4) Moat trend
Economic moats aren't stagnant over time. Rather, competitive dynamics are constantly shifting as technology develops, regulations change, competitors exit or enter a market, companies gain scale, and so on. This is where our moat trend ratings come in.
If the underlying sources (or potential sources) of a company's competitive advantage are improving over time, the company has a positive moat trend.
If the underlying sources (or potential sources) of an economic moat are weakening or a company faces a substantial competitive threat that is growing, then it has a negative moat trend
For example, the switching costs and network effects that historically benefited Microsoft's Windows operating system are being steadily eroded by the growth in smartphones and tablets, where Google's Android and Apple's iOS dominate.