Permanent Open-Market Operations

A permanent open-market operation (or POMO) is an outright purchase or sale of a security by a central bank with no agreement to reverse it. Once the central bank buys a bond, it holds it until maturity—or until it later decides to sell—allowing the asset to permanently alter the size and composition of the central bank’s balance sheet.

The distinction from temporary operations

When the central bank conducts a temporary operation—a repurchase agreement or repo—it buys a security and simultaneously agrees to sell it back on a near-term date, usually overnight or a few days later. The operation is self-reversing; the balance sheet swells for a day and then contracts again.

A permanent operation is different. The central bank buys a security with no commitment to sell it back. It will hold the asset, collect interest on it, and let it run to maturity—or sell it later if circumstances warrant. The balance sheet grows, and it stays grown. If the central bank later decides to reduce its holdings, that requires an explicit decision to sell or (more commonly) to allow securities to mature without reinvesting the proceeds.

How POMOs shape policy

In ordinary times, when interest rates are well above zero, permanent operations are the workhorse. A central bank gradually buys securities to inject money and steer the federal funds rate toward its target, or sells securities to drain money and raise rates. Because these operations are continuous and ongoing, they give the central bank fine-tuned control over the overnight money supply.

The permanence of the operation distinguishes it from temporary fine-tuning. A temporary repo is a band-aid for a one-day cash shortage. A permanent purchase is a deliberate expansion of the money supply, reflecting a decision to run monetary policy more loosely for weeks, months, or years ahead.

POMOs and quantitative easing

When interest rates fall to zero and the central bank has exhausted the room to cut further, it often escalates from modest permanent operations to quantitative easing—a massive, sustained program of permanent purchases aimed at flooding the economy with money and pushing down longer-term interest rates.

During the 2008–2009 financial crisis, the Federal Reserve purchased over a trillion dollars in Treasury securities and mortgage-backed securities; these were permanent operations that fundamentally reshaped the central bank’s balance sheet. The assets were held for years, generating a sustained injection of money into the financial system.

POMOs and quantitative tightening

The inverse happens during tightening cycles. After years of large-scale permanent purchases, a central bank may decide to let its holdings runoff—that is, not reinvest the proceeds when securities mature. This is called balance-sheet runoff or quantitative tightening. It amounts to a permanent contraction of the balance sheet, draining money from the system.

For instance, after a decade of large holdings, the Federal Reserve may allow $200 billion in securities to mature each month and simply remove that money from circulation rather than buying new securities to replace them. That is a permanent reduction in the money supply, the inverse of permanent purchases.

The case for permanence

Permanent operations are transparent and powerful because their intent is unmistakable. When the central bank announces it will conduct large permanent purchases of bonds, markets understand that this is a deliberate expansion of the money supply, not a temporary patch. Expectations shift. Long-term interest rates often fall immediately, before the purchases even begin, because investors anticipate the effect on future policy.

The permanence also makes it harder for the central bank to back down. Once a permanent purchase is made, reversing it requires an explicit and visible decision to sell—which is politically and economically costly. This commitment device can actually strengthen the central bank’s hand. By conducting permanent purchases, the central bank credibly signals it is serious about easing, which can be more powerful than temporary operations.

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