What is arbitrage?

Arbitrage (“arbing”) is betting all possible outcomes of an event at different sportsbooks whose prices, taken together, guarantee a profit no matter what happens. It exists when books disagree enough that the combined de-vigged probabilities fall below 100%. Arbitrage is genuinely risk-free in theory, but the margins are tiny (often under 2%), the windows close in seconds, it demands large bankrolls across many accounts, and books quickly limit bettors they suspect of arbing.

Convert every outcome's best available price to implied probability and add them. If the total is below 100%, an arbitrage exists and you can stake each side proportionally to lock a profit. In practice you're hunting for two books whose lines disagree — one posts a stale number, another has moved — which is the same market inefficiency behind a middle, only guaranteed rather than conditional.

Arbs are real but hard to run at scale: profits per arb are small, prices move before you finish placing both bets, and books restrict accounts that only bet arbs. For most people the durable lesson is what arbitrage reveals — that shopping lines across books for the best price is the one edge available to everyone, the same principle behind closing line value.

What is arbitrage betting?Arbitrage, or arbing, is betting all outcomes of an event at different books whose combined prices guarantee a profit regardless of the result. It works when the summed de-vigged probabilities fall below 100%.

Is arbitrage betting risk-free?In theory yes, but in practice margins are tiny, lines move before you can place both bets, it needs large bankrolls across many accounts, and books quickly limit suspected arbers.

Why do sportsbooks ban arbers?Because arbitrage extracts guaranteed profit from their pricing errors. Books monitor for the pattern and restrict stakes or close accounts of bettors who consistently arb.