A prediction market lets you trade YES or NO contracts on real events: elections, Fed decisions, sports, crypto moves. Prices are set by traders, settle at $1.00 or $0.00, and read as an implied probability — no odds table required. We explain the mechanics, compare the platforms and track where they are legal.
| Platform | Regulation | US access | Trading fees | Markets | Best for |
|---|---|---|---|---|---|
| Kalshi CFTC DCM | CFTC-regulated exchange | Yes — all 50 states (sports contracts contested in some) | ≈ 0.07 × C × P × (1−P), max 1.75¢/contract | Elections, economy, sports, crypto, weather | US traders who want fiat rails and regulated venues |
| Polymarket USDC | Global exchange + CFTC-regulated US venue (Polymarket US) | Yes via Polymarket US app; global exchange not for US persons | 0% global · small taker formula on US venue | Deepest catalog: politics, sports, crypto, culture | Crypto-native traders who want market breadth |
| Robinhood CFTC venue | Event contracts on CFTC-regulated facilities | Yes — selected states, expanding | Commission shown at order entry | Sports, economics, headline events | Existing brokerage users trying event contracts |
| PredictIt $850 cap | CFTC no-action letter (research exemption) | Yes — US political markets | 10% of profits + 5% withdrawal | US politics and elections only | Small-stake political junkies and researchers |
Fees and availability verified October 2026 from published fee schedules and regulator filings; sports-contract access is being litigated in several states. Platforms are reviewed independently — we hold no positions in any of them.
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Event contracts on Kalshi and Polymarket US trade on CFTC-regulated exchanges, which makes them federally legal for US residents — though several states are fighting sports-related contracts in court and the CFTC has proposed new rules for 2026. The global Polymarket exchange remains off-limits to US persons. See the legal guide for the verified map.
Kalshi fits US users who want dollar deposits and a single CFTC-regulated venue; Polymarket fits crypto-native traders who want the widest catalog and no trading fees on its global exchange. The full comparison covers fees, custody and settlement rules.
Contracts settle at $1.00 if the event happens and $0.00 if it doesn't — so $0.63 is a 63% implied probability, and the NO side costs $0.37. The odds school guide shows the conversions worth memorizing.
US profits from event contracts are generally reportable income, and regulated venues issue tax documentation where required. Treatment differs by country — keep full records and confirm with a tax professional. Our explainer covers the basics.