Here's an uncomfortable law of business: high profits attract competition, and competition destroys high profits. If your chai stall earns great margins, three more stalls open beside you within a year. Prices fall. Margins normalize. This gravitational pull acts on every business on Earth.
Which makes the real question: why do some companies earn fat profits for decades while gravity never catches them? The answer is a moat — some structural feature that keeps competitors from successfully attacking, the way a water-filled ditch protected a castle. The term comes from Warren Buffett, and it's arguably the single most useful lens in long-term investing.
Moats come in five real flavors. You interact with all five weekly:
Brand — customers pay more for trust itself. You could buy cheaper cola, chocolate, or sneakers, but a century of familiarity makes the known brand feel safer, and that feeling survives price increases (remember pricing power from Chapter 5? Brands are where it comes from).
Network effects — the product improves as more people use it. WhatsApp is useful because everyone's on it; a technically better rival with no users is useless. Each new user makes the moat deeper — competitors don't just need a better product, they need your entire crowd.
Switching costs — leaving is painful. Your bank isn't the best, but moving every EMI, salary credit, and auto-payment is misery, so you stay. Businesses feel this even harder: replacing company-wide software means retraining everyone. Customers stay not from love, but from friction — and friction pays dividends.
Cost advantage — structurally able to sell cheaper and still profit, usually through massive scale. A giant retailer buys stock so cheaply that its selling price sits near a small shop's cost price. Rivals can match the price only by losing money.
Regulatory/legal barriers — licenses, patents, and government permissions that competitors simply cannot get. Stock exchanges, credit-rating agencies, and patented medicines live here.
The investor's test isn't "does a moat exist today" — it's is the moat widening or narrowing? Technology drains old moats (a newspaper's distribution moat meant everything in 1995, nothing by 2015) and digs new ones. And the numbers verify the story: a real moat shows up as ROCE staying high for 10+ years (Chapter 6) — because that's precisely what a moat does: it protects returns from gravity.
Key Takeaway
Sustained high profits are abnormal — something must be actively protecting them. Name the moat, judge whether it's widening or narrowing, and confirm it in a decade of ROCE. No nameable moat usually means the fat profits are living on borrowed time.
Think About It
Pick any product you've bought for 5+ years without once comparing alternatives. Which of the five moats captured you?
Live Lab — Moat Verification
Open screener.in/company/ASIANPAINT/consolidated/ (Asian Paints — a classic Indian moat case built on brand + distribution). Check its 10-year ROCE. Then pick a steel or airline company and compare — industries with famously weak moats. Global version: check "Return on Capital (ROIC)" for Coca-Cola at stockanalysis.com/stocks/ko/statistics/. Write one sentence: which moat, and is it widening or narrowing?