Managing Credit Bubbles

The "equilibrium" bubble size depends on investor sentiment, however, and it typically does not coincide with the "optimal" bubble size. This provides a new rationale for macroprudential policy. A lender of last resort can replicate the "optimal" bubble by taxing credit when the "equilibrium" bubble is too high, and subsidizing credit when the "equilibrium" bubble is too low. This leaning-against-the-wind policy maximizes output and consumption. Moreover, the same conditions that make this policy desirable guarantee that a lender of last resort has the resources to implement it