Cincinnati Open: Mary Stoiana vs Tereza Valentova

Platform comparison

Market context

Mary Stoiana and Tereza Valentova have already been listed as played or completed in recent scoreboards, with Valentova the stronger pre-match and live favourite and at least one source showing her leading by ranking and projections before the match settled. The market’s 0% YES reading fits a scenario where the field has effectively moved away from Stoiana, as the Czech player was consistently priced as the likelier winner on the hard courts in Cincinnati.

For comparison, tennis markets often swing sharply when a scheduled first-round match is completed, moved, or shown as final on live score feeds; once a winner is recorded, the resolution risk usually drops to the narrow questions of whether the entry is correctly matched to the official result or whether a void condition applies. If the contest had instead been delayed, abandoned, or left without a completed result, the market’s 50-50 fallback would have been the key reference point rather than pre-match pricing.

The immediate catalysts are the official order of play, live scoring updates, and any tournament-side adjustment to the women’s singles draw at Cincinnati, which is still running through the first round and into the next stages this week. Traders should watch for whether the fixture is confirmed as completed, whether any retirement or walkover is logged, and whether the relevant match page is updated to show a finished score rather than an “upcoming” state.

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 Prediction Today. 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%.