The effects of insider trading on liquidity

This study examines the impacts of directors' dealings on firm liquidity. Consistent with the information asymmetry hypothesis, spread widens and depth falls on insider trading days as compared to non-insider trading days. This result suggests that increased share trading by insiders impairs liquidity. In addition, the spread (depth) measures are positively (negatively) related to how heavily the shares are transacted by informed traders; that is, the greater the number of shares traded by the directors, the wider (narrower) the spread (depth).