A moat is a reason profits survive
High profits attract competitors the way honey attracts wasps. A moat is whatever keeps the wasps out long enough for the profits to persist: a brand people pay extra for (pricing power you can see in gross margins), switching costs that make leaving painful, network effects where each user makes the product better, scale that lets you price below rivals' costs, or regulatory position.
The test is not the story; it is the numbers over time. Sustained high returns on capital across a decade, through at least one bad economy, is what a moat looks like in the accounts. One great year is weather; ten is climate.
What a fair value estimate actually is
Every fair value model is a disciplined guess: take what the business earns, assume how that grows, and translate the future into a present price. SteadyShares's screener uses an earnings-power model in the Graham tradition (earnings times a multiple that scales with growth), and says so on every page, because the assumptions matter more than the arithmetic.
What no model can know: whether the growth assumption survives reality, whether trailing earnings are a cyclical peak, what managers do with the cash, or what mood the market will be in. That is not a flaw to hide; it is the reason the next idea exists.
Margin of safety: the honest response to being wrong
If the estimate is uncertain (it is), then paying exactly fair value leaves no room for error. The margin of safety is the discount you demand between price and estimate; Graham wanted roughly a third. It converts "my model might be wrong" from a fear into a number.
The margin should widen when the estimate is shakier: thin data, cyclical earnings, heroic growth assumptions. SteadyShares pairs every estimate with a data-quality score for exactly this reason: a fair value standing on twelve real inputs and one standing on three are different claims, and your discount should know the difference.
Using both without fooling yourself
The moat tells you whether the earnings deserve a future; the fair value tells you what that future is worth today; the margin of safety pays for your mistakes. In that order. Skipping to the price target without the moat work is how value traps get bought, and every value trap was somebody's bargain.