Assessment of market efficiency in Argentina, Brazil and Chile: an event study of mergers and acquisitions

this paper presents an investigation into the relationship between the announcement of mergers and acquisitions, the existence of positive abnormal returns for shares of these firms, and market efficiency in argentina, brazil and chile. statistically significant standardized abnormal returns were present in the event announcement and the following days in argentina and chile and on the event day in brazil, confirming value creation signaling. furthermore, the significance of abnormal returns in the event window, namely in the 5 days following the event in argentina and chile and the absence of such in brazil suggests a more efficient market exists in brazil, in keeping with the semi-strong market efficiency hypothesis. the absence of semi-strong efficient market behavior could prove valuable to investors who could use a window of a few days after the event announcement to accumulate abnormal returns, provided the appropriate research into news of possible mergers or acquisitions has been made.