Impact of the Self-Attribution Bias on the Trading Activity: The Case of the Tunisian Stock Market

Abstract

The self-attribution bias is the tendency of people to consider themselves as able to influence randomly-generated outcomes. Investors who exhibit such a bias tend to attribute market gains to their ability to select winning stocks and trade actively in the subsequent period. We examined this hypothesis in the Tunisian stock market before and after the 2011 revolution using a causality test between market trading volume and market return. We found that Tunisian investors tend to trade more after observing high market returns and trade less after poor market performance. In the wake of the Tunisian revolution, this effect persists for one-week horizon, but disappears for one-month horizon.