A parsimonious extension of a well-known portfolio credit-risk model allows us to study a salient stylized fact - abrupt switches between high- and low-loss phases - from a risk-management perspective. As uncertainty about phase switches increases, expected losses decouple from unexpected...

Extending a standard credit-risk model illustrates that a single factor can drive both expected losses and the extent to which they may be exceeded in extreme scenarios, ie "unexpected losses." This leads us to develop a framework for forecasting these losses jointly. In an application to...