Evidence for Some Underlying Time Series Momentum

The chapter documents significant and momentary momentum pattern in stock returns times series. Moreover, the chapter gives evidence that this time series momentum is the main driver of the cross-sectional momentum pattern. The temporary time series momentum pattern is midway between the behavioural and rational financial theories. Given the strong and positive autocorrelation in stock returns time series, the authors argue that investors are temporary under reacting, and they progressively find their full rationality. Using monthly returns inherent to all stocks listed on Tunisian stock market, from January 2000 to December 2009, the authors examine momentum strategy's excess returns before and after considering time series momentum in stocks returns. Results show that momentum strategy is still profitable, but no longer puzzling. Furthermore, the chapter aims to reconcile between the behavioural and the rational financial theories, through the introduction of the progressive investors rationality.