Filbien and Kooli find (not surprisingly) that takeovers are bad for the pother firms in the industry.
"We examine the wealth creation for acquiring and target firms' shareholders to Canadian merger and acquisition announcements. We also investigate the potential determinants of the stock market reactions. Further, we explore the impact of these announcements on the gains of the target firms' rivals. Takeovers are beneficial to the shareholders of merging firms. However, we show that Canadian rival firms lose abnormal returns"