Parlays, Correlation & Compounded Sportsbook Margin
Why multiplying leg prices can magnify pricing differences and why correlated legs require separate treatment.
A parlay combines multiple outcomes into one wager. If leg probabilities were independent and fairly priced, joint probability would be the product of the leg probabilities. Sportsbook prices include margin, and correlated legs cannot be modeled safely as independent.
Independent-leg math
If two independent events each have a true 50% probability, both occurring has a 25% probability.
Margin compounds
Multiplying already-margined offered prices can create a larger gap from a fair joint price.
Correlation
Same-game outcomes can be positively or negatively correlated. Multiplying standalone probabilities is wrong when dependence matters.
Rules and void legs
Operators can differ in how voided, pushed or resettled legs affect the parlay.
Use exact offered payout
Do not assume a generic “parlay multiplier.” Read the displayed combined price and settlement rules.