Who is Warren Buffett?

Warren Buffett, born in 1930 in Omaha, Nebraska, is known for value investing and for building Berkshire Hathaway. His investment partnership began buying Berkshire, then a struggling New England textile maker, in 1962 and took control in 1965. Over six decades he turned it into a holding company that owns businesses outright and holds stakes in listed companies.

Greg Abel became Berkshire’s CEO on January 1, 2026, and in September 2026 Buffett became chairman emeritus while staying on the board. His long-time partner, Vice Chairman Charlie Munger, died in 2023. The best primary source for the method is Buffett’s annual letter to shareholders, which this guide paraphrases.

A warning before the rules: many people used similar ideas and did poorly, and nobody writes about them. Results like his are not typical, and the method fails often, mostly through wrong estimates and impatience. For a different famous approach, see Peter Lynch’s strategy.

Benjamin Graham’s influence: Mr. Market and the margin of safety

Buffett read Graham’s The Intelligent Investor, first published in 1949, early in 1950, at 19. He then studied under Graham at Columbia Business School, graduating in 1951, and worked at Graham’s investment firm from 1954 until it closed in 1956. Graham, often called the father of value investing, had written Security Analysis (1934) with David Dodd.

In his preface to a later edition, Buffett pointed readers to two chapters above all: chapter 8, on market fluctuations, and chapter 20, on the margin of safety.

Mr. Market
Graham’s imaginary partner who offers every day to buy your share or sell you his, at a price set by his mood: high when euphoric, low when gloomy. You may ignore him; his prices are there to serve you, not to guide you.
Margin of safety
Buying only when the price is well below your conservative estimate of value, so that a wrong estimate, bad luck or a few bad years do not ruin the investment. Graham called it the central concept of investment.
Intrinsic value
Berkshire defines it as the discounted value of the cash that can be taken out of a business during its remaining life. It is an estimate, not a precise figure, and two careful people will reach different numbers.

From cigar butts to wonderful companies at a fair price

Graham taught Buffett to buy mediocre companies at bargain prices. Buffett later called this the “cigar butt” approach: a discarded butt with one free puff left in it. It worked while he managed small sums, but it did not scale, and each bargain had to be replaced once its puff was gone.

In his 2014 letter, Buffett credits Charlie Munger with breaking the habit. Munger’s blueprint, as Buffett sums it up: stop buying fair businesses at wonderful prices and buy wonderful businesses at fair prices. Back in 1989 Buffett had written that Munger understood this early and that he himself was a slow learner.

Hypothetical: Company B trades at 6 times earnings, but its sales and profits shrink every year, so the bargain keeps getting cheaper. Company A trades at 20 times earnings, earns about 20% on its capital and reinvests at similar rates. The low multiple was not the cheaper purchase. See also growth investing.

This is also why Buffett rejects the growth-versus-value split: in his 1992 letter he wrote that growth is always part of the value calculation. The drawing below shows how the market labels the two kinds of stock; Buffett asks both what the future cash is worth and what you pay for it. See growth vs value stocks.

Turn your phone sideways to read the drawing. Tap to close.

Two hand-drawn panels: “growth”, with a steep sales line, a P/E 45 tag and bigger price swings, and “value”, with a gently rising line, a P/E 12 tag, a dividend tag and smaller swings.

Economic moats and the circle of competence

In his 2007 letter, Buffett wrote that a great business needs a lasting moat to protect its high returns on capital, since rivals will keep attacking any castle that earns them. His examples were being the low-cost producer and owning a powerful worldwide brand. The drawing at the top of this page adds two sources analysts often cite: network effects and switching costs.

A moat shows up in the numbers: high returns on capital held for many years while rivals try to copy the business. Buffett avoided industries prone to rapid change, where a moat must be rebuilt constantly. Hypothetical failure: Company D calls its brand a moat, but its return on capital has hovered near 7% for a decade, like its rivals. The brand is real; the moat is not.

The circle of competence is the second filter. In his 1996 letter Buffett wrote that you only need to evaluate companies inside your circle, and that knowing its boundaries matters far more than its size. A practical test before any purchase:

  • Explain in two sentences how the company makes money.
  • Name the moat and the number that proves it, such as return on capital over ten years.
  • Say what could break the moat in the next ten years.
  • If you cannot do all three, the stock is outside your circle: skip it, however cheap it looks.

Owner earnings and return on capital: the numbers behind the moat

In his 1986 letter Buffett defined owner earnings: reported earnings, plus depreciation, amortization and similar non-cash charges, minus the average yearly capital spending the business needs to keep its competitive position and unit volume (plus any extra working capital it needs). It is an estimate, since you must judge which spending is maintenance and which is growth.

Hypothetical, per share: Company A reports $3.60 of earnings, books $1.20 of depreciation and needs $0.80 of maintenance spending, so owner earnings are $3.60 + $1.20 − $0.80 = $4.00. Company B reports the same $3.60 but needs $2.50 of spending against $1.00 of depreciation: owner earnings of only $2.10. Same reported profit, very different businesses.

Return on capital measures how hard the money inside the business works. Buffett wrote in 1979 that the main test of management is a high return on equity capital, without undue debt or accounting tricks, rather than steady growth in earnings per share.

Return on equity (ROE)
Net income ÷ shareholders’ equity. Company A: $360 million ÷ $1.8 billion = 20%. Heavy debt shrinks equity and can inflate ROE, hence Buffett’s warning.
Return on invested capital (ROIC)
After-tax operating profit ÷ the debt plus equity used in the business. Company A: $380 million ÷ $2.0 billion = 19%. Analysts define it slightly differently, so compare companies with the same formula.

Warren Buffett investment strategy in practice: a hypothetical valuation

Berkshire says it never gives its own estimates of intrinsic value. What follows is one simple way to apply the idea to hypothetical Company A, with owner earnings of $4.00 per share.

Assume owner earnings grow 4% a year for a long time and you want a 10% yearly return. A simple growing-cash-flow formula gives next year’s owner earnings ÷ (required return − growth) = $4.16 ÷ 0.06 ≈ $69.33 per share. Now test the estimate: at 2% growth it is $4.08 ÷ 0.08 = $51.00; at 0% it is $4.00 ÷ 0.10 = $40.00.

Because the value is that uncertain, you demand a margin of safety, say 30% below the base case: buy only at about $48.50 or less. That price is still covered if growth is only 2%, though not if it is zero. The drawing below shows the idea: the dashed value line is an estimate, and you buy only in the shaded gap.

The failure case: a rival launches a cheaper product, and within two years Company A’s owner earnings fall to $2.50 and stop growing. The value is now about $2.50 ÷ 0.10 = $25, and the price drifts to $26. The “bargain” at $47 was a value trap: a margin of safety cannot cover a broken moat. The plan, step by step:

  1. Confirmation: the latest annual report still shows owner earnings near $4.00 and a return on capital near 20%. Results confirm the thesis; a falling price does not.
  2. Location: price versus value. At $72 there is no margin, so you wait. In a market-wide sell-off the price drops to $47, inside the gap.
  3. Exit rule: the method has no price stop; its protection is the margin of safety. If you borrow it, write a thesis-break rule first, for example: sell if owner earnings fall more than 25% or the return on capital stays below 12% for two years.
  4. Size: in a hypothetical $20,000 portfolio, cap one stock at 10%. At $47 that is 42 shares, or $1,974. In the failure case, 42 shares at $26 lose $882, about 4.4% of the portfolio; the whole $20,000 in that one stock would have lost about 45%. The position size calculator does the math.

Turn your phone sideways to read the drawing. Tap to close.

A dashed horizontal line labeled intrinsic value (estimate) and a wavy price line crossing above and below it; a shaded gap where price is far below the value line is labeled margin of safety, with a buy triangle, and a note reads value is an estimate.

Long holding periods and temperament

Buffett’s best-known line on time comes from his 1988 letter: “our favorite holding period is forever.” The condition matters: he wrote it about stakes in outstanding businesses run by outstanding managers, where holding for years lets high returns compound.

It is not a vow to hold everything. Buffett has written that keeping Berkshire’s textile business running for about two decades, until he closed it in 1985, was a costly mistake. Patience pays only on a good business.

Temperament is the harder part. In his preface to The Intelligent Investor, Buffett wrote that lifelong success needs neither genius-level intelligence nor inside information, but a sound way to decide and the discipline to keep emotions from wrecking it. The drawing below maps the moods Mr. Market cycles through.

Hypothetical: Company A’s owner earnings stay at $4.00 while its price swings from $72 near the euphoric top to $47 in the panic. The business did not change; the quote did. An investor with a written value estimate can use the panic; one without it tends to sell there. See trading psychology.

Turn your phone sideways to read the drawing. Tap to close.

A hand-drawn wave-shaped price curve with emotions written along it: optimism on the rise, euphoria at the top, anxiety at the first drop, then fear, panic at the bottom and hope in the recovery.

What does not transfer to day trading

Buffett’s edge works over years. On a 5-minute chart, price is Mr. Market’s mood minute by minute, and a company’s value does not change between 10:00 and 10:05.

A few habits do transfer: stay inside your circle of competence by trading one or two setups you know, wait patiently for a setup that meets your rules, size every position so one mistake is survivable, and ignore the crowd’s mood. See day trading for beginners. The rest does not carry over:

  • A moat says nothing about the next candle. A great company can fall 3% in a morning in a market-wide sell-off.
  • There is no intraday margin of safety. A day trader’s protection is a stop at a level and a fixed position size, as in risk management.
  • Buying more as price falls is a long-term investor’s choice, made on a value estimate. For a day trader, a broken level is a reason to exit, not a bargain.
  • Holding a business for years and holding a losing day trade overnight are different things. The second is hope, not patience.

Common misreadings of Buffett’s investing rules

Most mistakes made in Buffett’s name come from taking one rule without its conditions:

  • “Hold forever”, minus the condition: it applies to outstanding businesses with able managers, not to any stock you happen to own.
  • “A low P/E means value”: a cheap multiple on shrinking earnings is a value trap, the cigar butt with no puff left.
  • “A great company is a great buy at any price”: in the drawing below, hypothetical Company C doubles its earnings per share from $1.00 to $2.00 while its P/E falls from 60 to 25, so the price drops from $60 to $50. Great company, too high a price.
  • “Copy his portfolio”: institutional holdings reports (Form 13F) are filed up to 45 days after each quarter ends, and they show neither the price paid nor the reasons.
  • “Simple means easy”: the rules are short, but estimating value and sitting through a 40% drop are hard, and the method fails often.

Turn your phone sideways to read the drawing. Tap to close.

Two hand-drawn lines over the same years: EPS rising steadily in green while the share price falls in red, with a P/E 60 tag at the start, a P/E 25 tag at the end and a note reading great company, too high a price.