A dynamic leverage stochastic volatility model

Abstract

Stock returns are considered as a convolution of two random processes that are the return innovation and volatility innovation. The correlation of these two processes tends to be negative, which is the so-called leverage effect. In this study, we propose a dynamic leverage stochastic volatility (DLSV) model where the correlation structure between the return innovation and the volatility innovation is assumed to follow a generalized autoregressive score (GAS) process. We find that the leverage effect is reinforced in the market downturn period and weakened in the market upturn period.