Informational Puts

We fully characterize how dynamic information should be provided to uniquely implement the largest equilibrium in dynamic binary-action supermodular games. The designer offers an informational put: she stays silent in good times, but injects asymmetric and inconclusive public information if players lose faith. There is (i) no multiplicity gap: the largest (partially) implementable equilibrium can be implemented uniquely; and (ii) no intertemporal commitment gap: the policy is sequentially optimal. Our results have sharp implications for the design of policy in coordination environments.