“…The study of serial correlation of asset returns is particularly important in financial economics, since it can reveal basic features of the trading process. The Efficient Market Hypothesis in its weakest form implies that asset returns should be serially uncorrelated, but there is pervasive evidence of serial autocorrelation in stock index returns (Lo and MacKinlay, 1988;Poterba and Summers, 1988) and stock portfolios (Conrad and Kaul, 1988;Mech, 1993), mixed evidence on stocks (Lo and MacKinlay, 1990b;Conrad and Kaul, 1989;Kim et al, 1991) and international assets (Patro and Wu, 2004), mainly depending on volumes and size (Llorente et al, 2002), while stock index futures display no autocorrelation, see Ahn et al (2002) and Pan et al (1997) for currency futures. There are many theoretical models and explanations, on one side to reconcile the presence of serial correlation with a rational framework, e.g.…”