We analyze portfolio credit risk in light of dynamic quot;frailty,quot; by which the credit qualities of different firms depend on common unobservable time-varying default covariates. Frailty is estimated to have a large impact on estimated conditional mean default rates, above and beyond those...

We assume that the instantaneous riskless rate reverts toward a central tendency which, in turn, is changing stochastically over time. As a result, current short-term rates are not sufficient to predict future short- term rate movements, as it would be the case if the central tendency were...