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Benjamin Graham: how a 1929 wipeout created Mr. Market

Between 1929 and 1932, Benjamin Graham's fund lost about 70% of its value, by most accounts. He had been a Wall Street star. Instead of quitting, he spent the next two decades writing down how to never be that exposed again.

Story · 7-minute read · Updated 2026-10-21

Who they were

Benjamin Graham was born in London in 1894. His family moved to New York when he was a baby. His father died when he was young, and the family struggled for money.

He was a brilliant student. He finished second in his class at Columbia University in 1914. The university offered him jobs teaching English, math and philosophy. He turned them down and went to Wall Street instead.

By his early 30s he was running his own investment partnership, with a partner named Jerome Newman.

What happened

The 1920s

Graham did very well in the boom of the 1920s. His method was to look for companies selling for less than they were really worth, often less than the cash and assets they held.

But like almost everyone, he was exposed when the market turned.

The crash and after

The stock market crashed in October 1929. It kept falling, on and off, until mid-1932.

Graham's partnership lost about 70% between 1929 and 1932, by most accounts. Part of the damage came from borrowed money, which made the losses bigger.

He didn't walk away. He kept managing money, cut his own pay, and slowly rebuilt.

Writing it all down

In 1934, with his Columbia colleague David Dodd, he published Security Analysis. It was a thick, careful book on how to value a company.

In 1949 he published a shorter book for ordinary investors: The Intelligent Investor. It's still in print and widely read.

His later firm, Graham-Newman, made one famous buy. In 1948 it bought about half of the insurer GEICO. Sources give slightly different prices, around $712,000 to $736,000. The stake grew hugely over the next decades. Graham admitted that this one investment may have mattered more to his results than everything else combined.

The student

One of his Columbia students was a young man from Omaha named Warren Buffett. Buffett later worked for Graham-Newman from 1954 to 1956. Graham retired soon after, and died in France in 1976.

The moment everyone remembers

The idea people remember most is a character he invented in The Intelligent Investor: Mr. Market.

Imagine you own a business with a partner called Mr. Market. Every day he shouts out a price at which he'll buy your share or sell you his. Some days he's cheerful and the price is high. Some days he's gloomy and the price is low.

Graham's point: you don't have to do what Mr. Market says. His mood is not information about the business. You can ignore him, or use his mood when it offers a good deal.

A related line is often attributed to Graham, mostly by Buffett: in the short run the market is a voting machine, but in the long run it's a weighing machine. The exact wording is hard to find in Graham's own books, so treat it as a teaching line passed on by his student.

What it teaches

1. Build in a margin of safety

Graham's key idea was the margin of safety: only buy when the price is well below what you think something is worth, so even if you're somewhat wrong, you're still okay.

A trader's version is to plan for being wrong. Put a stop loss where the idea fails, and size the trade so that loss stays small. The position size calculator does the math.

2. Borrowed money makes losses bigger

Graham's worst years were made worse by borrowing. Leverage cuts both ways. Our guide to leverage and margin shows how fast a small move can become a big loss.

And deep losses are hard to climb out of. A 70% loss needs a gain of about 233% just to get back to even. Check it in the loss recovery calculator.

3. The market's mood isn't a plan

Mr. Market is a picture of emotion. Prices swing with fear and excitement. A written plan helps you decide while you're calm, before the swings. See trading psychology for beginners.

4. Write your rules down

After his worst losses, Graham turned his lessons into books. A beginner's version is a one-page trading plan. Each rule is a lesson you only have to learn once.

What it doesn't mean

It doesn't mean Graham's methods are trading methods. He was a long-term investor who studied company accounts. He didn't trade charts.

It doesn't mean cheap stocks always go up. Some stocks are cheap for good reasons, and Graham owned many that didn't work out. He spread his money across many of them on purpose.

And it doesn't mean one famous winner is a strategy. Graham himself said GEICO may have done more for him than all his careful rules. That's a lesson in luck, too. What carries over is the habit: plan for being wrong, and don't let the market's mood make your choices.

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