Mergers and acquisitions continue to be value destroying for many acquiring firm shareholders. Lack of continuity of tenure, agency problems and animal spirits in the acquiring and acquired firms may contribute to this loss of value. This study examines acquisitions in Australia between 1990 and 2006, when the roles of chairman and chief executive were performed by different people in the acquiring firm. The study finds that the period of joint tenure, when the Chairman and CEO have been in their respective roles together, is a statistically significant contributor to acquiring firm shareholder value during the three year period following completion of the acquisition. Agency problems and animal spirits are also found to be important influences on M&A outcomes.