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Quantitative easing and tightening

You can explain how quantitative easing and tightening work, why central banks use them, and read the Fed's balance sheet history.

When rates hit zero

In December 2008, the Fed cut its policy rate to a range of 0% to 0.25%. The economy was in its deepest downturn since the Great Depression, and the usual tool was used up. A policy rate cannot go much below zero.

So the Fed reached for a different tool. It started buying bonds, on a scale never seen before. Over the following years, other central banks did the same. This lesson explains how that works, how it is reversed, and why its effects are still debated.

Buy bonds, lower yields

In quantitative easing (QE), a central bank buys large amounts of bonds, mainly government bonds and, in the US, mortgage-backed securities. It pays by creating new reserves, the money banks hold at the central bank.

The intended effects:

Lower long-term yields. Large purchases raise bond prices and push down yields, which also lowers mortgage and corporate borrowing costs.
Portfolio rebalancing. Investors who sold bonds to the central bank buy other assets, often riskier ones, which can lift share prices.
A signal. Buying bonds for years shows that the central bank intends to keep policy loose.

Quantitative tightening (QT) reverses this. The Fed has done it mainly by letting bonds mature without reinvesting the proceeds, up to monthly caps, so the balance sheet shrinks gradually rather than through sales.

QE is often described as "printing money", but that is misleading. The new reserves stay inside the banking system. Whether they lead to more lending and spending depends on banks and borrowers.

From 0.9 to almost 9 trillion

The Fed's weekly H.4.1 release shows its total assets:

Before the crisis: 0.87 trillion dollars in August 2007.
Three rounds of QE, 2008 to 2014: 4.51 trillion at the end of 2014.
First QT, 2017 to 2019: down to 4.08 trillion at the end of 2018.
Pandemic QE, 2020 to 2021: 8.76 trillion at the end of 2021. The weekly peak, 8.97 trillion, came in April 2022.
Second QT, from June 2022: down to 6.58 trillion at the end of 2025. The Fed ended the reduction on 1 December 2025.

Research generally finds that QE announcements lowered long-term yields, but estimates of the size, and of the effect on inflation and share prices, vary widely.

Common mistakes

Equating QE with cash for shops. The new money is bank reserves, not banknotes handed to households.
Watching only the policy rate. Balance sheet decisions can move long-term yields on their own.
Assuming QT is the exact mirror of QE. Letting bonds run off slowly is not the same as buying them quickly.
Treating the effects as settled. Economists still disagree on how much QE did.

The takeaway

With quantitative easing, a central bank buys bonds to push long-term rates down. Quantitative tightening lets them run off. Both move markets indirectly.

Check yourself

Quick quiz

4 questions. Instant feedback, nothing is saved.

1Tap the year-end with the largest Fed balance sheet.

Tap the chart.

At the end of 2021, the Fed held 8.76 trillion dollars of assets. The weekly peak, 8.97 trillion, came in April 2022.
2What does a central bank do in quantitative easing?

QE expands the central bank's balance sheet. The aim is to push down long-term yields when the policy rate is already near zero.
3How did the Fed run quantitative tightening from June 2022?

Passive roll-off shrank the balance sheet gradually. The Fed ended the reduction on 1 December 2025.
4Why is the effect of QE on markets hard to measure?

Researchers find effects on yields, especially at announcements, but disagree on how large they are.

of 4 correct.

Sources