How is Cooperation/collusion Sustained in Repeated Multimarket Contact with Observation Errors?

This paper analyzes repeated multimarket contact with observation errors where two players operate in multiple markets simultaneously. Multimarket contact has received much attention in economics, management, and so on. Despite vast empirical studies that examine whether multimarket contact fosters cooperation or collusion, little is theoretically known as to how players behave in an equilibrium when each player receives a noisy and different observation or signal indicating other firms' actions (private monitoring). To the best of our knowledge, we are the first to construct a strategy designed for multiple markets whose per-market equilibrium payoffs exceed one for a single market, in our setting. We first construct an entirely novel strategy whose behavior is specified by a non-linear function of the signal configurations. We then show that the per-market equilibrium payoff improves when the number of markets is sufficiently large.