An equity-credit hybrid model for asset correlations
by Fabio S. Dias
International Journal of Financial Engineering and Risk Management (IJFERM), Vol. 3, No. 3, 2020

Abstract: Single factor Gaussian copula models are widely used to manage credit risk of loan portfolios, even driving how many large financial institutions are capitalised under Basel II/III. Under this formulation, the default correlation between two separate firms is directly explained by their asset correlation to a systematic factor, which can be estimated using either equity correlations or observed default rates, with the portfolio losses usually being simulated under a Gaussian copula model. Though it is widely accepted that the use of observed default rates or even equity returns to calibrate a single factor Gaussian copula model is likely to understate the tail risk. This paper proposes a Bayesian approach for a single factor Gaussian copula where the asset correlations are modelled using an inverse Wishart prior with the scale parameter calibrated to observed default rates and the degrees of freedom chosen using the in-sample continuous ranked probability score whilst the equity correlations are used to obtain the posterior distribution. The proposed hybrid model is shown to produce probabilistic forecasts of defaults with better out-of-sample performance than the standard single factor Gaussian copula even though it maintained low complexity and ease of implementation.

Online publication date: Mon, 08-Jun-2020

The full text of this article is only available to individual subscribers or to users at subscribing institutions.

 
Existing subscribers:
Go to Inderscience Online Journals to access the Full Text of this article.

Pay per view:
If you are not a subscriber and you just want to read the full contents of this article, buy online access here.

Complimentary Subscribers, Editors or Members of the Editorial Board of the International Journal of Financial Engineering and Risk Management (IJFERM):
Login with your Inderscience username and password:

Username:        Password:          Forgotten your password?

Want to subscribe?
A subscription gives you complete access to all articles in the current issue, as well as to all articles in the previous three years (where applicable). See our Orders page to subscribe.

If you still need assistance, please email subs@inderscience.com