Morningstar's framework identifies five sources of economic moats. Network effects: each additional user makes the product more valuable for all users — Visa's payment network, Google's search, and LinkedIn's professional graph all gain value nonlinearly with scale. Switching costs: customers face significant cost, time, or risk when changing providers — Oracle database customers, Salesforce CRM users, and enterprise ERP systems stay for years because migration is painful and expensive. Cost advantages: structural cost leadership from scale, proprietary processes, or unique resource access — Costco's buying power and distribution efficiency, GEICO's low-cost direct distribution, and commodity producers with superior mining locations.

The remaining two sources: intangible assets — brand, patents, regulatory approvals, and proprietary data that competitors cannot easily replicate (Coca-Cola's brand commands a price premium globally; drug patents protect 20-year exclusivity windows); and efficient scale — operating in a market so small that a second entrant would destroy both incumbents' economics, typically in regulated infrastructure like local water utilities or regional airports. Many businesses have none of these; the best businesses have two or more that reinforce each other.

Moats express themselves quantitatively as sustained ROIC above cost of capital — typically above 15% — maintained over a full business cycle including at least one recession. Point-in-time ROIC is insufficient; the test is whether superior returns persist despite competitive pressure. Track ROIC across 7-10 years: if it remains consistently above 15% with low variance, the business likely has genuine structural protection. If ROIC spikes in good years and collapses in bad years, the business is cyclical, not moated.

Moats are not permanent. Kodak had a moat in photographic film; digital photography eliminated it in a decade. Nokia had a moat in mobile handsets; the smartphone disrupted it within five years. The highest risk of moat erosion today is in technology, where disruption cycles are shorter than in most industries. The relevant question is not 'does this company have a moat?' but 'how wide is it, how durable is it across likely disruption scenarios, and is it widening or narrowing?' The trajectory of ROIC over the past 5 years is often the best single proxy for moat direction.

The clearest real-world test of a competitive moat is pricing power: the ability to raise prices without losing meaningful volume. Businesses with genuine moats raised prices 5-15% in 2021-2022 without demand destruction — Apple's iPhone ecosystem, Hermes luxury goods, Berkshire's GEICO insurance, and Costco membership fees all absorbed price increases with minimal customer defection. Businesses without moats who attempted similar price increases saw customer churn and market share losses. Inflation periods are natural stress tests for pricing power, which is why wide-moat stocks often outperform in inflationary regimes.

Revenue retention rate is the SaaS-era quantification of moat strength. Net revenue retention above 110% means the existing customer base is growing its spend by more than 10% annually — through upsells, cross-sells, and expansion — even before new customer acquisition. Above 120% is exceptional and indicates deeply embedded, expanding product usage. Below 100% means existing customers are shrinking their spend, an acute warning sign regardless of gross new customer acquisition. In traditional businesses, comparable proxies are volume growth with price increases (pricing power) and long customer relationships with low churn.