Block reward halves from 12.5 BTC to 6.25 BTC at block 630,000 on May 11, 2020. Occurred during the COVID-19 pandemic with Bitcoin trading around $8,600 -- and just weeks after the March 2020 crash had briefly taken BTC below $4,000. The third halving reduced Bitcoin's annual inflation rate to approximately 1.8%, below the Federal Reserve's 2% target. With central banks printing trillions in stimulus worldwide, Bitcoin's predetermined scarcity schedule had never looked more relevant. A rally to $64,000 followed within a year.
Bitcoin Wiki: Controlled supply