Risk Sharing in a Federation with Population Mobility and Long Horizons

This paper considers risk sharing among individuals within and across regions in a federation with population mobility and infinite horizons. It is shown that the regional authorities will not fully exploit gains from inter-regional risk sharing when population mobility is imperfect. However, in the Nash equilibrium there is complete risk sharing among the individuals within each region, which corresponds to the policies of the central authority. Regional authorities who care about their reputation may be able to commit to an efficient allocation. It is possible that improvements in the degree of mobility will make such commitments less likely.