US betting exchanges and prediction markets
Updated
An exchange lets you buy a yes or no contract on a game’s result from another trader, typically at a price between 1 and 99 cents; the contract pays $1 if it wins. SlateProof tracks four US exchanges (Kalshi, Polymarket US, Novig, ProphetX) on equal terms with the sportsbooks, because they are where an arbitrage or a promo hedge often finds its other leg.
Exchanges at a glance
| Exchange | States and DC where listed | Of those, contested | Minimum age | Taker fee on pregame sports |
|---|---|---|---|---|
| Kalshi | 47 of 51 | 12 | 18+ | 7% × price × (1 − price) per $1 contract, up to about 1.75¢ |
| Polymarket US | 40 of 51 | 4 | 18+ | 6.95% × price × (1 − price) per $1 contract, up to about 1.74¢ |
| Novig | 48 of 51 | 6 | 21+ | No taker fee on pregame sports (as researched) |
| ProphetX | 50 of 51 | 2 | 18+ | 2% of net winnings |
Availability checked October 5, 2026; fees checked October 6, 2026. “Contested” marks states where a court ruling, cease-and-desist or lawsuit about exchange sports contracts is pending, so access can change quickly.
Exchange pages
Kalshi
Kalshi is listed in 47 of 51 jurisdictions, 12 of them contested. Fee model, minimum age 18+, sign-up credit and settlement notes, checked 2026-10-05.
Novig
Novig is listed in 48 of 51 jurisdictions, 6 of them contested. Fee model, minimum age 21+, sign-up credit and settlement notes, checked 2026-10-05.
Polymarket US
Polymarket US is listed in 40 of 51 jurisdictions, 4 of them contested. Fee model, minimum age 18+, sign-up credit and settlement notes, checked 2026-10-05.
ProphetX
ProphetX is listed in 50 of 51 jurisdictions, 2 of them contested. Fee model, minimum age 18+, sign-up credit and settlement notes, checked 2026-10-05.
Keep going
Exchanges and sportsbooks work best together. See also the guides, calculators, state-by-state availability and sportsbooks, or open the live dashboard for today’s promo plays and arbitrage.