Modelling the term-structure of default risk under IFRS 9 within a multistate regression framework

Fuente: arXiv
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Hauptverfasser: Botha, Arno, Verster, Tanja, Breedt, Roland
Format: Preprint
Veröffentlicht: 2025
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author Botha, Arno
Verster, Tanja
Breedt, Roland
author_facet Botha, Arno
Verster, Tanja
Breedt, Roland
contents The lifetime behaviour of loans is notoriously difficult to model, which can compromise a bank's financial reserves against future losses, if modelled poorly. Therefore, we present a data-driven comparative study amongst three techniques in modelling a series of default risk estimates over the lifetime of each loan, i.e., its term-structure. The behaviour of loans can be described using a nonstationary and time-dependent semi-Markov model, though we model its elements using a multistate regression-based approach. As such, the transition probabilities are explicitly modelled as a function of a rich set of input variables, including macroeconomic and loan-level inputs. Our modelling techniques are deliberately chosen in ascending order of complexity: 1) a Markov chain; 2) beta regression; and 3) multinomial logistic regression. Using residential mortgage data, our results show that each successive model outperforms the previous, likely as a result of greater sophistication. This finding required devising a novel suite of simple model diagnostics, which can itself be reused in assessing sampling representativeness and the performance of other modelling techniques. These contributions surely advance the current practice within banking when conducting multistate modelling. Consequently, we believe that the estimation of loss reserves will be more timeous and accurate under IFRS 9.
format Preprint
id arxiv_https___arxiv_org_abs_2502_14479
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Modelling the term-structure of default risk under IFRS 9 within a multistate regression framework
Botha, Arno
Verster, Tanja
Breedt, Roland
Risk Management
Statistical Finance
Applications
The lifetime behaviour of loans is notoriously difficult to model, which can compromise a bank's financial reserves against future losses, if modelled poorly. Therefore, we present a data-driven comparative study amongst three techniques in modelling a series of default risk estimates over the lifetime of each loan, i.e., its term-structure. The behaviour of loans can be described using a nonstationary and time-dependent semi-Markov model, though we model its elements using a multistate regression-based approach. As such, the transition probabilities are explicitly modelled as a function of a rich set of input variables, including macroeconomic and loan-level inputs. Our modelling techniques are deliberately chosen in ascending order of complexity: 1) a Markov chain; 2) beta regression; and 3) multinomial logistic regression. Using residential mortgage data, our results show that each successive model outperforms the previous, likely as a result of greater sophistication. This finding required devising a novel suite of simple model diagnostics, which can itself be reused in assessing sampling representativeness and the performance of other modelling techniques. These contributions surely advance the current practice within banking when conducting multistate modelling. Consequently, we believe that the estimation of loss reserves will be more timeous and accurate under IFRS 9.
title Modelling the term-structure of default risk under IFRS 9 within a multistate regression framework
topic Risk Management
Statistical Finance
Applications
url https://arxiv.org/abs/2502.14479