The Liquidity-Augmented Model of Macroeconomic Aggregates

We propose a new model of the macroeconomy which is simple and tractable, yet explicit about the foundations of liquidity. Monetary policy is implemented via swaps of money for liquid bonds in a secondary asset market, and these have real effects because money, bonds, and capital are imperfect substitutes. The model unifies two classical channels through which the price of liquidity affects the economy (Friedman’s real balance effect vs Mundell’s and Tobin’s asset substitution effect), and it shines light on important macroeconomic questions: optimal monetary policy in the long run, the causal link between interest rates and inflation, and the existence and persistence of a liquidity trap where interest rates are zero but inflation is positive.