How to Spot a Widening Moat

A widening moat is a competitive advantage that is getting stronger, not just holding steady. You spot it when returns on capital rise or stay high as the business grows, market share climbs, and the source of the advantage deepens with scale, use or network size. A widening moat is the most valuable kind to own.

Most moat analysis asks whether an advantage exists. The more profitable question is which way it is moving. A moat that is quietly getting stronger each year is worth far more than one that is slowly leaking, and learning to tell the difference is one of the highest-value skills in investing.

Where this fits: this builds on Criterion 2, “Does it have a durable moat?”, by asking about the moat’s direction over time. Start with our moat hub and our guide to return on invested capital before applying it in the Five Criteria framework.

Wide Versus Widening

A wide moat describes how large an advantage is today. A widening moat describes which direction it is heading. The two are different, and the distinction is easy to miss.

Morningstar, whose moat ratings popularised the language, distinguishes a wide moat, expected to protect excess returns for at least twenty years, from a narrow moat, expected to last at least ten. But a rating is a snapshot. A business with a wide moat today can be in slow decline, while a business with a narrower moat can be deepening it fast.

For a long-term investor, direction often matters more than the current level. A widening moat means the odds of the business still earning high returns in fifteen years are improving, not fading. That is what you most want to own.

Why direction beats level

Charlie Munger’s point that your long-run return tends to track the return the business earns on its capital has a time dimension. The longer high returns last, the more they compound. A widening moat extends that period, and a narrowing one shortens it, so the same current return can be worth very different amounts depending on where it is headed.

The Signs of a Widening Moat

A widening moat leaves evidence in both the numbers and the business. Look for several signs together, not one in isolation.

Sign	What it looks like
Returns hold as capital grows	ROIC stays high or rises while invested capital increases
Market share climbs	The leader pulls further ahead of rivals year after year
Pricing power strengthens	Gross margin stable or rising through cost inflation
Retention improves	Churn falls; customers stay longer and spend more
Reinvestment at high rates	The company deploys large sums and still earns well on them

The single most important sign is the first one. If a company can grow its invested capital substantially while keeping ROIC high, it is both finding places to reinvest and protecting the returns on that reinvestment. That combination is rare and extremely valuable.

Which Moats Tend to Widen

Not all moat sources widen equally. Some get stronger with scale and use; others are fixed or decay.

Network effects

A network effect can widen almost mechanically. Each new user adds value for every existing user, so as the network grows, the gap over a smaller rival grows too. Hamilton Helmer, in 7 Powers, makes exactly this point: the leader’s advantage can widen as it grows, because each new user adds more to the larger network than to the smaller one. This is the classic widening moat.

Switching costs

A switching-cost moat deepens with use. Every year a customer adds more data, more integrations and more trained staff, the cost of leaving rises. A product that becomes more embedded in a customer’s operations each year is widening its moat even if nothing else changes.

Shared scale economies

A scale advantage can widen when savings are passed back to customers as lower prices, driving more volume and lowering costs further. Nick Sleep described this self-reinforcing loop as “scale economies shared”, explored in our guide to the Nomad partnership. It is one of the most durable widening moats because it compounds on itself.

Brands and patents usually do not widen

A brand or patent tends to hold steady or erode rather than widen. A patent weakens as it nears expiry. A brand must be constantly reinvested in just to stay where it is. These can be strong, durable moats, but they are less often the source of a widening one.

How to Test Whether a Moat Is Widening

Direction is a claim about change over time, so the test is always a trend, never a single year.

Test 1: ROIC against growing capital

Lay out ROIC and invested capital side by side for ten years. The ideal pattern is invested capital rising substantially while ROIC stays high or climbs. That shows the company reinvesting heavily without diluting its returns.

Test 2: market share over time

Track the company’s share of its market against its main rivals. A leader whose share keeps climbing is widening its position. A leader whose share is slipping, even while revenue grows with the market, may have a moat that is narrowing.

Test 3: the margin and retention trend

A gross margin that strengthens through a decade of cost inflation, and customer retention that improves rather than erodes, both point to a deepening advantage. Pair these with the pricing power tests.

Test 4: the cycle test

The hardest and most important test is whether the moat widened through a full cycle, including a downturn. A tailwind from a strong economy can look like a widening moat until the tide goes out. If the advantage deepened even in a bad year, it is real.

Worked Example: Two Platforms Over a Decade

Imagine two hypothetical platform businesses, Company A and Company B, over ten years. Both started with a clear moat. The figures below are illustrative, not real.

Measure	Company A, Year 1	Company A, Year 10	Company B, Year 1	Company B, Year 10
Invested capital	$200m	$900m	$200m	$850m
ROIC	22%	28%	22%	14%
Market share	30%	45%	30%	26%
Gross margin	70%	76%	70%	62%

Company A deployed far more capital over the decade and earned a higher return on it by the end, while gaining share and improving its margin. Its moat widened: it grew larger and stronger at the same time. This is the compounding engine investors prize most.

Company B grew its capital base too, but its returns, share and margin all drifted down. It reinvested into a weakening position, so the growth added less value each year. Its moat narrowed even as the business got bigger. Company A is the far more attractive long-term holding, and the difference is entirely in the direction of the moat.

Where Investors Go Wrong

• Confusing a tailwind with a widening moat. A rising market lifts everyone. Check whether the company is gaining share, not just growing with its industry.
• Trusting one strong year. Direction needs a decade, or at least a full cycle. A single good year proves nothing about the trend.
• Ignoring reinvestment runway. A moat that is widening but has nowhere left to deploy capital compounds more slowly than one with a long runway of high-return reinvestment ahead.
• Paying any price for the story. Even a widening moat has a value above which it is not worth paying. Price remains Criterion 5, and overpaying is still the largest risk to your wallet.

How This Fits the Five Criteria

Criterion 2 asks whether a durable moat exists. Assessing whether it is widening or narrowing is how you judge its durability honestly. A widening moat strengthens the case for the business and lengthens the period of high returns you can reasonably expect; a narrowing one shortens it and demands a larger margin of safety on price.

When you confirm a moat, do not stop at “it exists”. Lay out ten years of ROIC, capital, share and margin, and decide which way the advantage is moving. A business whose moat is widening, bought at a sensible price, is close to the ideal the Five Criteria are built to find.

Frequently Asked Questions

What is the difference between a wide moat and a widening moat?

A wide moat is large today; a widening moat is getting larger over time. A business can have a wide moat that is slowly shrinking, or a narrower moat that is deepening fast. The direction matters as much as the current width, and a widening moat is the more valuable trait to find.

Which moat sources are most likely to widen?

Network effects can widen as each new user adds value for all the others. Switching costs deepen as customers add more data and integrations. Shared scale economies widen as growth lowers costs further. Brands and patents tend to hold or erode rather than widen, so they are less often sources of a widening moat.

How do I see a widening moat in the numbers?

Look for ROIC that stays high or rises as invested capital grows, gross margins that are stable or improving, market share that climbs year after year, and customer retention that strengthens. A company reinvesting heavily while returns hold up is the signature of a moat that is widening.

Why is a widening moat so valuable?

Because it lets a company put large amounts of new capital to work at high returns for a long time. That is the ideal compounding engine: growth that creates rather than destroys value, sustained because the advantage protecting it is getting stronger, not weaker.

Can a moat stop widening?

Yes. A network can saturate, switching costs can be lowered by new standards, and shared-scale advantages can reach their limit. A widening moat should be re-checked every year, because the trait that makes it valuable is exactly the one that can change.

Your Next Step

Take a company you consider high quality and lay out ten years of ROIC, invested capital, market share and gross margin. Decide whether the moat is widening, holding or narrowing, and name the source driving the trend. Revisit the moat hub, see how durability fits the whole process in the Five Criteria framework, and record your findings with the Five Criteria Checklist.

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About the author: Cameron Hayes is a senior investor relations and finance professional who has worked in IR at Nasdaq Copenhagen-listed companies including Nilfisk and Maersk Drilling. He holds an MSc from Copenhagen Business School and a BCom from the University of Ottawa, and founded Gingernomics to teach individual investors the Five Criteria framework. More about Gingernomics.

The content on Gingernomics is for educational and informational purposes only and does not constitute financial advice. Always do your own research and consult a licensed financial advisor before making any investment decisions. Past performance is not indicative of future results.