Modeling Long Memory and Structural Breaks in Conditional Variances: An Adaptive FIGARCH Approach

This paper introduces a new long memory volatility process, denoted by Adaptive <i>FIGARCH</i>, or <i>A-FIGARCH</i>, which is designed to account for both long memory and structural change in the conditional variance process. Structural change is modeled by allowing the intercept to follow a slowly varying function, specified by Gallant (1984)'s flexible functional form. A Monte Carlo study finds that the <i>A-FIGARCH</i> model outperforms the standard <i>FIGARCH</i> model when structural change is present, and performs at least as well in the absence of structural instability. An empirical application to stock market volatility is also included to illustrate the usefulness of the technique.