National Bank Open: Elise Mertens vs Anna Bondar

Platform comparison

Market context

Polymarket is pricing Elise Mertens to advance at 100% YES, which is materially above the prices implied by other tennis books and models for the same National Bank Open match. At the other venues, Mertens is generally a clear favourite rather than a lock: BetUS lists her around -310, average bookmaker odds on TennisTemple sit near 1.35 for Mertens and 3.21 for Anna Bondár, and Tennis.com shows a projected winner split of 72% to 28%.[2][1][4]

For context, that leaves this contract sensitive to the usual tennis-event mechanics rather than just the pre-match ranking gap. Mertens is the higher-ranked player, listed around WTA No. 20 versus Bondár at No. 78, and they have already met before, with Mertens winning their 2022 National Bank Open encounter in straight sets.[1][16] On comparable models, the pricing still sits below certainty: String Tension’s Elo forecast gives Mertens 80.4%, while a Kalshi market on the same matchup has been trading around 75¢ for Mertens YES, both well short of a 100% outcome.[3][18]

The main catalysts for traders are draw changes, walkover risk, and match completion rather than form alone. The listed start times vary by feed, with the match shown as upcoming on 5 August or 6 August depending on the sportsbook calendar, so any official scheduling shift or delay matters because this market settles 50-50 if the match is not played, ends level, or drifts beyond the settlement window without a winner.[2][4][18] Under Polymarket’s on-chain setup, the trade is still just USDC on Polygon backing conditional tokens, so the key question is whether Mertens actually advances on court or whether the event gets pushed into a non-standard resolution path.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track National Bank Open: Elise Mertens vs Anna Bondar 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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 Alternative UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

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%.