Efficient Estimation of a Multivariate Multiplicative Volatility Model

We propose a multivariate generalization of the multiplicative volatility model ofEngle and Rangel (2008), which has a nonparametric long run component and aunit multivariate GARCH short run dynamic component. We suggest variouskernel-based estimation procedures for the parametric and nonparametriccomponents, and derive the asymptotic properties thereof. For the parametric partof the model, we obtain the semiparametric efficiency bound. Our method isapplied to a bivariate stock index series. We find that the univariate model of Engleand Rangel (2008) appears to be violated in the data whereas our multivariatemodel is more consistent with the data.