Endogenous Coalition Formation in Contests

This paper analyzes coalition formation in a model of contests with linear costs. Agents first form groups and then compete by investing resources. Coalitions fight for prizes that are assumed to be subject to rivalry, so their value is non-increasing in the size of the group. This formulation encompasses as particular cases some models proposed in the rent-seeking literature. We show that the formation of groups generates positive spillovers and analyze two classes of games of coalition formation. A contest among individual agents is the only stable outcome when individual defections leave the rest of the group intact. More concentrated coalition structures, including the grand coalition, are stable when groups collapse after a defection, provided that rivalry is not too strong. Results in a sequential game of coalition formation suggest that there exists a non-monotonic relationship between the level of underlying rivalry and the level of social conflict.