National Bank Open: Sara Bejlek vs Iga Swiatek

Platform comparison

Market context

Sara Bejlek against Iga Swiatek in the National Bank Open is a women’s singles match where the market’s **0% YES** implies the board is effectively pricing a Swiatek advance as certain. That is aggressive, but it reflects a clear favourite–underdog split: Swiatek won the pair’s only completed meeting at Roland Garros in straight sets, 6-2 6-3, and the head-to-head stands 1-0 to her.[1][3][8]

For context, this sort of near-zero pricing usually appears when a top seed meets a much lower-ranked opponent with a prior lopsided result, but it can still leave small value in a contrarian Bejlek position if the market is overreacting to reputation alone. Swiatek’s longer-term numbers are elite — tennisstats lists her at about 76% wins in 2026 and 74% over the last 12 months — while Bejlek is materially lower, which supports the consensus side.[1] Still, a 0% reading can be fragile in tennis because even heavy favourites can be exposed by early breaks, fitness issues, or a surface mismatch.

The main trader catalysts are straightforward: official order-of-play confirmation, any pre-match withdrawal or medical update, and whether the fixture starts on time or is rescheduled inside the seven-day settlement window. The market description makes clear that if the match is not played, ends level, or is delayed beyond seven days without a winner, it resolves 50-50 rather than to either player, so scheduling changes matter as much as on-court form. The French Open result also showed Bejlek can generate pressure moments — four of five break points converted in that match — which is the kind of stat traders watch if they are looking for a live-path upset rather than a pre-match favourite stamp.[8][16]

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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 does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.