Learn/arb
What is arbitrage?
Two cashiers, one receipt
If you can buy every door and the prices still add to less than 100%, the leftover is locked profit — if both cashiers take the ticket.
5 min read
lock
Both doors, leftover in your pocket
Shop A
Home
2.20
stake $49
Shop B
Away
2.10
stake $51
1/2.2 + 1/2.1 = 0.931 — under 1.00. On $100 total, both results pay about $107. Leftover +6.9%.
Book A sells home at 2.20. Book B sells away at 2.10. 1/2.20 + 1/2.10 = 0.93. Seven cents on the dollar is the gap. Stake more on the shorter door so both payouts match.
The failure mode is one-sided: first book takes you, second moves. Now you just have a bet. That is why speed and the sizer on the Arb page matter more than the headline percent.
Books hate locks. Round the stake. Mix in ordinary tickets. Do not only fire 1% arbs from a fresh account. The edge is real; the welcome is not forever.
takeawayDutch the stake. Send the slow book first. A 9% live lock is almost always a phantom.