The 1929 Crash and the Great Depression

In October 1929, the great boom of the Roaring Twenties ended in the most famous stock market crash in history, and the world slid into the deepest economic depression of the modern age.

What happened

Through the 1920s, American stocks had soared as ordinary people, for the first time, poured into the market. Then confidence broke. On Thursday, October 24, 1929 (Black Thursday), panic selling hit Wall Street. After a brief pause, the collapse resumed: on Monday, October 28, the Dow fell about 13%, and on Tuesday, October 29, 1929 (Black Tuesday), it fell roughly another 12% on record volume.

The damage did not stop there. The market kept grinding lower for nearly three years. By its bottom in July 1932, the Dow Jones had lost about 89% of its 1929 peak value. An investor who bought at the top would not break even for a quarter of a century.

Why it happened

The 1929 crash was the collapse of a classic speculative bubble, made far worse by how it was funded.

• Buying on margin. Investors could buy stock while putting up as little as 10% of the price, borrowing the rest from their broker. This let people control huge positions with little money, and it magnified every move. If that idea is new, borrowing to invest is exactly the danger described in risk management basics.
• Runaway speculation. Prices had detached from what companies actually earned. Shoeshine boys and taxi drivers famously traded stock tips, a sign the mania had reached everyone.
• The margin trap in reverse. When prices started falling, brokers issued 'margin calls', demanding investors put up more cash. Those who could not were sold out automatically, which pushed prices lower, triggering more margin calls. A downward spiral built into the system.

The aftermath

The crash alone did not cause the Great Depression, but it helped set it off and became its symbol. In the years that followed, thousands of banks failed, wiping out the savings of millions. U.S. unemployment climbed to around 25%, roughly one in four workers. Global trade collapsed and the misery lasted through the 1930s.

The disaster reshaped the rules of finance for generations. The U.S. government created the Securities and Exchange Commission (SEC) to police markets and require honest disclosure from companies. It created federal deposit insurance so that a bank failure would no longer erase ordinary people's savings, and it tightened the rules on how much investors could borrow to buy stock.

The lesson

1929 is the original cautionary tale, and its two lessons echo through every crash since. First, prices driven by pure speculation eventually snap back to reality. Second, and more importantly, borrowed money turns a market decline into a catastrophe. Margin does not just magnify gains on the way up; it forces selling on the way down, deepening the very fall that ruins the borrower.

The safeguards born from this crash, disclosure rules, deposit insurance, and margin limits, are a large part of why later crashes like Black Monday 1987 did not spiral into another depression.

For the difference between a booming and a falling market, see bull vs bear market.