Liquidity trap

A liquidity trap is a situation, described in Keynesian economics, in which injections of cash into the private banking system by a central bank fail to decrease interest rates and hence make monetary policy ineffective. A liquidity trap is caused when people hoard cash because they expect an adverse event such as deflation, insufficient aggregate demand, or war. Common characteristics of a liquidity trap are interest rates that are close to zero and fluctuations in the money supply that fail to translate into fluctuations in price levels.

Conceptual evolution

In its original conception, a liquidity trap refers to the phenomenon when increased money supply fails to lower interest rates. Usually central banks try to lower interest rates by buying bonds with newly created cash. In a liquidity trap, bonds pay little or no interest, which makes them nearly equivalent to cash. Under the narrow version of Keynesian theory in which this arises, it is specified that monetary policy affects the economy only through its effect on interest rates. Thus, if an economy enters a liquidity trap, further increases in the money stock will fail to further lower interest rates and, therefore, fail to stimulate.