In the context of Merton [1974] and Vasicek [1987, 2002] Gaussian single-factor credit risk models, the authors examine the impact of neglected non-normality of the underlying asset return process on the shape of the derived credit loss distribution and the resulting Basel capital requirements....

Assuming the time series of random returns to be jointly elliptical, we derive a relationship between its conditional variance and the probability density function of the conditioning set. In the case that such a relationship is linear in a quadratic form for of the conditioning variables, we...