What Do We Know about Success and Failure of Mergers?

Collecting the most important results of about 80 empirical merger studies, this study condenses the bewildering spectrum of results to 18 stylized facts. Most important, no more than a quarter of the mergers increase consumer welfare; another quarter increase profits at the cost of consumers; half of the mergers reduce the value of the firm. Targets' shareholders win, while bidders' shareholders break even upon the announcement of a merger, but lose significantly in the long run. Seen relatively, horizontal mergers fare best, especially if they are focus-increasing. Cash-financed mergers fare better than stock-financed and strategic mergers fare better than financial ones. Confronting the stylized facts with existing merger theory reveals some major paradoxes; confronting them with existing competition policy reveals the need for a modification and intensification, as mergers increase concentration, and corporate policy strives towards still higher concentration. As a summary ten lessons are extracted on what we may have learnt, and on what is still open.