Stats › Best and worst days › Black Monday 1987

The S&P 500 fell 20.47% in one day and nobody knows why

19 Oct 1987: -20.47%-20.47%19 Oct198728 Oct 1929: -12.34%-12.34%28 Oct192916 Mar 2020: -11.98%-11.98%16 Mar202029 Oct 1929: -10.16%-10.16%29 Oct192906 Nov 1929: -9.92%-9.92%06 Nov1929

The gap between first and second is larger than the gap between second and fifteenth. Nothing in 2008 or 2020 approached it. Source: Wikipedia, largest daily changes in the S&P 500 Index.

On 19 October 1987 the S&P 500 fell 20.47% and the Dow 22.61%, still the largest single day declines on record. No bank failed, no war began, no policy changed that morning. The explanations that survive are about market plumbing rather than the economy.

-20.47%S&P 500, 19 Oct 1987
-22.61%Dow, same day
-12.34%Second worst S&P day
+9.10%Two days later

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