The 1987 crash exceeded the worst single-day falls of 1929

Evidence

On Monday October 19 the London market fell some 11 percent (Anonymous 1988a, p. 52), and in New York where the trading day is several hours later than London’s, because of the time zone difference the Dow fell 22.6 percent. It was its largest one-day fall ever, worse even than its worst individual days in the Great Crash: the 12.8 percent fall on October 28, 1929, and 11.7 percent fall on October 29, 1929 (Schwert 1990; Brady Commission 1988, p. 1). — Donald MacKenzie, An Engine, Not a Camera, 819