RT Report T1 Asymmetry and Long Memory in Volatility Modelling A1 Asai, Manabu A1 McAleer, Michael A1 Medeiros, Marcelo C. AB A wide variety of conditional and stochastic variance models has been used to estimate latent volatility (or risk). In this paper, we propose a new long memory asymmetric volatility model which captures more flexible asymmetric patterns as compared with several existing models. We extend the new specification to realized volatility by taking account of measurement errors, and use the Efficient Importance Sampling technique to estimate the model. As an empirical example, we apply the new model to the realized volatility of S&P500 to show that the new specification of asymmetry significantly improves the goodness of fit, and that the out-of-sample forecasts and Value-at-Risk (VaR) thresholds are satisfactory. Overall, the results of the out-of-sample forecasts show the adequacy of the new asymmetric and long memory volatility model for the period including the global financial crisis. YR 2011 FD 2011-08 LK https://hdl.handle.net/20.500.14352/49024 UL https://hdl.handle.net/20.500.14352/49024 LA eng NO The authors are most grateful to a Co-Editor, Associate Editor and two referees for very helpful comments and suggestions, and Marcel Scharth for efficient research assistance. NO Japan Society for the Promotion of Science NO Japan Ministry of Education Culture, Sports, Science and Technology NO Australian Academy of Science NO Australian Research Council, NO National Science Council NO Taiwan, and Japan Society for the Promotion of Science NO CNPq, Brazil DS Docta Complutense RD 11 abr 2025