Platform comparison
| Platform | YES odds | NO odds | Fee | KYC | Settlement | |
|---|---|---|---|---|---|---|
Polymarket (via Trump Prediction) Pick polygram.ink (preferred broker) |
88% | 12% | 0% (USDC on-chain) | No-KYC up to $1,500 | USDC, auto via UMA oracle | Live odds → |
Polymarket (direct) polymarket.com |
88% | 12% | 0% | Geo-blocked in US/UK/EU | USDC, on-chain | Live odds → |
Kalshi kalshi.com |
— | — | Up to 7% per trade | US-only, KYC required | USD | Live odds → |
Betfair Exchange betfair.com |
— | — | 2-5% commission | Full KYC from first trade | GBP / EUR | Live odds → |
Manifold Markets manifold.markets |
— | — | Play-money (mana) | None — play-money | Mana (no cash-out) | Live odds → |
Outcome probabilities
Current market-implied probability for each outcome, from the live order book.
| Outcome | Probability |
|---|---|
| US Open ATP: Ben Shelton vs Tallon Griekspoor | 88% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 2 Winner | 78% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 1 Winner | 75% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set Handicap +/-1.5 | 73% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 3 Winner | 71% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Total Sets: O/U 3.5 | 51% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Match O/U 36.5 | 51% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 1 O/U 10.5 | 51% |
| Completed Match | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 1 O/U 8.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 2 O/U 8.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Game Spread +/-5.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 1 O/U 9.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 2 O/U 9.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 4 Winner | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 2 O/U 10.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 3 O/U 8.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 3 O/U 9.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 3 O/U 10.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 4 O/U 8.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 4 O/U 9.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set 4 O/U 10.5 | 50% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Set Handicap +/-2.5 | 48% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Match O/U 38.5 | 47% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Match O/U 40.5 | 41% |
| US Open ATP: Ben Shelton vs Tallon Griekspoor Total Sets: O/U 4.5 | 19% |
Market context
Market consensus: 88% chance of us open atp: ben shelton vs tallon griekspoor. Prediction markets aggregate real capital to produce this probability signal. This market refers to the tennis match between Ben Shelton and Tallon Griekspoor in the US Open ATP, originally scheduled for August 30, 2026 at 11:00AM ET. This market will resol…
Methodology
Political prediction markets differ structurally from sports betting: thinner liquidity, longer settlement windows, higher sensitivity to single news events. This page shows the live Polymarket quote for US Open ATP: Ben Shelton vs Tallon Griekspoor plus platform attributes for the three reference venues, so you can see at a glance where the deepest market for this question sits.
Resolution & payout
Political markets typically settle on official candidate or agency confirmation. Polymarket uses UMA Optimistic Oracle: a proposer posts the outcome with a bond, the two-hour window opens, then the smart contract pays USDC.
Kalshi settles USD via CFTC clearinghouse, with clearly defined resolution sources (e.g. AP race calls for elections). Betfair settles after the official outcome is registered with the league or agency. Manifold is play-money.
UK Frequently Asked Questions
- How accurate are political prediction markets?
- Historically more accurate than polls. Polymarket's Brier score on US 2024 elections was ~0.11 — better than 538 (~0.14) and every mainstream poll. Markets aggregate information with real skin in the game.
- Can prediction markets influence election outcomes?
- Markets reflect expectations rather than create them. Studies show public-facing markets can anchor expectations, but don't influence the underlying outcome. Political markets are information, not advocacy.
- How fast do political markets react to news?
- High-liquidity markets move within seconds to minutes. A Trump tweet on the economy can shift the "Trump 2024" market 2-5 points before mainstream media has written anything.
- Are political prediction markets legal in my country?
- It varies. They sit in legal gray areas in most jurisdictions. Polymarket is geo-blocked from US/UK/EU; some broker frontends have a different geo footprint. Trade only with capital you can afford to lose, and only if you understand the legal status in your jurisdiction.
- Are UK election prediction markets available from the UK?
- Yes. Betfair Exchange and Smarkets offer UKGC-regulated UK election markets (seat counts, party share, constituency results). Polymarket also lists UK election contracts with deeper global liquidity. Betfair winnings are typically tax-free for UK individuals; Polymarket profits are subject to HMRC CGT.
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