From September 3, 1929, to July 8, 1932, the Dow Jones Industrial Average fell by -89.2%, though certainly not in one fell-swoop. In fact, the decline known as the "1929 Crash" took the Dow down by an initial -47.9%, setting a trough on November 13, 1929. That initial decline was followed by a 48.0% recovery that peaked on April 17, 1930, leaving the Dow still -22.9% below its bull market high, because that's how compounding works. By the 1932-low, the Dow had plunged -86.0% below its April 1930 peak, and -79.3% below even the "bottom" it set in November 1929 after losing nearly half of its value.