Optimal Stabilization Policy with Search Externalities

We study optimal monetary stabilization policy in a DSGE model with microfounded money demand. A search externality creates ‘congestion’ which causes aggregate output to be inefficient. Due to the informational frictions that give rise to money, households are unable to perfectly insure themselves against aggregate shocks. This gives rise to a welfare improving role for monetary policy that works by adjusting the nominal interest rate in response to these shocks. Optimal policy is determined by choosing a set of state-contingent nominal interest rates to maximize the expected lifetime utility of the agents subject to the constraints of being an equilibrium.