Once you can name an economic moat, the temptation is to stop there: spot the one advantage, check the box, call the business protected. But a single advantage is a thinner defense than it looks. Charlie Munger, Buffett’s partner for fifty years, spent a career on the opposite idea. He called it the lollapalooza effect: when several forces push the same direction at once, the outcome isn’t the sum of them, it’s an extreme. He meant it about psychology, but it describes moats exactly. One source can be copied, regulated away, or out-engineered. Two that reinforce each other are hard to overcome. Three or more start to look permanent. So the real question isn’t “does this company have a moat?” It’s “how many, and do they hold each other up?”
Run the five-source check, then count
Pat Dorsey, who built Morningstar’s moat-rating research into the standard vocabulary analysts still use, sorted durable advantage into five sources: intangible assets (brand, patents, licenses), switching costs, network effects, cost advantage, and efficient scale. The intro article walks through each one. Here’s the move most investors skip: run the list as a checklist, and count how many actually apply. Not how loudly management claims a moat, but how many of the five you can defend with the numbers. A company that ticks one box is a candidate. A company that ticks three is a different kind of animal.
Call it a reinforcing stack: two or more moat sources that don’t just sit side by side but feed one another, so attacking one means running into the next. The count matters, but the reinforcement matters more. Two sources that protect different flanks beat two that guard the same gate.
When sources defend each other
Apple is the cleanest case, and it’s why Buffett, long allergic to technology, made it Berkshire’s largest stock position. The brand is an intangible asset: people pay a premium for the name, and Buffett likes to say a customer would give up their second car before their iPhone. But the brand alone wouldn’t hold if leaving were easy. So it sits on top of switching costs (your photos, messages, and purchases live inside the ecosystem) and a network of apps and accessories that gets more useful the more of it you own. Each source covers a flank the others leave open. The brand pulls you in, the switching costs keep you, the ecosystem makes staying feel like the obvious choice. Apple reports iPhone retention above 90%, which is what a reinforcing stack looks like in a single number.
Visa and Mastercard show the same logic in a less glamorous business. Strip them down and you find a two-sided network (billions of cards on one side, tens of millions of merchant locations on the other, each making the other more valuable), enormous scale that lets them process trillions in payments at operating margins above 50% with fewer than 40,000 employees between them, and a brand so embedded that “do you take Visa?” is a reflex. A rival can’t buy its way in, because the network took some sixty years to build, and you can’t out-spend the merchants and cardholders into existence. ASML is the industrial version: the only company on earth that makes the EUV machines advanced chips require, a monopoly resting on thousands of patents and more than two decades of accumulated process knowledge, plus the scale and switching costs of being designed into every leading-edge fab. Intangibles, scale, and switching costs, all pointing the same way.
What a single source leaves exposed
None of this means a single-source moat is worthless. eBay rode one network effect for years and rode it hard. But a single source is a single point of failure, and the history of broken moats is mostly the history of one advantage that turned out to be the only one. A patent expires. A regulator rewrites the rules on a licensed business overnight. A new standard arrives and a cost advantage built for the old way becomes a stranded asset. When a moat rests on one pillar, the company is one shift away from open water. When it rests on three that reinforce, the shift that breaks one still leaves the others holding the line, which buys management the rare thing in competition: time to adapt.
The discipline, then, is to resist the good story about the one great advantage and do the boring count instead. Walk Dorsey’s five sources, mark the ones the numbers support, and ask whether they defend different flanks or the same one. A wide-looking moat from a single source deserves more suspicion than a narrower-looking moat from three that interlock. Width is what you see today; reinforcement is what survives tomorrow.
Why a four-rank composite is harder to fool
This is the same instinct behind how Obermatt scores a stock, just turned on the numbers instead of the narrative. The 360° rankisn’t one metric dressed up as a verdict. It averages four peer-relative ranks (value, growth, safety, and sentiment) that deliberately pull in different directions, the way a reinforcing stack defends different flanks. A single metric is easy to game: a company can look cheap because it’s quietly dying, or look like a growth star while the balance sheet rots. Stack four lenses that don’t agree by nature, and a stock has to clear several at once to score well, which is far harder to fake than excelling at any one. A composite that demands strength on several fronts is, by construction, harder to fool than the single number that flatters a flawed business.
The principle is Munger’s, applied to competition: durability is rarely one thing, and the advantages that last are the ones that hold each other up. So the next time you read a company describe its moat, count. One source is a story. Three that defend each other is a fortress, and the difference between them is most of what separates a business that stays good from one that merely is good today.