Transactions Volume, Exchange Direction and Asymmetry of Volatility in Emerging Market: Evidence From Tunisian Stock Exchange

Abstract

This study is an attempt to explain the relationship between intraday return and volume in Tunisian Stock Market. Indeed, former researches avow that the trading activity have the main explanatory power for volatility. However, most theories measure the activity of transactions through the size of exchange or the number of transactions. Nevertheless, these components are not aware enough of the importance of the direction of exchange when explaining the phenomenon of asymmetry of volatility. In the most of studies, the technique “Augmented Tick Test” (ATT) is employed so as to identify the direction of exchange. Such technique is adapted for the markets directed by orders like the Tunisian financial market. Again, this paper shows that the impact of the direction of exchange differs according to the market trend. In other words, if the returns are positive, the transactions of sale (of purchase) generate a decrease (increase) of volatility; whereas, they induce an increase (drop) of volatility if returns are negative. This result stresses the significance of exchange direction in explaning the asymmetry of volatility. Moreover, throughout this study, one may affirm that “Herding trades” are at the origin of the increase of volatility, while the “Contrarian trades” reduce volatility. Similarly, the identification of the direction of exchange enables us to affirm that the transactions of the initiates are characterized by the absence of returns auto- correlation; whereas, the transactions carried out by uninformed investors present an auto- correlation of the returns. In fact, the sign of this correlation varies according to transaction direction.