Rating downgrades are known to make subsequent downgrades more likely. We analyze the impact of this 'downward momentum' on credit portfolio risk. Using S&P ratings from 1996 to 2005, we estimate a transition matrix that is insensitive to and a second matrix that is sensitive to previous...

This paper extends the family of smooth transition autoregressive (STAR) models by proposing a speci.cation in which the autoregressive parameters follow random walks. The random walks in the parameters capture permanent structural change within a regime switching framework, but in contrast to...

Measuring and displaying uncertainty around path-forecasts, i.e. forecasts made in period T about the expected trajectory of a random variable in periods T+1 to T+H is a key ingredient for decision making under uncertainty. The probabilistic assessment about the set of possible trajectories that...