Quantitative easing (QE)
Quantitative easing is when a central bank buys bonds on a large scale to push long-term interest rates lower.
When policy rates are already close to zero, a central bank can act another way: buying government or corporate bonds with newly created money. The Fed, the ECB, the BoE and the BoJ all used it heavily after 2008 and in 2020.
QE pushes yields down, supports risk assets and tends to weaken the currency concerned. Its opposite, quantitative tightening (QT), means shrinking the balance sheet by not reinvesting maturing bonds, or even selling them.
For a trader, announcements that change these programmes can have as much impact as a rate decision.