This paper presents and compares several time-series models for returns of broadbased stock indices. These models nest a nonlinear asymmetric GARCH (NGARCH) model as a special case. Some of these models are empirically motivated ad-hoc specifications others are derived from a representative...

We estimate the effects of R&D on firms' credit ratings and on financial distress. The main purpose is the comparison of firms in Western Germany and Eastern Germany as a transitional economy. Innovative activity has a positive impact on firm value proxied by ratings in Western Germany, but a...

This paper presents and compares several time-series models for returns of broadbased stock indices. These models nest a nonlinear asymmetric GARCH (NGARCH) model as a special case. Some of these models are empirically motivated ad-hoc specifications others are derived from a representative...