052<p type="texpara" tag="Body Text" et="abstract" >This paper proposes an explanation of merger waves based on a dynamic preemption game. A set of acquirers compete over time for scarce targets. At each point in time, an acquirer can either postpone a takeover attempt, or raid immediately. By postponing the takeover, an acquirer may gain from more favourable future market conditions, but runs the risk of being preempted by rivals. I first consider a complete information model and show that the above tradeoff leads to a continuum of subgame perfect equilibria. All equilibria share the feature that all acquiring firms rush simultaneously in merger waves. The model is then extended to a dynamic global game by introducing slightly noisy private information about merger profitability. This game is shown to have a unique perfect Bayesian equilibrium. The comparative dynamics predictions of the model are related to empirical findings.