula which describes more accurately the dependence among risk factors of different classes. We explain how to estimate the parameters of the grouped tcopula and apply the method to a problem in credit risk management with a large number of risk factors. We measure the downside risk over one month for an internationally diversified credit portfolio and we observe that the new model gives different results to the tcopula and seems better able to capture the risk in a large set of risk factors. Published in: RISK, Vol. 16, No. 11, (November 2003), pp. 7376. Books Referenced in this paper: (what is this?) 