March 12, 2020, marked the largest one-day percentage fall in the FTSE 100 during the 2020 COVID-19 crash.
The London index dropped 10.87% as investors reacted to rapidly spreading coronavirus infections, travel restrictions, and evidence of a global economic shutdown. It was the FTSE 100's biggest one-day percentage decline since the 1987 crash. Markets worldwide experienced extraordinary volatility that month.
Central banks cut interest rates and governments announced fiscal support, but uncertainty remained high. A second severe FTSE 100 decline came on March 16, when the index fell about 10.87% again by some measures, while other calculations record March 12 as the sharper percentage move depending on closing data conventions.
The 2020 crash differed from earlier crises because a public-health emergency directly halted economic activity. Markets began recovering after policy support and vaccine developments later in the year.