Ten Isn’t Large! Group Size and Coordination in a Large-Scale Experiment

We provide experimental evidence on coordination within large groups that could proxy the atomistic nature of real-world markets. use a bank run game where two pure-strategy equilibria can be ranked by payoff and risk dominance sequence public announcements introduces stochastic sunspot equilibria. find systematic group size effects theory fails to predict. When payoff-dominant strategy is risky enough, behavior small uninformative in groups: unlike smaller ten, larger exclusively coordinate Pareto-inferior never sunspots. (JEL C92, D83, D91, G21)