National Bank Open: Marta Kostyuk vs Iga Swiatek

Platform comparison

Market context

Polymarket has this contract at **44% YES** on USDC, so the market is pricing Marta Kostyuk as an underdog against Iga Swiatek rather than a live coin flip. On Polymarket’s Polygon-based conditional-token setup, the share settles to the named player only if the WTA result is final; if the match is not played, ends level, or slips beyond the contract’s seven-day delay rule without a winner, it reverts to 50-50.

That price sits below the mainstream pre-match view. Tennis.com’s match page currently gives Swiatek a **57% projected win chance** versus Kostyuk’s 43%, while tournament and live-score listings show the fixture as a round-of-16 meeting on Centre Court in Toronto.[2][1][7] The historical frame is mixed: Swiatek leads the head-to-head overall and has been stronger on hard courts in past meetings, but Kostyuk’s recent upset over Madison Keys in Toronto shows she is not priced as a passive participant in this draw.[3][18]

For traders, the key catalysts are not abstract form narratives but concrete match mechanics: official start-time changes, whether play actually begins on Centre Court, and whether the winner is completed on the day or pushed by suspension, rain, or scheduling congestion. The National Bank Open’s own day-by-day reporting confirms Swiatek has already advanced through earlier rounds and that the Toronto event runs through 16 August, so any late reshuffle in the women’s draw can matter directly to settlement timing.[9][17] If the match starts, Polymarket still resolves on the player who advances, so in-play abandonment risk remains central.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track National Bank Open: Marta Kostyuk vs Iga Swiatek across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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%.