National Bank Open: Marta Kostyuk vs Iga Swiatek

Platform comparison

Market context

Marta Kostyuk against Iga Swiatek in the National Bank Open is pricing like a modest Swiatek favourite, with the market implying **44%** on Kostyuk. That leaves the consensus leaning to Swiatek, but not overwhelmingly so; for a trader, the live question is whether the number reflects a genuine upset chance or simply the usual premium attached to Swiatek’s level on hard courts.

The historical frame still points towards the favourite. Swiatek leads the head-to-head comfortably, with multiple databases showing a 4-1 or 3-0 edge depending on whether one recent 2026 French Open result is included, and the meetings that are clearly listed were mostly straight-sets wins for Swiatek, including 6-2 6-2 in Cincinnati in 2024.[2][3][4][5] That matters because this market is less about raw reputation than whether Kostyuk can break a pattern: Swiatek has generally controlled the matchup, while Kostyuk’s case rests on making the contest more physical and forcing a higher-variance baseline battle than the prior hard-court meetings.

The main catalysts are straightforward: whether the draw holds, whether both players are physically intact after their recent tournament schedules, and whether the match actually starts on the expected day. The market’s settlement rules mean a late cancellation, extreme delay, or non-completion can push the result to 50-50, so pre-match confirmation is important if the listed August 9 slot slips.[10] For context, the latest reporting around Swiatek has centred on her continuing run of results rather than any specific injury issue, which supports her status as the side the crowd is respecting; any late withdrawal news, schedule reshuffle, or weather disruption would be the most obvious contrarian angle for this price.[13][15]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews National Bank Open: Marta Kostyuk vs Iga Swiatek across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Who Will Win 2026, which mirrors the Polymarket order book at 0% fees.

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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

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.