Same-game parlay

A same-game parlay (SGP) combines selections from one match. Because outcomes inside one match depend on each other, a standard multiplication would misprice it, so the bookmaker runs a correlation model and returns a single price. Outside North America the same product is usually sold as a bet builder.

Correlation in numbers

Soccer, illustrative: home win 1.80, over 2.5 goals 1.90.

• If independent: 1.80 × 1.90 = 3.42, implied probability 29.2%.
• The book quotes 3.10, implied probability 32.3%.

The higher implied probability reflects positive correlation: when a strong home side wins, the match is more likely to have been high-scoring. Without seeing the book's fair probabilities, you cannot separate how much of that roughly 3-point gap is genuine correlation and how much is extra margin.

A €20 stake at 3.10 returns €62.

Margin

SGP prices are hard to check against a fair benchmark, and books generally earn a higher margin on them than on singles. Treat the quoted price with more suspicion than a main-market line.

Analysing an SGP

A quick check: price each leg's fair probability separately, estimate how strongly they move together, and compare the joint probability with 1 / offered odds. If you cannot do the second step with any confidence, you have no basis for judging the price. Also check the void rules: if one leg is voided, some books reprice the rest while others void the entire bet.