Which stock market crash triggered the Great Depression?

Black Tuesday: The Day Wall Street Collapsed

On October 29, 1929 — a date that would go down in history as "Black Tuesday" — the New York Stock Exchange suffered one of the most catastrophic single-day collapses the financial world had ever seen. Share prices plummeted, panic spread like wildfire through trading floors, and billions of dollars in wealth simply evaporated. It was the trigger that sent the United States — and much of the world — spiraling into the Great Depression.

The Roaring Twenties Set the Stage

To understand the crash, you have to understand what came before it. The 1920s were a period of dizzying economic optimism in America. Stock prices had been climbing for years, and ordinary people — not just wealthy investors — were pouring their savings into the market. Many were buying on "margin," meaning they borrowed money to purchase shares, betting that prices would keep rising forever.

They were wrong.

By the autumn of 1929, cracks were already appearing. Industrial production was slowing, and stock valuations had ballooned far beyond what company earnings could justify. The market was, in modern terms, a bubble waiting to burst.

The Week Everything Fell Apart

The collapse didn't happen in a single dramatic moment — it unraveled over several days. On October 24, known as "Black Thursday," panic selling began. Bankers pooled resources to try to stabilize prices, but the effort was short-lived. By Monday, October 28, the market dropped nearly 13% in a single session. Then came Tuesday.

On Black Tuesday, over 16 million shares were traded — a record at the time — as investors desperately tried to sell. The ticker tape machines couldn't keep up. Crowds gathered outside the Exchange on Wall Street, anxious and confused. By the end of the day, the market had lost another 12%. Fortunes were wiped out in hours.

From Crash to Depression

The crash itself didn't immediately create the Great Depression — that took a combination of factors over the following years. Banks began to fail because they had loaned heavily against the now-worthless stocks. Consumer spending collapsed. Unemployment surged from around 3% in 1929 to nearly 25% by 1933. International trade seized up, partly worsened by protectionist policies like the Smoot-Hawley Tariff of 1930.

The Depression lasted throughout the 1930s, affecting countries around the globe and only truly ending with the economic mobilization of World War II.

A Lesson That Shaped Modern Finance

The 1929 crash fundamentally changed how governments regulate financial markets. The U.S. Securities and Exchange Commission (SEC) was created in 1934 specifically to prevent the kind of reckless speculation that had fueled the bubble. Deposit insurance through the FDIC was introduced to protect ordinary savers from bank failures.

Nearly a century later, the crash of 1929 remains the definitive warning about what happens when unchecked market euphoria runs headlong into economic reality.