Open Market Operations

Open market operations (OMOs) are the primary day-to-day instrument central banks use to implement monetary policy. By purchasing government bonds or other eligible securities from commercial banks, a central bank credits reserves to those banks, expanding the monetary base and putting downward pressure on short-term interest rates. By selling securities, it drains reserves and pushes rates upward. The mechanism allows the central bank to keep a policy rate — such as the U.S. federal funds rate or the euro area's deposit facility rate — close to its target.

OMOs are typically distinguished by purpose and tenor:

• Permanent (outright) operations alter the size of the central bank's balance sheet on a lasting basis. Large-scale asset purchases — commonly called quantitative easing (QE) — are an extension of this category, used by the U.S. Federal Reserve, Bank of England, Bank of Japan, and European Central Bank after the 2008 global financial crisis and again during the COVID-19 pandemic in 2020.
• Temporary operations include repurchase agreements (repos) and reverse repos, which inject or absorb liquidity for short periods, often overnight.

In the United States, OMOs are conducted by the Federal Reserve Bank of New York's trading desk under directives from the Federal Open Market Committee (FOMC), established by the Banking Act of 1935. The European Central Bank conducts its main refinancing operations weekly with eligible euro-area counterparties.

OMOs are generally preferred over blunter tools like changing reserve requirements because they are flexible, reversible, and market-based. Since 2008, however, many central banks have operated in an ample reserves regime, in which the policy rate is steered primarily through administered rates (such as interest on reserve balances) rather than through small reserve adjustments, changing the practical role of OMOs without eliminating them.

For IR and policy researchers, OMOs are central to debates over central bank independence, balance-sheet politics, and the spillovers of major-economy monetary policy onto emerging markets.