Concept · Strategy

Moats

High returns attract attackers. A moat is the reason they do not succeed, and the useful question is for how long.

A moat decides how long they last.

On February 8, 2011, a memo from Nokia's chief executive, Stephen Elop, reached the press. Elop told employees that the company was standing on a burning platform. Apple's share of phones priced above $300 had risen from 25% in 2008 to 61% in 2010. Android, which had appeared two years earlier, had that week overtaken Nokia in smartphone volume. In the United Kingdom, brand preference for Nokia had slipped to 20%, eight points lower than a year before, and it was also falling in what Elop called Nokia's traditional strongholds: Russia, Germany, Indonesia and the United Arab Emirates.

In one sentence

A moat is a structural reason a company's high returns are not competed away, and it is judged by how long that protection lasts.

Nokia still had a well-known brand and, in Elop's words, traditional strongholds. Neither stopped customers and developers from moving to a different kind of product. The episode shows the two questions a moat claim has to answer. What exactly keeps rivals from taking the profit? And for how long?

Warren Buffett made the metaphor a staple of investing. A moat is whatever makes that opportunity harder to take than it looks.

Morningstar turned the metaphor into a rating. Its analysts assign every company a wide, narrow or no moat, and they define the categories by time. A company whose advantages they expect to last more than 20 years has a wide moat. One that can fend off rivals for 10 years has a narrow moat. A firm with no advantage, or one that will quickly dissipate, has none. Morningstar names five sources: switching costs, network effects, intangible assets such as patents, licenses and brands, cost advantages, and efficient scale, which applies to markets that can support only one or a few competitors.

Two things follow. A moat is not the same as a good business, or a large one, or a profitable one. Profit is the evidence that something is working, and a moat is the reason it should keep working. And a moat is always defended against a particular attack. A brand protects against a rival that sells the same phone at a lower price. It does nothing against a rival that changes what a phone is.

Sources of moats

Morningstar groups economic moats into five sources. A company may combine more than one, but each claim still needs evidence of a specific mechanism and its durability.

Cost advantage

Serving customers at a lower cost than rivals can match

Switching costs

Leaving costs the customer more than staying

Network effect

Each new user makes the service worth more to the rest

Intangible assets

Patents, licenses and brands that rivals cannot copy

Efficient scale

A market with room for one or a few profitable suppliers

A continuum, not a switch

Moats sit on a spectrum of duration, and Morningstar's line between narrow and wide is 10 years versus more than 20. A moat can be strong against one attack and useless against another.

LowRivals can match it quicklyHighRivals cannot match it for decades

“Defensible advantages that last.”
— Execemy

Why it matters

A moat turns a good year into a good decade, and the decade is where the value is. Morningstar's 10-year and 20-year thresholds are statements about how long excess returns will last, and that length is what separates a business worth paying up for from one whose profits will be competed away. The useful question about a profitable company is therefore not how much it earns, but what would have to be true for a rival to earn the same, and how long that would take.

A moat is maintained by spending, not left alone. By 2007 it had 7.2%, and its annual advertising spend had grown from $31 million to $751 million.

Buffett's letter also sets limits on what can count. He rules out companies in industries prone to rapid and continuous change, and he rules out businesses that depend on a great manager. A moat that lives in one person, or in a technology that will be replaced, is a lead, not a barrier.

The practical test is a causal sentence: this asset protects this customer value from this rival's response, for this reason. If the sentence cannot name the customer, the rival and the mechanism, the claim is a hope. Then look for the observation that would falsify it. For a cost advantage, check unit costs as rivals grow. For a network, check whether users also use a competitor. For a brand, check what happens to demand when the price rises. A company that cannot say what would weaken its own moat has not identified it.

Real-world examples

The same concept shows up in different ways across industries.

VisaPayments network

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In fiscal 2025 Visa reported $40.0 billion of net revenue and $24.0 billion of operating income, about a 60% margin, after a $2.6 billion…

NVIDIAChips + CUDA software

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NVIDIA introduced CUDA in 2006, opening its graphics chips to general computing, and says more than 7.5 million developers now use CUDA and its…

Moody'sCredit ratings

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Moody's Investors Service reported a 63.6% adjusted operating margin in 2025 on a business registered with the SEC as a nationally recognized statistical rating…

When it breaks

Moats fail because the market moves to a different contest.

A leading position in a shrinking market is not a moat. Kodak filed for Chapter 11 protection on January 19, 2012.

Regulators can breach a moat that customers never wanted to cross. Visa's 10-K discloses that on September 24, 2024 the U.S. Department of Justice sued it under the Sherman Act, alleging that it monopolized debit network services through agreements with merchants and others. A court denied Visa's motion to dismiss in June 2025. The same filing notes a Federal Reserve cap on large-bank debit interchange of 21 cents plus 5 basis points and continuing interest in legislation that would require banks to offer a choice of card networks. Success at the scale of a network draws scrutiny in proportion to its returns.

The most dangerous rival can be the customer.

Key takeaways

01
What mechanism protects a customer outcome from which rival response, and for how long? What evidence would falsify the claim?
02
What investment keeps the advantage useful, and do the returns on that investment outlast its cost? GEICO shows how even a low-cost position required continued spending.
03
What is the strongest alternative attack: a substitute, a customer building its own option, or a change in the basis of competition? Test the moat against that attack.

Sources

Nokia CEO Stephen Elop rallies troops in brutally honest 'burning platform' memo · Engadget, 2011-02-08. Full text of the memo: Apple share of the $300+ segment, Android overtaking Nokia in smartphone volume, UK brand preference at 20%, ecosystem quotation
Berkshire Hathaway Inc. 2007 Chairman's Letter · Berkshire Hathaway, 2008-02. Business principles on the enduring moat, Roman Candles, Mayo Clinic; GEICO section: share 2.5% to 7.2%, advertising $31 million to $751 million; moats widened during the year test
The Morningstar Economic Moat Rating · Morningstar, 2020-02-26. Five sources of moat; wide moat above 20 years, narrow moat 10 years, none
Visa Inc. Form 10-K for fiscal year ended September 30, 2025 · U.S. Securities and Exchange Commission, 2025-11-06. Item 1 (credentials, merchant locations, volume); Item 7 (net revenue $40,000 million, operating income $23,994 million, litigation provision $2,562 million, debit interchange cap); Legal Proceedings (DOJ complaint of September 24, 2024)
NVIDIA Corporation Form 10-K for fiscal year ended January 25, 2026 · U.S. Securities and Exchange Commission, 2026-02-25. Item 1 (CUDA introduced in 2006, over 7.5 million developers); Item 7 (revenue $215.9 billion, up 65%); Item 1A competition risk factor
Moody's Corporation Form 10-K for fiscal year ended December 31, 2025 · U.S. Securities and Exchange Commission, 2026-02-18. Item 1 (MIS overview, NRSRO registration, competition); Item 7 (MIS Adjusted Operating Margin of 63.6%); Item 1A litigation and regulatory exposure
Eastman Kodak Company Form 10-K for fiscal year ended December 31, 2011 · U.S. Securities and Exchange Commission, 2012-02-29. Item 1 (FPEG segment description and digital substitution); Summary of Operating Data (net sales 2007 to 2011 by segment); Chapter 11 filing on January 19, 2012