In this paper we propose a simple, automatic insurance mechanism designed to cope with asymmetric shocks in a monetary union, which could be used as starting point of a more elaborated policy instrument. The mechanism would use as indicator of the occurrence of a shock the changes in the unemployment rate of the countries belonging to the union, and would be financed through a fund built from contributions of these countries as a percentage of their tax receipts. The fund would be distributed among the countries affected by a negative asymmetric shock according to the proportion in which every one of them would have been affected by the shock. Our proposal is illustrated by means of an empirical application to the case of EMU.