Kalshi vs Polymarket on WTA tennis matches: where the prices disagree today
11 WTA tennis matches priced on both Kalshi and Polymarket right now, $290k traded in 24 hours. The widest disagreement is Katerina Siniakova at +$0.02. Updated every 45 seconds.
| Event | Outcome | Kalshi | Polymarket | Gap, + = Kalshi higher | Edge after fees | |
|---|---|---|---|---|---|---|
| Japan Women's Open: Magda Linette vs Katerina Siniakova Oct 21, 9:00 PM ET | Katerina Siniakova | $0.66 | $0.65 | +$0.02 | -3.14% | Kalshi · Polymarket |
| Ningbo Open: Sorana Cirstea vs Sara Bejlek Oct 21, 4:30 AM ET | Sorana Cirstea | $0.66 | $0.67 | −$0.01 | -3.12% | Kalshi · Polymarket |
| Ningbo Open: Alexandra Eala vs Diana Shnaider Oct 21, 10:00 PM ET | Diana Shnaider | $0.59 | $0.60 | −$0.01 | -3.21% | Kalshi · Polymarket |
| Ningbo Open: Leylah Fernandez vs Aliaksandra Sasnovich Oct 21, 3:00 AM ET | Leylah Fernandez | $0.68 | $0.67 | +$0.01 | -3.11% | Kalshi · Polymarket |
| Japan Women's Open: Antonia Ruzic vs Kayla Day Oct 21, 9:00 PM ET | Antonia Ruzic | $0.50 | $0.51 | −$0.01 | -4.25% | Kalshi · Polymarket |
| Japan Women's Open: Mary Stoiana vs Moyuka Uchijima Oct 21, 9:00 PM ET | Mary Stoiana | $0.62 | $0.62 | +$0.01 | -4.18% | Kalshi · Polymarket |
| Ningbo Open: Ekaterina Alexandrova vs Marta Kostyuk Oct 21, 7:00 AM ET | Marta Kostyuk | $0.59 | $0.59 | $0.00 | -4.21% | Kalshi · Polymarket |
How this is built
Every event listed on both exchanges is matched outcome by outcome: games by team codes and date, multi-outcome markets by name. Prices are mid-market, in dollars on a contract that pays $1 if the outcome happens: Polymarket from its live order book, Kalshi from its public API. Gap is Kalshi minus Polymarket. Thin books (spread over $0.10) and near-certain favorites are excluded from this table.
Edge after fees
Buy one side on one venue and the other side on the other, both at the ask. Edge is $1 minus total cost minus taker fees, Kalshi ⌈0.07·P·(1−P)⌉ per contract and Polymarket 0.05·P·(1−P) on sports, as a percent of the $1 payout. Not advice; nothing here places orders.
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