National Bank Open: Marta Kostyuk vs Iga Swiatek

Platform comparison

Market context

The National Bank Open meeting between Marta Kostyuk and Iga Swiatek is priced as a Swiatek lean, with the crowd at 64% for a Swiatek advance. That sits comfortably in line with the head-to-head record: Swiatek leads the series 4-1 in TennisStats’ latest listing, and she has won the last four meetings, including straight-sets wins on hard courts in Cincinnati in 2024 and Indian Wells in 2024.[2][13]

That probability also fits the broader pattern on similar markets, where prior head-to-head dominance usually matters more than one-off upsets. Swiatek has controlled the matchup on both clay and hard courts, while Kostyuk’s lone recent win in the 2026 French Open is the main counterpoint for traders, showing the Ukrainian can still disrupt the matchup when conditions suit her.[2][10] In practical terms, a low- to mid-60s price implies the market is leaning on Swiatek’s historical edge rather than treating the contest as close to 50-50.[4][15]

The main catalyst to watch is whether the scheduled Toronto match actually goes ahead as planned, because any non-completion, cancellation, or delay beyond the market’s settlement window pushes resolution towards a tie. For traders, the key dependency is the official order of play and any last-minute injury or withdrawal updates from the tournament, with live match listings already appearing on score services ahead of the expected August 9 slot.[9][6] If the match starts, the market will mainly move on the first set pattern: a quick Swiatek hold-and-break start would reinforce the current lean, while an early Kostyuk surge would narrow it fast.

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.

Can prediction markets influence election outcomes?

Markets reflect expectations rather than create them. Studies show public-facing markets can anchor expectations, but don't influence the underlying outcome. Political markets are information, not advocacy.

How fast do political markets react to news?

High-liquidity markets move within seconds to minutes. A Trump tweet on the economy can shift the "Trump 2024" market 2-5 points before mainstream media has written anything.

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.