“…The application of nonparametric density estimators is widespread and growing in finance and financial econometrics. These estimators are often introduced to estimate transition densities (see Aït-Sahalia, 1996), the diffusion matrix (see Bandi and Moloche, 2017), state price densities (see Zhang et al, 2009;Song and Xiu, 2016;Beare and Schmidt, 2014), realized variance and stock volatilities (see Van Es, Spreij, and Zanten, 2003;Zu, 2015), implied volatilities (see Chen and Xu, 2014), as well as bond yields. In quantitative risk management, density estimates enable the calculation of risk measures, such as value-at-risk and expected shortfall (see Wang and Zhao, 2016;Cai and Wang, 2008;Opschoor, Dijk, and van der Wel, 2017).…”