Hold, or margin, is how much of the wagered value stays with the operator. It mirrors RTP: a 96% RTP corresponds to a 4% hold.
In sportsbook the distinction that matters most is between:
- Theoretical margin, the margin built into odds pricing, decided by trading. It is what the book intends to make.
- Realised margin, what actually remained after event results, cash out, promotions and arbitrage activity. It is what the book made.
The two diverge considerably over short windows, and that divergence is variance, not operational error. Demanding weekly explanations of realised margin tends to produce bad decisions; the right reading horizon is monthly or quarterly, with enough volume.
Factors that erode realised margin without showing in the theoretical one: mispriced cash out, loose limits in low-liquidity markets, and bet concentration on favourites.
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