| Abstract: | The first 150 words of the full text of this article appear below. During the 1980s, the early stages of modeling financial timeseries focused on the striking stylized fact that while returnswere themselves not serially correlated, squared returns were.This history has been nicely documented in the influential bookby Taylor (1986) and, indeed, the opening chapters of contemporaryfinancial econometrics open with Engle (1982) and Bollerslev(1986) who provided a specific ARMA structure of squared returnsvia the celebrated [G]ARCH models. This general orientationin effect acknowledged that there was some room for predictingrisk, as measured by squared values or absolute values of returns,while at the same time maintaining the hypothesis that returnsthemselves were hardly predictable in keeping with some versionof market efficiency. However, this paradigmatic view has beenchallenged over the subsequent 20 years in at least three regards. First, with Nelson (1991), it has been widely acknowledged thatalthough GARCH modeling is about . . . [Full Text of this Article] |
