Arbitrage, Middles & Scalps
Cross-book line discrepancies are mathematical free money — when you can find them. The math is wired; once a multi-book feed is connected (Pinnacle / DK / FanDuel / MGM), opportunities flow in here.
| Market | Side A | Side B | Implied Sum | Profit % | Stake Split |
|---|
A true arb pays a small but guaranteed profit. The "Stake Split" tells you the optimal % to put on each side so payouts equalize. Real-world snag: books cap bet size and ban frequent arbers. Use these sparingly, mix in -EV plays to look like a normal bettor.
| Market | Type | Side A | Side B | Middle Window |
|---|
A middle is when you can bet OVER at one line and UNDER at another. If the game total lands BETWEEN them, both bets win — a "middle hit." You risk a small loss (the combined juice) and win a payoff if it middles. In MLB, totals middles cash ~7% of the time historically, which is enough to make zero-juice middles +EV.
| Market | Side A | Side B | Combined Vig |
|---|
Standard markets carry 4-5% vig. By splitting one side at book A and the other at book B, you can routinely find pairings with under 3% combined vig — meaning your model only needs a small edge to clear it. Pinnacle is usually one side of every low-vig pair.
Arb betting looks too good to be true on paper. In practice:
- Limits matter. A $50 arb is real money in volume, but most books will cap your stake at $200-$1,000 within a few weeks of betting only arbs.
- Books talk to each other. A line move on Pinnacle triggers immediate moves on others. Arb windows often last 30-90 seconds before they close.
- Bonuses change the math. When books offer "bet $200, get $200" promos, the +EV math on arbs becomes massive temporarily. Hunt these.
- Pinnacle is your friend. They have the sharpest book and accept arbers. Most arb sides should be there.
- Mix in action. If 100% of your bets are arbs, you'll be banned. Sprinkle in -EV parlays so you look square. Cost of doing business.