Share of wallet measures concentration: of everything a member spends in a category, how much goes to one brand. A member might spend a substantial amount with a retailer and still give most of their category spending to competitors. Share of wallet captures that context, showing not just what a member spends but how much of their available spending the brand has actually captured.
Consider two members who each spend the same amount with a grocer. One buys nearly all their groceries there; the other buys a fraction and splits the rest among three rivals. The second member represents far more headroom, since a program that persuades them to consolidate could multiply their spend without them spending a dollar more overall.
For an enterprise operator, share of wallet reframes the retention goal from holding a member to capturing more of what they already spend elsewhere. It identifies members with room to grow and justifies mechanics, such as tiers, bonuses, and ecosystem earning, designed to make consolidating spend worthwhile. Raising share of wallet grows revenue from the existing base rather than requiring new members.
