Sports replay: Kalshi vs Polymarket US
Recorded order books from both venues on one clock. Game winners, taker fees included.
Kalshi
Polymarket US
Arbitrage gap
Inside a gap
Click a green dot above. Top: each venue's price. Bottom: what one contract of each side costs, fees in. Under $1.00 is locked profit.
Pick a gap.
Data: Layer's tick recorders (every book change on Kalshi and Polymarket US), replayed with
research/sports-gaps-2026-11. Times are when Layer received each change; the two recorders' clocks can differ by 20–100 ms.
A gap = buying both sides of the same game across the two venues for under $1 after both venues' taker fees, at the depth on the books.