What it means
Through the 1920s, share prices rose strongly as the economy grew and more households began to invest. Many investors bought on margin, which means they paid only a small part of the price and borrowed the rest from their broker.
This made gains larger on the way up, but it made losses far more dangerous on the way down. In late October 1929, prices began to fall sharply, and days such as Black Thursday and Black Tuesday became famous for panic selling.
When prices fell, brokers made margin calls, demanding more money from investors who could not pay, and forced sales pushed prices lower still. This is a feedback loop in which falling prices cause selling that causes further falls.
The crash itself did not cause the Great Depression on its own, but it hit confidence, wealth and bank balance sheets just as the economy was weakening. Bank failures, a shrinking money supply and falling spending then deepened the downturn.
Economists still debate the relative weight of each cause. Regulation changed as a result.
The United States created the Securities and Exchange Commission in the 1930s, introduced requirements for companies to disclose financial information and separated commercial and investment banking for a time. Many of the disclosure habits that finance staff follow today, including audited accounts, trace back to this period.
The market took about 25 years to return to its 1929 peak in nominal terms. For business readers, the main lessons are the danger of high debt, the speed at which a loss of confidence spreads and the value of reliable information.
In practice
Real-world examples.
Example
A teacher of business history uses the crash to show how margin lending works. An investor who put down $1,000 and borrowed $9,000 to buy $10,000 of shares would be wiped out by a 10% fall. The example makes the risk of borrowing to invest very clear.
Example
A bank risk manager reviews her lender's exposure to customers who have borrowed against their share portfolios. She sets rules requiring more collateral when prices fall, which draws directly on the lessons of the crash. The policy reduces the chance of forced selling.
Example
A company's finance director writing a board paper on capital structure cites the period as a reminder that heavily indebted businesses fail quickly in a downturn. He recommends keeping debt levels moderate and cash reserves adequate. The board adopts a limit on borrowing relative to earnings.
Formula
Calculation
Percentage decline = (peak level - trough level) / peak level
Using rounded figures for the Dow Jones Industrial Average, the index stood near 381 at its 1929 peak and near 41 at its 1932 low. Decline = (381 - 41) / 381 = 340 / 381 = 89.2%. To get back to the peak from the low, the index needed to rise by (381 - 41) / 41 = 340 / 41 = 829%. This shows why recovery from a deep fall takes so long.Case study
Seen in the real world.
Lanternfield Mills is an illustrative, fictional manufacturer used here to show how a business might have been hit by a crash of this kind. In the late 1920s it borrowed heavily to expand, and its owners also used borrowed money to buy shares in other companies.
When prices collapsed, the company's lenders demanded repayment, its customers cut orders and the value of its share holdings fell by most of the amount invested. The illustrative business was forced to sell its newest plant at a steep loss.
The lesson drawn by the fictional owners' successors was to separate the company's operating finances from speculation and to hold a reserve of cash. This pattern of caution is the same one that real businesses took from the period.
Watch out
Common mistakes.
- Believing the crash alone caused the Great Depression, when weak banks, falling spending and policy errors also played major roles.
- Assuming the market collapsed in a single day, when prices fell over several days in October 1929 and then kept falling until 1932.
- Thinking the crash can only be explained by greed, when the lack of company disclosure and heavy use of margin debt made the system fragile.
Questions
People also ask.
What was the main cause of the 1929 crash?
There was no single cause, but heavy speculation using borrowed money, high valuations and a weakening economy combined to make prices fall sharply once confidence broke.
How long did the market take to recover?
In nominal terms, the main US index did not regain its 1929 peak until the mid-1950s, roughly 25 years later.
What changed in regulation afterwards?
The United States introduced securities laws requiring honest disclosure, created the Securities and Exchange Commission and tightened rules on margin lending and banking.
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