National Bank Open: Elise Mertens vs Anna Bondar

Platform comparison

Market context

Elise Mertens against Anna Bondar at the National Bank Open looks like a straightforward favourite-versus-underdog match on paper, but the contract’s **100% YES** crowd price implies the market is treating Mertens as an almost certain winner rather than merely a strong favourite. That is materially more bullish than the broader tennis data: H2H records show Mertens leading Bondar 2-0 overall across the sources provided, and one odds feed lists Mertens around **-409** in implied pricing, which is consistent with a heavy favourite rather than a lock.[1][2][6][13]

The historical frame is still important because these players have met before on hard courts, and Mertens won that Toronto match in straight sets in 2022.[1][5][13] Recent season splits also point in the same direction, with Mertens’ 2026 win rates ahead of Bondar’s across several data providers, while ranking snapshots place Mertens around the mid-20s and Bondar around the high-70s/low-80s.[2][7][10] Even so, a 100% prediction-market price sits above what sportsbook-style moneyline pricing usually implies for a top-30 player against a lower-ranked opponent, so the main question is not who should be favoured, but whether the market is overconfident relative to the true upset risk.

Traders should watch for the final order of play, because the contract only resolves to 50-50 if the match is not played, is tied, or is delayed beyond seven days without a winner.[11] The relevant live listings suggest the match was being tracked for 6 August, but tennis schedules can move quickly with weather, court assignment changes, and late withdrawals, so any official rescheduling or retirement scenario matters more here than normal pre-match form noise.[10][11][14] If the match starts, settlement depends on who advances, so retirement and walkover language in the tournament feed will be the key catalyst rather than in-play scoreline alone.

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 Best Prediction Markets 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.

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.

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.

What are the best prediction markets for UK traders in 2026?

For UKGC-regulated markets: Betfair Exchange (sports, politics) and Smarkets (sports, politics, lower commission than Betfair). For broader global event prediction: Polymarket (deepest liquidity, 0% fee, USDC settlement). For US-regulated option: Kalshi (USD, limited UK payment options). Most serious UK traders use a combination of Betfair for regulated sports and Polymarket for broader markets.