For most of betting history, combining selections from the same match was simply not allowed. The outcomes were correlated, the maths was awkward, and bookmakers refused the business. Then the technology caught up, and the product they once banned became the most profitable thing they sell. The same-game parlay, marketed in Britain as the Bet Builder, is now the centrepiece of every major sportsbook’s football and NFL offering.
From banned bet to flagship product
The breakthrough came from a London company called Sportcast, whose BetBuilder engine allowed bet365 to launch same-match combinations on football in the mid-2010s. In the United States, FanDuel brought the format to market after the Supreme Court’s May 2018 ruling in Murphy v NCAA opened the door to state-regulated sports betting, and the phrase same game parlay entered the American vocabulary during the 2020 NFL season. DraftKings, BetMGM and Caesars followed with their own versions. Within five years the product went from novelty to the default way a large share of recreational customers bet on big events; operators regularly report that a majority of Super Bowl bets are now parlays of some kind.
The correlation problem, solved in the house’s favour
Pricing a same-game parlay is genuinely difficult. A bet combining a striker to score, his team to win and over 2.5 goals is not three independent events. If the striker scores, the win and the goals total both become more likely. Simply multiplying the three prices together would overpay the customer, so operators run simulation models that play the match thousands of times and count how often the full combination lands. The customer sees a single combined price with no visible breakdown, and that opacity is where the margin lives.
Each leg of the combination carries its own share of overround, and the shares compound. Three legs at 5 per cent margin each produce a combined margin north of 14 per cent before any additional shading for correlation uncertainty, which operators price conservatively in their own favour. On a straight two-way market a sharp customer can compare prices across firms in seconds. On a bespoke five-leg builder there is no reference price anywhere, so competitive pressure barely operates. The general mechanics of margin are covered in the sports betting basics guide; the same-game parlay is that mechanism raised to a power.
What the numbers show
Regulatory filings make the economics unusually visible. Illinois is one of the few US states whose gaming board publishes parlay revenue separately, and its reports have consistently shown hold rates on parlay wagers running around three to four times those on single bets, with parlays holding in the high teens as a percentage of stakes while straight bets hold in the mid single digits. New York and New Jersey operator results tell a similar story through blended hold rates that climbed steadily as parlay share grew. In earnings calls, Flutter and DraftKings executives have both attributed rising structural margins largely to parlay mix, and analysts now track parlay penetration as a headline metric for the sector.
The UK picture is older but consistent. Multiples have always held better than singles, which is why football coupons and accumulators were promoted so heavily in the shop era, decades before an app existed. The Bet Builder simply moved that logic inside a single fixture and attached it to the most emotionally engaging bets available: named goalscorers, cards, corners and player shots.
Why regulators are starting to look
The product’s profitability has drawn attention. The Netherlands Gambling Authority and several academic groups have examined whether long-odds combination bets are disproportionately attractive to younger customers, and the UK Gambling Commission’s 2023 white paper process included discussion of how complex products are marketed. No major jurisdiction has restricted the format so far. The likelier constraint is mathematical literacy: a combined price of 25.00 on a builder whose fair odds are 40.00 is a poor exchange, but it is invisible without tools most customers do not have. For the operators, that gap between perceived and actual value is not a flaw in the product. It is the product, and it sits alongside the other pricing structures examined across the betting section.