The aim of the paper is to discuss the important role of the dependence structure in risk management. Therefore, we focus on creditrisk and propose an innovative model to value the credit risk of a portfolio. This new approach (HYC for short) is based on a hierarchical hybrid copula and involves a clusterization of the portfolio in several risk’s classes. The HYC model is classified as hybrid because the computation of the loss cdf depends on the class’s cardinality: for large groups one is justified to apply a limiting approach, while for small ones one applies a procedure preserving the granularity of the group itself. In order to appreciate the impact of the dependence structure in credit-risk evaluation, a VaR analysis based on the HYC loss function is here compared to the CreditMetrics approach in an in-sample exercise and to the empirical VaR in an out-of sample exercise aimed to test the forecasting effectiveness of the model. This comparison allows us to appreciate over/under-valuation of the capital detained from the financial institution. Moreover, the impact of an enlargement of the dependence structure is discussed with respect to the systemic/contagious effects in the context of a portfolio optimisation with constraint on a sub-portfolio’s risk.

Silvia Romagnoli, Enrico Bernardi, Matteo Doti (2019). The impact of the dependence structure in risk management: a focus on credit-risk. INTERNATIONAL JOURNAL OF GENERAL SYSTEMS, 48(4), 335-361 [10.1080/03081079.2019.1579211].

The impact of the dependence structure in risk management: a focus on credit-risk

Silvia Romagnoli
;
Enrico Bernardi
;
Matteo Doti
2019

Abstract

The aim of the paper is to discuss the important role of the dependence structure in risk management. Therefore, we focus on creditrisk and propose an innovative model to value the credit risk of a portfolio. This new approach (HYC for short) is based on a hierarchical hybrid copula and involves a clusterization of the portfolio in several risk’s classes. The HYC model is classified as hybrid because the computation of the loss cdf depends on the class’s cardinality: for large groups one is justified to apply a limiting approach, while for small ones one applies a procedure preserving the granularity of the group itself. In order to appreciate the impact of the dependence structure in credit-risk evaluation, a VaR analysis based on the HYC loss function is here compared to the CreditMetrics approach in an in-sample exercise and to the empirical VaR in an out-of sample exercise aimed to test the forecasting effectiveness of the model. This comparison allows us to appreciate over/under-valuation of the capital detained from the financial institution. Moreover, the impact of an enlargement of the dependence structure is discussed with respect to the systemic/contagious effects in the context of a portfolio optimisation with constraint on a sub-portfolio’s risk.
2019
Silvia Romagnoli, Enrico Bernardi, Matteo Doti (2019). The impact of the dependence structure in risk management: a focus on credit-risk. INTERNATIONAL JOURNAL OF GENERAL SYSTEMS, 48(4), 335-361 [10.1080/03081079.2019.1579211].
Silvia Romagnoli; Enrico Bernardi; Matteo Doti
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/677090
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