What is arbitrage betting

How do you bet both sides and still win?

When two books disagree enough, backing both sides returns more than it costs. At +110 and +105 the implied probabilities sum to less than one, which is a 3.73% return on turnover whatever happens.

The maths is one line. The hard parts are the two nobody writes about.

The price may already be gone. Between the screen showing a quote and your bet landing sit the poll interval, the network and you. A quote that looks 10 seconds old on a feed running 5.4 seconds behind is really 15.4, and its chance of still being there is 84% rather than 89%. Miss one leg and you are not arbing, you are betting.

The stake gives you away. The exact solution here is 493.98 and 506.02. Nobody types that, and risk desks know it. Rounding afterwards breaks the lock because the legs are not symmetric — solving for round stakes directly gives 490 and 500, still guaranteed, for 2.35 of the 37.35. Stake one →