An arbitrage (or arb for short) also known as 'surebets', 'surewins' and 'miraclebets' are bet types whereby a bettor wagers on a series of events that guarantees a profit no matter the outcome of an event, or at worst, guarantees that no money can be lost but a profit can still be made depending on the result of that event.

Arbitrage bets work by taking advantage of discrepancies in prices of the same event between different Sportsbooks in a way that can ensure the bettor can't lose money no matter the outcome of the event.

Arbitrage opportunities can pop up in betting markets for a variety of reasons, most commonly being a disagreement in Sportsbook opinions on a certain event.

For example, say an NBA game was being played between the Houston Rockets and the Cleveland Cavaliers. 'Sportsbook A' may open up their market at:

Houston Rockets $1.50 (e.g -200)

Cleveland Cavaliers $2.50 (e.g +150)

And 'Sportsbook B' may open up their market at:

Houston Rockets $1.80 (e.g -125)

Cleveland Cavaliers $2.20 (e.g +120)

You can see here that there is a discrepancy in the odds, or a disagreement between the sportsbooks over the winning chances of each team. In this scenario, the bettor could place $55.55 on the Houston Rockets with Sportsbook B, to receive a payout of $100 if Houston wins and the bettor can place $40.00 on the Cleveland Cavaliers with Sportsbook A, to also receive a payout of $100 if Cleveland wins.

In this scenario, no matter who wins the game, the bettor has outlaid $95.55, but will receive back $100 regardless of the outcome. This is a sports betting arbitrage, an opportunity to guarantee yourself a profit no matter the result (e.g + to your bankroll!)