Designing QE to overcome the lower bound constraint on interest rates in a fiscally sound monetary union

This paper develops a model of a fiscally sound monetary union and analyses central bank purchases of long-term debt (QE). Employing the portfolio balance channel, we show that there exists an interest rate rule augmented by QE at the lower bound which replicates the equilibrium allocation and the welfare level of a hypothetically unconstrained economy. We show further that the symmetry of QE depends on whether the monetary union is characterised by asymmetric shocks or asymmetric structures.