Black Monday (October 19, 1987)

Black Monday on October 19, 1987, remains the largest one-day percentage drop in stock market history, with the Dow plummeting 22.6% and evaporating $500 billion in market value. Computerized program trading created a cascading sell-off that overwhelmed human traders, wiping out 30% more wealth in hours than #6's 1973 crisis did in weeks. This crash was faster than the average market correction, with a single day's loss exceeding the entire annual GDP of many nations. It stands as the benchmark for how technology can accelerate financial panic, outperforming #5 in speed of value destruction by 10 times.