Lock guaranteed profit across books.

Sportsbook A prices the Lakers at +120; Sportsbook B prices the Celtics — the other side of the same game — at +105. Both can't be right: the two implied odds add up to less than 100%, so the books disagree in your favor. Stake $100 on the Lakers (+120 returns $220) and $107 on the Celtics (+105 returns ~$220). You've risked $207 and collect ~$220 whoever wins— a locked ~$13 profit on either outcome. That's the point of an arb: profit on both sides, not one.

That's arbitrage. The catch: arb windows close in seconds. The books re-price as soon as the disagreement is spotted by the market. Players who only ever place arb bets get limited fast on the aggressive books — the books know arb players don't lose, and they don't want to take that action.

Whet flags arb windows the moment they open, computes the optimal stake split given a fixed bankroll, and tracks which books you've already used recently. If you've been arbing FanDuel three times this week, the scanner routes this week's new arb to a different book to keep your accounts healthy.

The arb-rate target is configurable: 1% per bet is the conservative default (low-flag, sustainable); 2%+ is the aggressive setting that'll find more action but shortens account life. Whet shows the trade-off explicitly, not as a hidden lever.

Arbitrage doesn't mean “risk-free.” Limits drop. Books void bets when they think a line was mispriced. Bonus funds don't always count toward the lock. Two markets can be correlated in ways the calculator doesn't see (player props with shared rosters). Real arb in 2026 is a managed-risk strategy, not a printing press.

Whet ships the arb scanner with full transparency on these frictions: per-book limit history, void-rate signals, and flag-detection so you can pause arbing on a book before it cuts you off entirely. The math says +EV; the operations say “manage your accounts.”