Open market operation

In macroeconomics, an open market operation (OMO) is an activity by a central bank to exchange liquidity in its currency with a bank or a group of banks. The central bank can either transact government bonds and other financial assets in the open market or enter into a repurchase agreement or secured lending transaction with a commercial bank. The latter option, often preferred by central banks, involves them making fixed period deposits at commercial banks with the security of eligible assets as collateral.

Central banks regularly use OMOs as one of their tools for implementing monetary policy. A frequent aim of open market operations is — aside from supplying commercial banks with liquidity and sometimes taking surplus liquidity from commercial banks — to influence the short-term interest rate. Open market operations have become less prominent in this respect since the 2008 financial crisis, however, as many central banks have changed their monetary policy implementation to a so-called floor system (or system of ample reserves), in which there is abundant liquidity in the payments system. In that situation central banks no longer need to fine tune the supply of reserves to meet demand, implying that they may conduct OMOs less frequently. For countries operating under an exchange rate anchor, direct intervention in the foreign exchange market, which is a specific type of open market operations, may be an important tool to maintain the desired exchange rate.

In the post-crisis economy, conventional short-term open market operations have been superseded by major central banks by quantitative easing (QE) programmes. QE are technically similar to open-market operations, but entail a pre-commitment of the central bank to conduct purchases to a predefined large volume and for a predefined period of time.