A study on volatility spurious almost integration effect: A threshold realized GARCH approach

Abstract

This paper investigates the "spurious almost integration" effect of volatility under a threshold GARCH structure with realized volatility measures. To closely examine the effect, the realized persistence of volatility is proposed to be used as a threshold trigger for volatility regimes. Under the threshold framework, general closed-form solutions of moment conditions are derived, which provide a convenient way to theoretically examine the "spurious almost integration" effect and its associated impacts. We find that introducing the volatility persistence-driven threshold can capture regime-specific characteristics well. It performs better than the traditional GARCH-type models in terms of both in-sample fitting and out-of-sample forecasting. Based on our Monte Carlo and empirical results, in general we find that overlooking the relatively low persistence regime(s) could lead to some misleading conclusions.