There is considerable controversy over why sluggish economic growth persists across many advanced economies six years after the onset of the financial crisis. Theories include a secular deficiency in aggregate demand, slowing innovation, adverse demographics, lingering policy uncertainty,...

We extend the basic (representative-household) New Keynesian [NK] model of the monetary transmission mechanism to allow for a spread between the interest rate available to savers and borrowers, that can vary for either exogenous or endogenous reasons. We find that the mere existence of a...