Estimating Probabilities of Default for Low Default Portfolios
- 1 December 2004
- preprint
- Published by Elsevier BV in SSRN Electronic Journal
Abstract
For credit risk management purposes in general, and for allocation of regulatory capital by banks in particular (Basel II), numerical assessments of the credit-worthiness of borrowers are indispensable. These assessments are expressed in terms of probabilities of default (PD) that should incorporate a certain degree of conservatism in order to reflect the prudential risk management style banks are required to apply. In case of credit portfolios that did not at all suffer defaults or very few defaults only over years, the resulting naive zero or close to zero estimates would clearly not involve a sufficient conservatism. As an attempt to overcome this issue, we suggest the most prudent estimation principle. This means to estimate the PDs by upper confidence bounds while guaranteeing at the same time a PD ordering that respects the differences in credit quality indicated by the rating grades. The methodology is most easily applied under an assumption of independent default events but can be adapted to the case of correlated defaults without too much effort.Keywords
Other Versions
This publication has 4 references indexed in Scilit:
- Measurement, estimation and comparison of credit migration matricesJournal of Banking & Finance, 2004
- A risk-factor model foundation for ratings-based bank capital rulesJournal of Financial Intermediation, 2003
- An Introduction to Credit Risk ModelingPublished by Informa UK Limited ,2002
- Interval Estimation for a Binomial ProportionStatistical Science, 2001