Platform Rules & Fees
The mechanics differ meaningfully between venues — not just the same market with a different logo.
| Platform | Settlement | Regulation | Resolution | Fees | US Access |
|---|---|---|---|---|---|
| Polymarket | USDC (crypto), on Polygon | Not a CFTC-regulated exchange | UMA optimistic-oracle dispute process | Makers: $0. Takers: category-dependent, roughly 0–2%, weighted toward 50¢ contracts, $0 on most geopolitics markets. | Historically restricted for US persons via terms of service / geoblocking |
| Kalshi | USD, bank-linked account | CFTC-regulated Designated Contract Market | Kalshi's own settlement sources per contract rules | round_up(0.07 × contracts × price × (1−price)) per trade — peaks near $1.75 per 100 contracts at a 50¢ price, published formula | US persons, KYC required |
| Betfair Exchange | GBP/local currency | UK Gambling Commission-licensed betting exchange | Betfair's own market rules per event | Commission on net winnings (varies by market/jurisdiction, historically single-digit percent) | Not generally available to US persons |
| PredictIt | USD | Operates under an academic/research no-action arrangement, not a full CFTC-regulated exchange | PredictIt's own rules, small-dollar per-contract position limits | Historically a fee on profits plus a withdrawal fee — check current terms, these have changed over time | US-focused, small position caps per trader |
| Manifold Markets | Play-money ("Mana"), not real currency | Not a regulated financial exchange — no real-money payout | Community-created markets, creator or moderator resolved | None — no real money changes hands | Open to anyone |
| Limitless Exchange | USDC (crypto), on-chain | Not a CFTC-regulated exchange — crypto-native, decentralized | Oracle-based (e.g. Chainlink reference price) or platform-adjudicated per market | AMM trades: flat 0.40%. Order-book (CLOB) trades: 0.40–3.00% buy / 0.42–1.50% sell depending on price — makers pay nothing, only takers. | Open to anyone with a crypto wallet; no explicit US restriction published |
| Smarkets | GBP, bank-linked account | UK Gambling Commission-licensed betting exchange | Smarkets' own market rules per event | Historically marketed as a flat 2% commission on net winnings — a simpler, lower headline rate than Betfair's tiered commission — check current terms before trading. | Not generally available to US persons |