Many investors focus on the current size of a company's competitive advantage. A better indicator of future success is the direction of that moat—is it growing or shrinking? Focusing on the trajectory helps avoid value traps like Nokia in 2007, which had a wide but deteriorating moat.

Games Workshop sustains its niche by creating intellectual property (narratives, characters) that fosters a dedicated, in-person community. This community financially supports the IP creation, understanding that without the company, their shared world fades. This cycle makes the business resilient to threats like 3D printing.

The biotech sector lacks mid-cap companies because successful small firms are typically acquired by large pharma before reaching that stage. This creates a barbell structure of many small R&D shops and a few commercial giants. The assets, not the companies, transition from small to large.

Gardner’s "Cola Test" is a simple heuristic to identify unique market leaders. Ask yourself if a company is the "Coca-Cola" of its industry. Then, try to name its "Pepsi." If you can't find a clear, direct competitor, you've likely found a business with a powerful, defensible moat.

A sustainable competitive advantage is often rooted in a company's culture. When core values are directly aligned with what gives a company its market edge (e.g., Costco's employee focus driving superior retail service), the moat becomes incredibly difficult for competitors to replicate.

Contrary to belief, downside protection in a growth portfolio is not about diversification. It's about owning companies whose competitive advantages are actively growing. During downturns, these companies can invest and take market share from financially constrained rivals, making them surprisingly resilient and defensive.

Top compounders intentionally target and dominate small, slow-growing niche markets. These markets are unattractive to large private equity firms, allowing the compounder to build a durable competitive advantage and pricing power with little interference from deep-pocketed rivals.

Sustainable scale isn't just about a better product; it's about defensibility. The three key moats are brand (a trusted reputation that makes you the default choice), network (leveraged relationships for partnerships and talent), and data (an information advantage that competitors can't easily replicate).