The persistent nature of equity volatility is investigated by means of a multi-factor stochastic volatility model with time varying parameters. The parameters are estimated by means of a sequential matching procedure which adopts as auxiliary model a time-varying generalization of the HAR model...

We study the theoretical and empirical properties of a simple measure of market illiquidity, namely the realized Amihud, which is defined as the ratio between the realized volatility and trading volume and which refines the popular price impact measure proposed by Amihud (2002). In our model,...