A parlay, accumulator (or acca), combo bet, or multi is a single bet that links together two or more individual wagers, usually seen in

sports betting Sports betting is the activity of predicting sports results and placing a wager on the outcome. Sports bettors place their wagers either legally, through a sportsbook or bookmaker (colloquially known as "bookies"), or illegally through priva ...

. Winning the parlay is dependent on all of those wagers winning together. If any of the bets in the parlay lose, the entire parlay loses. If any of the plays in the parlay ties, or "pushes", the parlay reverts to a lower number of wagers with the payout odds reducing accordingly. Parlay bets are high-risk, high-reward; linking the possibilities drastically reduces the chance of the bet paying off overall. The benefit of the parlay is that there are much higher pay-offs, although as usual, casinos and bookkeepers offering parlays often exploit the poor calculation of gamblers by not increasing the pay-out as much as the odds truly demand, with the effect of the

house edge A casino game is one in which players gamble cash or chips on various possible random outcomes or combinations of outcomes, often in a casino environment. Such games are also available in online casinos, where permitted by law. Casino games can ...

increasing in parlays. Although a variety of bets can be used to build a parlay bet, correlated parlays are usually not allowed by traditional bookmakers. Correlated parlays are two or more bets from the same game that rely on a closely related outcome: for example, betting that a football (soccer) team might both score more than three goals in a match, and also win the match. These are not

independent events Independence is a fundamental notion in probability theory, as in statistics and the theory of stochastic processes. Two events are independent, statistically independent, or stochastically independent if, informally speaking, the occurrence of ...

, as a team that scores more than three goals is also very likely to win the match. A naive application of odds that treated these events as uncorrelated would not accurately reflect the probability of the linked bet. However, with the rise of sports betting through

mobile gambling Mobile gambling refers to playing games of chance or skill for money by using a remote device such as a tablet computer, smartphone or a mobile phone with a wireless internet connection. Over a hundred mobile casinos were operating as of December ...

apps in the late 2010s–2020s, this traditional hesitance has weakened. These newer apps often allow "microbets" on

proposition A proposition is a statement that can be either true or false. It is a central concept in the philosophy of language, semantics, logic, and related fields. Propositions are the object s denoted by declarative sentences; for example, "The sky ...

s such as if the current possession will end in a score, and further allow these props to be bundled into parlays. The system then attempts to compensate on how correlated these props are. While these systems usually prefer to lean heavily in the house's favor, the increased volatility from these bundles has resulted in some notable cases where bettors have found favorable odds. This isn't always a windfall for the bettors, though, as these newer-style sportsbooks have sometimes simply refused to pay out in those cases if the parlay comes through.

History

Parlays were introduced into New York-area racetrack gambling in 1988, but a 1989 newspaper article indicated that they still weren't very popular, perhaps due to the large surcharges and fees charged by off-track betting (OTB) parlors.

Odds and payout

Parlay bets are paid out at odds higher than the typical single game bet, but still below the "true" odds. For instance, a common two-team NFL parlay based entirely on the spread generally has a payout of 2.64:1. In reality, however, if one assumes that each single game bet is 50/50, the true payout should instead be 3:1.

Examples

Typical payouts for up to 10 team parlay bet

The following is an example of a traditional Las Vegas Parlay Card, which shows the typical payouts for an up to 10 team parlay bet based on −110 prices (amount won is assuming $100 is bet) and if every match is 50/50:

Profitability of parlays in sports betting

The best way to analyze if a parlay is profitable in the long term is by calculating the

expected value In probability theory, the expected value (also called expectation, expectancy, expectation operator, mathematical expectation, mean, expectation value, or first Moment (mathematics), moment) is a generalization of the weighted average. Informa ...

. The formula for expected value is:

= x_p_ + x_p_ + x_p_ \dots x_p_

. Since the

probability Probability is a branch of mathematics and statistics concerning events and numerical descriptions of how likely they are to occur. The probability of an event is a number between 0 and 1; the larger the probability, the more likely an e ...

of all possible events will add up to 1 this can also be looked at as the weighted average of the event. The table below represents odds. Column 1 = number of individual bets in the parlay Column 2 = correct odds of winning with 50% chance of winning each individual bet Column 3 = odds payout of parlay at the sportsbook Column 4 = correct odds of winning parlay with 55% chance of winning each individual bet The table illustrates that if a 55% chance of winning each individual bet were achievable, parlays would be profitable in the long term against the usual house edge. Compare the expected value received on an individual bet at a typical price of −110 with a 55% chance of winning: ((100/110+1)*.55)−1 = .05 (exactly 5 cents won for every dollar bet on average), multiplied by 11 = .55, to the expected return on the 11 game parlay ((1234/717.8)−1) = .719 (72 cents won for every dollar bet on average).

References