US Open, Qualification WTA: Tamara Zidansek vs Guiomar Maristany

Platform comparison

Market context

Tamara Zidanšek and Guiomar Maristany Zuleta de Reales met in the US Open women’s singles qualifying second round on 26 August, with the match listed on Court 16 and already recorded as completed on major live-score pages. Zidanšek came through a three-set first-round win over Laura Samson, while Maristany also advanced through her opening qualifier, so the market is anchored to a live qualification path rather than a speculative fixture.

For probability read-through, a 100% crowd price usually reflects one of two states: either the result has already been incorporated by the market, or the underlying event has effectively settled through match completion data. In comparable qualifying markets, once a second-round scoreline is posted, the main risk shifts away from tennis form and towards event-data integrity: whether the result is final, whether any walkover or retirement is later reclassified, and whether the market’s settlement logic matches the official tournament record.

A power-user would treat this as a dependency check, not a handicapping problem. The key triggers are the official US Open order of play, live scoring status, and any late amendments to qualifying results before the settlement window closes on 2 September; if the match was not played as scheduled, or if the result is overturned by an administrative correction, the market can fall back to its tie rule. Programmatically, the sensible workflow is to monitor official match status, confirm the completed scoreline against a second source, and only then let any automated conditional order or copy-trade instruction resolve.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

UK Frequently Asked Questions

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Bot UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.