Modeling volatility persistence of speculative returns: A new approach

This paper extends the work by Ding, Granger, and Engle (1993) and further examines the long memory property for various speculative returns. The long memory property found for S&P 500 returns is also found to exist for four other different speculative returns. One significant difference is that for foreign exchange rate returns, this property is strongest when d = 1/4 instead of at d = 1 for stock returns. The theoretical autocorrelation functions for various GARCH (1,1) models are also derived and found to be exponentially decreasing, which is rather different from the sample autocorrelation function for the real data. A general class of long memory models that has no memory in returns themselves but long memory in absolute returns and their power transformations is proposed. The issue of estimation and simulation for this class of models is discussed. The Monte Carlo simulation shows that the theoretical model can mimic the stylized empirical facts strikingly well.