Risk and fraud

Arbitrage betting: backing every outcome across bookmakers

Arbitrage betting (arbing, surebets) is backing every outcome of an event with different bookmakers when the implied probabilities in their odds add up to less than 100%. The player profits whatever the result, and the cost falls on the bookmaker whose price lagged behind the market.

Yevhen SychovOctober 2026

Formula and example

An arb exists if the sum of 1 / odds across all outcomes is below 100%One bookmaker offers 2.10 on the first tennis player, another offers 2.00 on the second: 47.6% + 50% = 97.6%. Stakes of €48.78 and €51.22 return €102.44 whatever the result.

Each bookmaker has its own line and its own margin. An arb appears when one of them lags behind the market: it did not update the price after news, made a mistake on a niche market or posted a promo price. The arber almost always plays against the stalest price.

How arbers are spotted and why they get limited

  • A better-than-market price on almost every bet: odds higher than most bookmakers offer at the same minute.
  • Odd stake amounts: €48.78 instead of €50, calculated for a specific arb.
  • Bets right before a line move: your price is still the old one, the market's is already new.

The arber does not depend on the result: each of their bets is placed against an error in the line and wins on average. That is why the account gets its limits cut, like a sharp. If the rules have no specific clause on arbing, an accepted bet is settled, and the new limit applies to future bets.

Arbing with bonus money

A free bet or bonus goes on one outcome, and the other outcomes are covered with real money at another bookmaker. That way the player extracts the value of the bonus almost risk-free.

  • Opposite bets on one account or on linked accounts are visible straight away. The bonus terms prohibit them, and breaking that clause is already bonus abuse.
  • A hedge at another bookmaker cannot be seen. The protection is terms that cut the value: minimum odds and a wagering requirement on free bet winnings.
  • Without a clause in the terms, the winnings stand under the rules: change the terms of future offers instead.

Common mistakes

  • Boosts without a stake limit. Boosted odds above the market are a ready-made arb for anyone who covers the other outcome at a competitor.
  • Voiding a bet for arbing without a clause in the rules. That means a dispute, a complaint and a hit to reputation.
  • Limiting accounts but not fixing the line. The source of arbs is a slow price. Until it gets faster, new arbers will take the place of the old ones.
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