What Warren Buffett Actually Does

Value Investing — the Core Idea

Warren Buffett's approach is rooted in value investing, a philosophy he learned directly from his teacher and mentor, Benjamin Graham, at Columbia Business School in the early 1950s, and later refined substantially over the following seven decades. The central idea, stripped to its essence: every business has an intrinsic value — what it's genuinely worth, based on the cash it can be reasonably expected to generate for its owners over its remaining lifetime — and that intrinsic value is a different number from whatever the stock market happens to be pricing the business at on any given day.

Graham's famous metaphor for this gap was Mr Market — an imaginary business partner who shows up every single day offering to buy your shares or sell you more, at a price that swings wildly based on his mood: euphoric one week, panicked the next, rarely reflecting any sober reassessment of what the underlying business is actually worth. The value investor's job isn't to predict Mr Market's mood. It's to have an independent, reasoned view of what the business is worth, and to act — buying when Mr Market is pessimistic and offering a price well below that value, selling or simply declining to buy when he's euphoric and offering a price well above it — rather than being swept along by his mood from one day to the next.

Buffett's own refinement of Graham's approach, developed over decades and significantly shaped by his longtime business partner Charlie Munger, moved the strategy from Graham's original emphasis — buying statistically cheap, often mediocre businesses purely because the price was low relative to their assets — toward buying wonderful businesses at a fair price, rather than fair businesses at a wonderful price. The distinction matters enormously in practice: a cheap but mediocre business can stay cheap and mediocre indefinitely, or even deteriorate further, while a genuinely excellent business bought at a reasonable (not necessarily rock-bottom) price tends to keep compounding in your favour for decades, because its own quality does the work over time rather than requiring you to correctly predict when the market will "correct" an undervaluation.

The Circle of Competence

One of Buffett's most consistently repeated principles is staying within what he calls a circle of competence — investing only in businesses whose economics he genuinely understands well enough to form an independent, confident judgment about their long-term prospects. This is why Berkshire Hathaway largely avoided technology companies for decades, not because Buffett thought technology was unimportant, but because he didn't feel he could reliably judge which specific technology businesses would still hold a durable advantage in ten or twenty years, in an industry where competitive dynamics shift quickly and unpredictably.

This principle is frequently misunderstood as being about industry — "Buffett only invests in old-fashioned businesses" — when it's really about honest self-assessment of understanding. The size of anyone's circle of competence matters less than knowing, accurately, where its edges are, and refusing to invest meaningfully outside them regardless of how attractive an opportunity outside the circle might appear on the surface. Buffett has been explicit that most of his biggest investment mistakes came not from picking a bad business within a sector he understood, but from occasionally straying, under pressure or temptation, into situations he didn't actually understand as well as he believed he did at the time.

Economic Moats — What Buffett Is Actually Looking For

Buffett looks for businesses with durable economic moats — structural, lasting competitive advantages that protect a company's profits from being eroded by competitors over long periods, the way a literal moat protects a castle from being easily stormed. A business without a moat might be profitable today, but competitors can usually copy what it's doing, undercut its prices, or out-innovate it, eroding those profits over time. A business with a genuine moat can be copied in theory, but something structural makes doing so either impossible or uneconomical for a competitor to actually attempt.

What all five types share is durability — the advantage doesn't rely on the current management team being clever this year, or on a product remaining fashionable; it's built into the structure of the business and its industry, which is why it can persist, largely intact, for decades rather than being competed away within a few years the way an ordinary, moat-less advantage typically is.

Margin of Safety

The margin of safety is the gap between what you calculate a business is genuinely worth and the price you actually pay for it. If careful analysis suggests a company is worth £100 a share and you buy at £70, your margin of safety is 30%. This gap exists for a specific, humble reason: any estimate of intrinsic value is just that — an estimate, built on assumptions about the future that could turn out wrong in ways large or small. A sufficient margin of safety absorbs the inevitable errors in that estimate, and cushions against events — a recession, a new competitor, a regulatory change — that weren't foreseeable at the time of purchase.

Graham's original formulation treated the margin of safety as close to the entire strategy: buy only when the discount to calculated value is large enough to protect against being wrong. Buffett's evolution of the approach kept the margin of safety as a core principle, but paired it with a higher bar for business quality — a wonderful business bought with a smaller margin of safety can still be a better investment than a mediocre business bought extremely cheap, because the wonderful business's own ongoing growth continues widening the effective gap over time, while the mediocre business offers no such tailwind and relies purely on the market eventually recognising the original undervaluation.

"Forever" — Why Buffett Holds for Decades

Buffett has repeatedly said his favourite holding period is "forever," and Berkshire Hathaway's portfolio reflects this — stakes in companies like Coca-Cola and American Express have been held for multiple decades with no intention of selling based on short-term price movements. This isn't stubbornness or sentimentality; it follows directly from the logic of the moat concept. If a business has a genuinely durable competitive advantage, that advantage keeps compounding its value year after year without requiring the investor to do anything — no need to re-time an entry, no need to guess when to sell and when to buy back in. The business itself does the ongoing work.

This extremely long holding period also has a practical tax and cost advantage that Buffett has written about explicitly: every time a position is sold and a new one bought, transaction costs are paid and, in most jurisdictions, a taxable gain is realised and tax becomes due. A portfolio that's rarely traded defers that tax for decades, letting the full, untaxed amount continue compounding, rather than being periodically reduced by tax payments along the way. Buffett has described frequent trading, even when each individual decision is sound, as a quiet, cumulative drag on long-run returns through this mechanism alone — independent of whether the trading decisions themselves are good or bad.

Qualitative Factors Buffett Weighs Alongside the Numbers

Buffett's process isn't purely a spreadsheet exercise — he's written and spoken extensively about qualitative factors that matter as much as the numerical valuation, and arguably matter more for a holding period measured in decades rather than quarters.

• Management quality and honesty. Buffett has written that he looks for managers who think and act like owners, communicate honestly with shareholders (including about mistakes, not just successes), and allocate capital sensibly rather than growing the business for its own sake.
• Predictability of the business. A business whose future earnings are relatively easy to reason about — a consumer staple, an insurance operation with a long, stable history — is easier to value with confidence than a business in a fast-changing, unpredictable industry, even if the second business might theoretically offer higher growth.
• Pricing power. The ability to raise prices over time without losing meaningful customer volume is, in Buffett's own words, close to the single most important quality a business can have, because it protects profitability against inflation and competition simultaneously.
• Low capital intensity. Businesses that don't need to constantly reinvest large amounts of cash just to maintain their current position (as opposed to funding genuine growth) generate more free cash available to shareholders, rather than cash that's perpetually consumed just keeping the business where it already is.

Why This Approach Is Genuinely Hard to Copy

It's worth being honest about why Buffett's specific approach is extremely difficult for an individual investor to replicate successfully, beyond simply reading about it and deciding to try. Several distinct difficulties compound together.

Valuation skill. Estimating a business's intrinsic value accurately requires genuine accounting literacy, industry-specific knowledge, and the judgment to weigh qualitative factors (management, competitive dynamics, industry trends) alongside the numbers — a skill set that takes years of deliberate practice to develop and that even professional analysts frequently get wrong.

Psychological discipline under pressure. Buying when a business's price has fallen sharply and sentiment is uniformly negative requires acting against the overwhelming emotional and social pressure of the moment — everyone around you, including financial media, likely agrees the situation looks bad. Doing this well, repeatedly, over a career, is a genuinely rare temperament, and Buffett himself has said this discipline matters more to long-term results than raw intelligence.

Patience measured in years, not quarters. Holding through periods of underperformance, when a position lags the broader market for a year, two years, sometimes longer, before the thesis eventually plays out (or doesn't), requires a level of conviction and patience that's hard to sustain when every financial app shows you a live, constantly updating price.

Scale and access. Berkshire Hathaway's enormous capital base gives it access to deal structures, information, and negotiating leverage — buying entire companies outright, negotiating preferred terms during a crisis, as Buffett famously did with Goldman Sachs and General Electric during the 2008 financial crisis — that simply aren't available to an individual investor working with ordinary brokerage accounts and publicly available information.

What Buffett Himself Recommends for Ordinary Investors

This is the part of Buffett's public record that gets quoted far less often than his stock-picking successes, but it's arguably the most important thing he's said for the large majority of people reading about his strategy. Across multiple Berkshire Hathaway shareholder letters, interviews, and — notably — the instructions laid out in his own will for the trust that will manage money for his family after his death, Buffett's advice to the non-professional investor has been remarkably consistent: buy a low-cost S&P 500 index fund, keep adding to it regularly, and don't try to do anything cleverer.

Buffett has also publicly wagered on this view and won. In 2008, he bet $1 million (donated to charity by the winning side) that a simple S&P 500 index fund would outperform a hand-picked basket of actively managed hedge funds over the following ten years, after fees. By the bet's conclusion in 2017, the index fund had returned roughly 7.1% annualised; the hedge fund basket had managed roughly 2.2% annualised — a dramatic, public, decade-long demonstration of exactly the fee-and-skill dynamic covered in the index fund chapter of this course.

Why does the single most successful active stock-picker in modern history recommend passive investing for almost everyone else? Because he's drawn a clear, repeated distinction between what's achievable for someone dedicating their entire career, full-time, to studying businesses with institutional resources, versus what's realistic and sensible for someone with a job, a family, and limited time to research individual companies properly. His advice isn't a contradiction of his own approach — it's a direct, honest application of his own circle-of-competence principle to the audience he's addressing: most people's circle of competence doesn't include deep business valuation, and pretending otherwise is itself a risk.

How Berkshire Has Actually Performed — and Why Recent Years Look Different

Berkshire Hathaway's book value and share price have compounded at a remarkable rate since Buffett took control in 1965 — commonly cited at roughly 19–20% annualised over the full multi-decade period, compared to roughly 10% for the S&P 500 including dividends over the same stretch, though exact figures depend on the measurement period and method used and are worth checking against Berkshire's own published shareholder letters rather than a single rounded figure repeated secondhand.

In more recent years, Berkshire's outperformance relative to the S&P 500 has narrowed meaningfully, and Buffett himself has written about this directly and without spin. The core reason is scale: Berkshire now manages an enormous amount of capital, and finding an investment large enough to meaningfully move the performance of such a large company — while still offering an attractive discount to intrinsic value — is a dramatically harder problem than it was decades ago, when Berkshire was far smaller and a much larger universe of attractively priced opportunities was proportionate to its size. Buffett has explicitly told shareholders, repeatedly, not to expect the historical rate of outperformance to continue indefinitely, precisely because of this scale constraint.

The Mistakes Buffett Openly Admits To

Part of what makes Buffett's shareholder letters genuinely useful reading, beyond the investment principles, is his consistent willingness to publicly document his own mistakes in detail, rather than only highlighting successes. A few of the most frequently cited:

• Berkshire Hathaway itself. Buffett has called his original purchase of the failing textile business that became Berkshire's namesake one of his biggest mistakes — he bought it partly out of spite toward the previous owner rather than sound business reasoning, and the core textile operation ultimately failed, though the corporate shell survived to become the investment vehicle it is today.
• Staying too long in a fading business. Buffett has acknowledged keeping capital tied up in Berkshire's original textile operations for years longer than the economics justified, a mistake he's attributed partly to sentimental attachment overriding clear-eyed analysis.
• Missing technology opportunities for too long. Buffett has openly regretted not investing in some technology businesses earlier, including publicly stating he was slow to appreciate the durability of Amazon's and Google's advantages, a direct consequence of his circle-of-competence principle keeping him out of a sector he didn't feel equipped to evaluate confidently — a trade-off he's acknowledged cost real, if hard-to-quantify, returns.

The willingness to document these in writing, year after year, in a widely read public document, is itself an instructive part of the overall approach: treating investment mistakes as information to learn from and disclose honestly, rather than something to obscure, minimise, or blame on external circumstances.

Charlie Munger's Influence on the Approach

It's difficult to discuss how Buffett's strategy evolved without discussing Charlie Munger, his business partner and vice-chairman of Berkshire Hathaway for over four decades until Munger's death in 2023. Buffett himself has repeatedly credited Munger with pushing him away from Graham's original, narrower style — buying statistically cheap, often low-quality businesses purely because the price looked low relative to tangible assets — and toward the "wonderful business at a fair price" framework that defined most of Berkshire's later, larger successes.

Munger brought a distinct mental toolkit to the partnership, most famously his advocacy of multidisciplinary thinking — the idea that good judgment in business and investing comes from combining mental models borrowed from psychology, economics, mathematics, physics, and biology, rather than relying on a single analytical framework in isolation. His well-known emphasis on avoiding "stupid mistakes" rather than chasing brilliant ones ("it is remarkable how much long-term advantage people like us have gotten by trying to be consistently not stupid, instead of trying to be very intelligent") is, in practice, a psychological complement to the margin of safety concept: both are defensive, error-reducing mechanisms rather than aggressive, prediction-based ones.

The purchase of See's Candies in 1972 is often cited as the clearest early turning point in this shift. By Graham's stricter, asset-based criteria, See's wasn't obviously cheap. But Munger argued, successfully, that the brand's pricing power and customer loyalty — a genuine moat — justified paying a higher price than Graham's framework alone would have supported, and See's went on to generate returns for Berkshire many multiples of the original purchase price over the following decades. Buffett has repeatedly pointed to this single decision as the moment his own approach meaningfully changed.

The Difference Between 10% and 20% Annual Returns, Made Concrete

Buffett's long-run compounding rate, commonly cited at roughly 19–20% annualised over Berkshire's history versus roughly 10% for the S&P 500 including dividends, sounds like a modest difference when stated as two percentage figures next to each other. Compounded over decades, the gap becomes almost impossible to intuit without working through the actual numbers.

This table exists mainly to make one point vivid: doubling an annual return doesn't double the long-run outcome — compounded over forty years, it multiplies it by more than thirty times. This is exactly why Buffett's sustained, multi-decade outperformance has produced a fortune that looks almost incomprehensible relative to a "merely" market-matching return over the same period, and it's also why even a seemingly modest, sustainable edge, maintained consistently over a very long time, dwarfs a larger-looking edge that only lasts a few years. It's a useful table to hold onto any time an investment opportunity promises "just a few extra percent a year" — over a long enough horizon, that phrase is doing far more work than it sounds like.

Applying the Principles to UK Investing

The core principles — intrinsic value, economic moats, margin of safety, circle of competence — are not specific to US markets and apply equally to the FTSE 100, FTSE 250, or any other market. The UK market contains businesses with genuine, durable moats: strong consumer brands, companies with regulatory protection, and firms with high switching costs for their customers, spread across sectors from consumer goods to insurance to infrastructure.

The challenge of actually applying the approach is identical to the challenge anywhere else: accurately estimating intrinsic value, honestly assessing whether a moat is genuinely durable or merely currently convenient, and maintaining the discipline to hold through periods when the market disagrees with your assessment. None of that becomes easier simply because the shares are UK-listed rather than US-listed. For UK investors drawn to try value investing on individual shares, the same honest self-assessment applies as for any investor anywhere: this is a skill that takes years to develop credibly, and Buffett's own, repeated recommendation — a low-cost, broadly diversified index fund (a global one, or a UK-inclusive global tracker, rather than necessarily the S&P 500 specifically for a UK investor) — remains the more realistic approach for the large majority of people, regardless of which country's stock exchange they're looking at.

What to Actually Take From This, Practically

Pulling the strategy and the self-aware caveats together into something usable: Buffett's framework — understand a business, find a durable advantage, buy with a margin of safety, hold for the long term — is genuinely sound and worth understanding even if you never apply it directly to individual stock-picking. Understanding why a moat matters, why fees compound against you, and why patience beats activity will make you a better investor in any strategy, passive or active.

But the honest, repeated message from Buffett himself is that most people, including many who enjoy reading about his approach, are better served following his stated advice rather than his personal method: a low-cost, broadly diversified index fund, added to regularly, held for decades, left alone. That isn't a lesser or lazier conclusion to this chapter — it's the conclusion the single most successful investor of the last century has reached, in writing, for the audience most readers of this chapter actually belong to.