When two books disagree enough about a game, backing every outcome at the best available prices returns a profit no matter who wins. The math is bulletproof. The catch is everything around the math.
Spotting an Arb
Convert every outcome's best odds to implied probability and sum them. Under 100% means guaranteed profit: +110 on one side (47.6%) and +105 elsewhere on the other (48.8%) totals 96.4% — a 3.6% risk-free margin. Stakes are split so each outcome returns the same amount.
Where Arbs Come From
Slow line movement after news, promotional boosts, and genuine model disagreement between books — especially between sharp books like Pinnacle and slower recreational ones. Typical margins run 1-4%, so meaningful profit needs meaningful stakes and volume.
The Real Risks
Odds move mid-execution leaving you exposed on one side; voided bets on one book break the hedge; and most importantly, recreational books limit or close accounts that show arbing patterns. Round stakes, occasional recreational bets, and spreading volume across many books extend account life — but limits are eventually the cost of doing business.
Frequently Asked Questions
Is arbitrage betting legal?
Completely legal — it's just betting both sides at different businesses. Books dislike it and respond with account limits, not lawyers.
How much can arbers make?
Realistic full-time arbers grind 1-4% per cycle on high volume. Account limitations, not math, cap long-run earnings.