National Bank Open: Tallon Griekspoor vs Matteo Arnaldi

Platform comparison

Market context

Tallon Griekspoor and Matteo Arnaldi are set for another direct meeting, and the market’s 61% price for Griekspoor points to a modest lean rather than a dominant edge. The last completed meeting between the pair came at Roland Garros in May, where Arnaldi won 3-1 on clay, so the recent head-to-head record still favours the Italian despite Griekspoor’s stronger overall match-win rate over the last 52 weeks.[1][2][12]

That history is a useful guide, but only up to a point: the previous result was on clay, while this contest is in Montreal on hard court, where the surface profile is different and the sample between them is tiny. Griekspoor’s recent body of work has been a touch stronger overall, with a 55.2% win rate across the past 52 weeks versus Arnaldi’s 47.9%, yet Arnaldi has handled top-50 opposition at a low rate, winning only 6 of 20 such matches in that period.[2]

For traders, the main catalysts are straightforward: confirm whether the National Bank Open schedule holds, whether either player is moved on court order, and whether any late injury, retirement, or withdrawal news lands before the listed start. If the match is delayed or abandoned, the market’s resolution rules matter more than the pre-match price, because a postponement beyond seven days or a non-played fixture would push settlement to 50-50.[8][5]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track National Bank Open: Tallon Griekspoor vs Matteo Arnaldi 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

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%.