The One Investing Rule Warren Buffett Swears By

Buffett opened his 2008 letter to Berkshire Hathaway Inc. (BRK.A, BRK.B) shareholders with a quote he credits to his teacher, Benjamin Graham: “Price is what you pay; value is what you get.”​

That’s the rule, but 2008 was a brutal year to talk about rules. Markets were collapsing, Lehman Brothers went under, and the S&P 500 ended down 37%. Berkshire’s book value dropped 9.6%, Buffett’s worst year since taking over in 1965, and investors everywhere got hammered.​​

Except that Buffett’s loss was nothing like everyone else’s. While the market lost more than a third of its value, Berkshire lost less than a tenth. And while others were panicking, Buffett spent that year deploying capital—$5 billion into Goldman Sachs (GS) and $3 billion into General Electric.

How To Put the Rule Into Practice

Most people think price and value mean the same thing. The markets will teach you otherwise, Buffett argues.

Price is whatever someone is willing to pay today. It bounces around based on fear, greed, headlines, and momentum—whatever mood controls the crowd. Value is what a business will actually produce in cash over time. Sometimes price and value match, but often they don’t. When they split apart far enough, Buffett buys.

Buffett’s 1966 letter to partners shows this principle put into action. That year, the Dow fell 15.6% while Buffett’s fund gained 20.4%. He called it the partnership’s best relative performance—a 36-point advantage. What happened? Buffett bought businesses trading below what they were worth, so when the market tanked, his investments held up because their value hadn’t changed. Only the prices had.​

Graham taught Buffett this at Columbia University in the early 1950s. Graham made a fortune buying stocks trading for less than their cash on hand. The market misprices things constantly, he taught, because most investors chase what’s moving instead of what’s cheap.​ Buffett spent decades proving Graham right.

How Buffett Applies This Principle During the Great Financial Crisis.

The financial crisis created exactly what Buffett looks for: quality businesses selling at ridiculous prices.

Take Goldman Sachs. In September 2008, with credit markets frozen and banks failing, Buffett bought $5 billion in preferred shares paying 10% annually, plus warrants to buy $5 billion more in common stock. Goldman bought back the preferred shares in 2011 for $5.64 billion. When Buffett exercised his warrants in 2013, his total profit was $3.7 billion.​

Buffett’s investment in General Electric followed the same pattern. Buffett invested $3 billion in preferred stock at 10% annual interest. GE redeemed those shares three years later, and Buffett pocketed a $1.5 billion profit.​

These weren’t gambles, since Buffett understood these companies would survive. Their temporary troubles didn’t reflect their long-term ability to generate cash. Their stock prices had simply fallen way below their value. So he bought. “Whether we’re talking about socks or stocks, I like buying quality merchandise when it is marked down,” Buffett wrote in 2008.

Why Following This Rule Is Hard

Calculating intrinsic value takes work. You have to understand a business—how it makes money, what advantages it has, and whether those advantages will last. You have to project future cash flows and discount them back to today. You have to build in room for mistakes.

Many investors don’t do that. They look at price charts, not balance sheets. They buy what’s going up and sell what’s going down. And that means they confuse momentum with value.

The rule also requires patience. Berkshire is holding a record $382 billion in cash in 2025. A critic might suggest that Buffett is being too cautious, as tech stocks have gained all year. But Buffett could argue he’s simply waiting for prices to drop below their value. That’s the rule at work. If the prices don’t end up cooperating, he doesn’t buy.