Amid a week of panic selling, the Dow plunged 12.8% on this Monday session as margin calls forced investors to dump shares en masse. Coming days after Black Thursday's initial shock, the collapse wiped out fortunes built during the speculative boom of the 1920s and signaled that the crisis was far from contained, deepening a downturn that would spiral into a decade-long global depression.
By late September 1929, the frenzied optimism of the Roaring Twenties had already begun cracking. Investors who had borrowed heavily to buy stocks on margin found themselves trapped when prices wobbled — brokers demanded more collateral, forcing further selling, which drove prices down further still in a vicious spiral.
On this Monday, the mechanism accelerated catastrophically. Ticker tape machines fell hours behind actual trading, leaving investors on the floor of the Exchange uncertain whether they were rich or ruined as prices flashed by. Traders later recalled a physical sickness in the air, executives pale and silent, messenger boys running between phones that never stopped ringing.
The crash did not single-handedly cause the Great Depression — structural weaknesses in banking, agriculture, and international trade mattered enormously — but it shattered confidence at a critical moment and triggered a wave of bank failures. Unemployment in the United States would climb past 20% within a few years, and the psychological scar of the crash shaped an entire generation's relationship with risk, debt, and the stock market for decades afterward.