Central Bank Balance Sheet

A central bank’s balance sheet is an X-ray of how much monetary stimulus is flowing into the economy and how much risk the central bank has taken on. When the Federal Reserve expands its balance sheet from $900 billion to $4 trillion (as it did during the 2008 crisis), it is signaling massive monetary stimulus and accepting enormous amounts of risky assets. Reading a central bank balance sheet is essential to understanding monetary policy in practice.

Assets: what the central bank owns

The asset side of a central bank’s balance sheet shows what it has purchased or lent:

Government Bonds: The Federal Reserve holds vast quantities of U.S. Treasury bonds and mortgage-backed securities issued or guaranteed by government-sponsored enterprises. When the Fed buys Treasuries, it is injecting money into the economy and pushing down long-term interest rates. As of 2024, the Fed holds roughly $4 trillion in securities.

Loans to Banks: In normal times, the Federal Reserve makes loans to banks through the discount window. In crises, it creates special lending facilities (like the Primary Dealer Credit Facility or the Commercial Paper Funding Facility) and loans expand sharply.

Foreign exchange reserves: Some central banks (particularly those managing currencies with fixed or managed exchange rates) hold large quantities of foreign currencies and foreign government bonds to intervene in currency markets.

The riskier the assets on the balance sheet, the more monetary policy stimulus is flowing in, but also the more risk the central bank is taking.

Liabilities: what the central bank owes

Currency in circulation: Paper money (bills and coins) is a liability of the central bank. The Fed owes the holder of a $100 bill whatever that bill can buy. It is a zero-interest rate liability.

Bank reserves: When the Federal Reserve credits a bank’s reserve account (either by buying securities or lending), it has created a liability — the bank can withdraw that cash anytime. Since 2008, bank reserves have grown from about $100 billion to trillions. These reserves pay interest (on excess reserves), so they are not zero-cost liabilities.

Other deposits: The Fed holds deposits from the U.S. Treasury and certain financial institutions.

The larger the balance sheet, and the more of it is in the form of reserves (which earn interest), the more expensive it is to operate the central bank.

The balance sheet expansion: 2008 and 2020

In September 2008, when Lehman Brothers collapsed and credit markets froze, the Federal Reserve began expanding its balance sheet aggressively. It bought commercial paper, mortgage-backed securities, and Treasury bonds, and created lending facilities. Within six months, the Fed’s balance sheet more than tripled, from under $900 billion to $2 trillion. This was quantitative easing — monetary stimulus by balance-sheet expansion.

The same happened in March 2020 when COVID-19 triggered a credit freeze. The Fed expanded its balance sheet to $7.3 trillion within weeks, buying everything from Treasury bonds to corporate bonds to municipal bonds. The speed and scale were unprecedented.

The balance-sheet shrinkage: quantitative tightening

After quantitative easing, the Federal Reserve must eventually shrink its balance sheet to normalize monetary policy. This process is called “quantitative tightening” or QT. The Fed stops reinvesting the proceeds from maturing bonds, or actively sells bonds, which drains reserves from the banking system and tightens financial conditions.

The Fed began QT in 2015 and shrank its balance sheet modestly until COVID hit and the program reversed. The Fed then began QT again in September 2022, but the process is slow and controversial. Banks argue that shrinking the balance sheet too fast can trigger financial stress (as happened in March 2023 when several regional banks failed).

The monetary base and the balance sheet

The Fed’s balance sheet is intimately connected to the monetary base — the money the Fed directly controls. When the Fed expands its balance sheet, it increases the monetary base, which banks can then lend out through the money multiplier. When the Fed shrinks its balance sheet, the monetary base shrinks.

Central bank profits and losses

Central banks typically run at a profit, collecting seigniorage (the gain from issuing currency) and interest income from their asset holdings. But a central bank can also run losses. If bond prices fall sharply (because interest rates rise), the market value of the Fed’s holdings falls. If the Fed bought a bond for $100 and rates rise, the bond might be worth only $90 in the market. The Fed usually does not mark-to-market its holdings, so these losses do not show up on the official balance sheet. But if the Fed were forced to sell assets at a loss, or if it shrank its balance sheet while taking market losses, it could become insolvent.

This happened to the Fed (briefly) in 2024. As interest rates rose to fight inflation, the market value of the Fed’s bond holdings fell by hundreds of billions. The Fed reported unrealized losses for the first time in decades. This forced a conversation about whether a central bank should mark its assets to market and whether the Fed could ever truly run an accounting loss.

Different central banks, different balance sheets

The Federal Reserve’s balance sheet is large (about $7 trillion in 2023, or 25% of U.S. GDP), but the Bank of Japan’s is even larger relative to GDP (over 130% of Japanese GDP). The ECB’s is about 55% of eurozone GDP. These differences reflect how much monetary stimulus each central bank has deployed and how long it has persisted. The BoJ’s huge balance sheet reflects three decades of quantitative easing in response to deflation and weak growth.