Do short sellers outperformthe market?

Abstract

During the current financial crisis, short sellers have been blamed for causing or at least accelerating the crash of the financial market. They have been accused of manipulating stock prices so that they would fall and getting rich at the ‘naive’ investors' expense. This study investigates the validity of these accusations by following the TA100 Index and four designed portfolios during the period 2006 to 2008. The designed portfolios were constructed in accordance with the weekly report on short selling activity issued by the Tel Aviv Stock Exchange. The results show that short sellers did not succeed in outperforming the market during that 3-year period. Moreover, the portfolios that did not include the stocks picked by the short sellers performed more poorly (they should have been sold short) than the portfolios that included stocks chosen by the short sellers. These results contradict the hypothesis that short selling disrupts market efficiency.