“…In the second case, which we adopt in this article, the intrinsic time is defined as a function of a latent intensity measure of the market's activity (Carr and Wu 2004). Empirically, the availability of HF data in the last two decades has opened great possibilities in estimating the intrinsic time directly from the intraday information, through specific choices of intensity measures, such as the trading volume (Mandelbrot and Taylor 1967;Clark 1973;Mandelbrot, Fisher, and Calvet 1997), the intraday volatility pattern (Zhou 1996;Dacorogna et al 2001;Oomen 2005Oomen , 2006; Peters and de Vilder 2006;Andersen, Bollerslev and Diebold 2007;Boudt, Croux, and Laurent 2011;Dong and Tse 2017), the intraday trading pattern (Dacorogna et al 1993;Ghysels, Gouriéroux, and Jasiak 1997;Ané and Geman 2000;Griffin and Oomen 2008;Wu 2012), or in the context of duration models (Engle and Russell 1998;Gerhard and Hautsch 2002). The applications of this approach have stretched from capturing the fat-tailedness of financial returns (Clark 1973;Mandelbrot, Fisher, and Calvet 1997;Marinelli et al 2000) to estimating their spot volatility (Dahlhaus and Tunyavetchakit 2016), RV (Oomen 2005(Oomen , 2006 and stochastic volatility (Tauchen and Pitts 1983;Ghysels, Gouriéroux, andJasiak 1997, 2004) as well as to measuring intraday leverage effects Andersen et al 2010) or for option pricing (Gouriéroux and Jasiak 2001).…”