National Bank Open: Marta Kostyuk vs Iga Swiatek

Platform comparison

Market context

Iga Swiatek’s match with Marta Kostyuk at the National Bank Open is priced as a fairly even contest, with the market implying a narrow Swiatek edge at 44% YES on Kostyuk. The main anchor is their head-to-head history: Swiatek has dominated the series overall, with multiple stats sites showing her ahead either 3-0 or 4-1 depending on how they are counting recent meetings, and her wins have generally been in straight sets.[2][3][4]

That history matters, but it does not make Kostyuk a long shot in outright market terms because the recent sample includes a French Open meeting in 2026 where Kostyuk won in straight sets, breaking the earlier pattern.[3][10] Comparable cases in tennis markets often move away from the raw head-to-head when one player has a recent win on a different surface, especially if the event is on hard court and the players’ recent form is mixed rather than one-sided.[1][9]

For traders, the key catalyst is whether the scheduled match is actually played on time and under the original draw path, because tennis markets can flip to a split result if there is a cancellation, tie, or a delay beyond the settlement window rules in the market description. The most relevant live read is the event schedule and any late tournament announcements around court assignments, injury status, or walkover risk; recent match listings from Flashscore and Sofascore are the best indicators of whether this pairing remains intact and which player is favoured if it does.[6][8]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Political prediction markets differ structurally from sports betting: thinner liquidity, longer settlement windows, higher sensitivity to single news events. This page shows the live Polymarket quote for National Bank Open: Marta Kostyuk vs Iga Swiatek plus platform attributes for the three reference venues, so you can see at a glance where the deepest market for this question sits.

Resolution & payout

For political markets the resolution source is decisive. Polymarket defines a concrete source per contract (e.g. AP, Reuters, official electoral commission) and uses the UMA Optimistic Oracle as the on-chain dispute mechanism. With a clearly defined outcome the USDC payout lands within minutes of the final confirmation.

UK Frequently Asked Questions

How accurate are political prediction markets?

Historically more accurate than polls. Polymarket's Brier score on US 2024 elections was ~0.11 — better than 538 (~0.14) and every mainstream poll. Markets aggregate information with real skin in the game.

What resolution source is used for elections?

Polymarket defines the source per contract — usually Associated Press (AP Race Call), Reuters or the official electoral commission. The source is stated in contract details before the market opens.

Which platform has the deepest political liquidity?

Polymarket — by far. US 2024 presidential volume was ~$3.5B vs Kalshi (~$200M) and Betfair (~$120M). Where Polymarket is geo-blocked, brokers like Trump Prediction route into the same order book at 0% fees.

Why do Polymarket and Kalshi differ on elections?

Kalshi must follow CFTC compliance — strict definitions, clear resolution sources, US citizens only with KYC. Polymarket operates globally without CFTC oversight — deeper liquidity, but also higher regulatory risk.

Are UK election prediction markets available from the UK?

Yes. Betfair Exchange and Smarkets offer UKGC-regulated UK election markets (seat counts, party share, constituency results). Polymarket also lists UK election contracts with deeper global liquidity. Betfair winnings are typically tax-free for UK individuals; Polymarket profits are subject to HMRC CGT.