IDEAS home Printed from
MyIDEAS: Log in (now much improved!) to save this article

Confidence sets for asset correlations in portfolio credit risk

Listed author(s):
  • Carlos Castro


Abstract:Asset correlations are of critical importance in quantifying portfolio credit risk and economic capital in financial institutions. Estimation of asset correlation with rating transition data has focused on the point estimation of the correlation without giving any consideration to the uncertainty around these point estimates. In this article we use Bayesian methods to estimate a dynamic factor model for default risk using rating data (McNeil et al., 2005; McNeil and Wendin, 2007).Bayesian methods allow us to formally incorporate human judgement in the estimation of assetcorrelation, through the prior distribution and fully characterize a confidence set for the correlations.Results indicate: i) a two factor model rather than the one factor model, as proposed bythe Basel II framework, better represents the historical default data. ii) importance of unobservedfactors in this type of models is reinforced and point out that the levels of the implied asset correlations critically depend on the latent state variable used to capture the dynamics of default,as well as other assumptions on the statistical model. iii) the posterior distributions of the assetcorrelations show that the Basel recommended bounds, for this parameter, undermine the levelof systemic risk.Resumen:Las correlaciones entre los activos de un portafolio crediticio, son parámetros de suma importanciapara la estimación del riesgo crediticio y capital económico de una institución financiera.La literatura especializada en la estimación de las correlaciones entre los activos, que utiliza información de migraciones entre las calificaciones de riesgo, se ha concentrado principalmenteen la estimación puntual de los parámetros, desconociendo la incertidumbre alrededor del estimadorpuntual. En este articulo utilizamos métodos bayesianos para estimar el modelo factorialdinámico para riesgo de quiebra utilizando datos de calificaciones de riesgo sobre un portafoliocrediticio (McNeil et al., 2005; McNeil andWendin, 2007). Los métodos bayesianos nos permiten:incorporar formalmente la información experta en el proceso de estimación de las correlacionesmediante la distribución a priori y obtener intervalos de confianza alrededor de los parámetrosde interés. Los resultados indican: i) un modelo de dos factores se ajusta mejor a la informaciónhistórica de quiebras, que el modelo de un factor (recomendado en Basilea II), ii) resalta la importancia de la introducción de factores no-observables en la especificación del modelo, en particular, las propiedades estadísticas de los factores no-observables puede tener un efecto importante sobre la magnitud de las correlaciones estimadas, iii) las distribuciones a posteriori de las correlaciones entre los activos indican que los intervalos sugeridos por el documento de Basileasubestiman el riesgo sistémico.

If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.

File URL:
Download Restriction: no


Volume (Year): (2012)
Issue (Month): (June)

in new window

Handle: RePEc:col:000151:009911
Contact details of provider:

References listed on IDEAS
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:

in new window

  1. McNeil, Alexander J. & Wendin, Jonathan P., 2007. "Bayesian inference for generalized linear mixed models of portfolio credit risk," Journal of Empirical Finance, Elsevier, vol. 14(2), pages 131-149, March.
  2. Koopman, Siem Jan & Kräussl, Roman & Lucas, André & Monteiro, André B., 2009. "Credit cycles and macro fundamentals," Journal of Empirical Finance, Elsevier, vol. 16(1), pages 42-54, January.
  3. Merton, Robert C, 1974. "On the Pricing of Corporate Debt: The Risk Structure of Interest Rates," Journal of Finance, American Finance Association, vol. 29(2), pages 449-470, May.
  4. Sanjiv R. Das & Darrell Duffie & Nikunj Kapadia & Leandro Saita, 2007. "Common Failings: How Corporate Defaults Are Correlated," Journal of Finance, American Finance Association, vol. 62(1), pages 93-117, 02.
  5. Nickell, Pamela & Perraudin, William & Varotto, Simone, 2000. "Stability of rating transitions," Journal of Banking & Finance, Elsevier, vol. 24(1-2), pages 203-227, January.
  6. Koopman, Siem Jan & Lucas, André, 2008. "A Non-Gaussian Panel Time Series Model for Estimating and Decomposing Default Risk," Journal of Business & Economic Statistics, American Statistical Association, vol. 26, pages 510-525.
  7. Bangia, Anil & Diebold, Francis X. & Kronimus, Andre & Schagen, Christian & Schuermann, Til, 2002. "Ratings migration and the business cycle, with application to credit portfolio stress testing," Journal of Banking & Finance, Elsevier, vol. 26(2-3), pages 445-474, March.
Full references (including those not matched with items on IDEAS)

This item is not listed on Wikipedia, on a reading list or among the top items on IDEAS.

When requesting a correction, please mention this item's handle: RePEc:col:000151:009911. See general information about how to correct material in RePEc.

For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Facultad de Economía)

If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

If references are entirely missing, you can add them using this form.

If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.

If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.

Please note that corrections may take a couple of weeks to filter through the various RePEc services.

This information is provided to you by IDEAS at the Research Division of the Federal Reserve Bank of St. Louis using RePEc data.