National Bank Open: Marta Kostyuk vs Madison Keys

Platform comparison

Market context

Marta Kostyuk against Madison Keys is a National Bank Open hard-court match-up where the market is effectively pricing a slight Keys edge, with crowd-implied probability at 55% YES. That sits in line with the published head-to-head: Keys leads 2-0, both wins coming in straight sets at Wimbledon in 2023 and 2024, so the historical signal favours Keys even though those meetings were on grass rather than hard court.[1][7][13]

For a programmatic trader, the cleanest read is to treat the 55% as a modest favourite signal rather than a strong one. Keys has the stronger career profile and recent win record in the surfaced stats, while Kostyuk’s route to an upset would usually depend on serving well, extending rallies, and converting any dip in Keys’ first-serve level.[1][5][14] Comparable H2H pages also show Keys taking four of the five sets across the pair’s meetings, reinforcing that the market is not starting from a coin-flip baseline.[3][11]

Catalysts to monitor are straightforward: official match start time, any court-order changes, and whether the fixture is actually completed inside the settlement window. The market rules matter here because if the match is not played, ends tied, or is delayed more than seven days from the scheduled date without a winner, it settles 50-50; if play begins but stops, advancement still determines the outcome.[User prompt] Live score and fixture feeds already list the match for 6 August 2026, so the main dependency is whether the tournament schedule holds and whether either player withdraws or advances by walkover.[9][14][15]

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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 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.