National Bank Open: Caty McNally vs Alexandra Eala

Platform comparison

Market context

Caty McNally’s match with Alexandra Eala at the National Bank Open is being priced like a clear underdog spot, with the crowd implying just **13%** for McNally even though several tennis books and models have Eala closer to the mid-60s or low-70s in win probability. Polymarket’s own comparable National Bank Open listing has Eala around **70%** and McNally around **31%**, while other modelled prices are broadly similar, which suggests the current contract is materially cheaper than the wider market consensus rather than an isolated outlier.[6][12][17]

That gap matters because single-match tennis markets can reprice sharply on late draw changes, warm-up reports, or even confirmation that the match is going ahead on schedule, especially when the settlement rule includes a 50-50 outcome if the match is not played or is pushed beyond the delay window. The most relevant catalyst is the official status of the Toronto fixture itself, since the listed start time has already shifted across sources and live pricing is still being updated, leaving room for a binary move once the opening server is confirmed.[3][10][11] For crypto traders, the practical angle is that the market settles in USDC, so position sizing and exit timing matter more than the headline probability when the event is near-dated and subject to non-play contingencies.

On-chain, this is the kind of short-dated sports contract where liquidity can be thin and spot price can move faster than the underlying tennis probability if BTC or ETH risk sentiment changes intraday. If wider crypto markets are firm, traders often have more capacity to lean into mispriced favourite/underdog extremes; if funding turns negative or whale flows hit the majors, some participants reduce exposure across prediction markets rather than hold until settlement.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — sit alongside as off-chain reference points so you can see how the contract translates across regulatory and settlement regimes.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

What are crypto prediction markets?

Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

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%.