Arbitrage tracker

Every 15 seconds the tracker reads the live order books on Kalshi and Polymarket for every game priced on both, and checks whether buying one side on each venue (or both sides on one) costs less than the $1 the winner pays, after both venues' taker fees. Each continuous sighting is one episode. Capacity is the top-of-book size on the thinner leg. Observe-only: nothing is traded.

How close it gets · cheapest cover per game-hour

Closest right now

Episodes

Before automating, remember

• Settlement rules can differ between venues (tennis retirements/walkovers, postponements, NFL ties). A "both sides" position can lose on both legs.
• Leg risk: the second fill can move before it executes; arbs shorter than ~1 poll are often unfillable by hand.
• Venue access: prices come from Polymarket's international order book; check which Polymarket you can legally trade and that its prices match.
• Capital lock-up: money sits on both venues until settlement — weigh margin per day held, not per trade.
• Polling every 15s undercounts arbs that open and close faster than that.