The Prediction Markets

Stoiana vs Siniakova

Starts in 7 hKickoff
Traded
$8K
Venues
Polymarket, Kalshi
Prices updated
1 min ago
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What the markets expect

Katerina Siniakova 70%

Next is Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5 at 67.5%. The venues differ most on Stoiana (Polymarket 30.5%, Kalshi 32%), a 1.5-point gap.

Odds by venue

Consensus blends each venue’s last price, weighted by how much has traded there. Best Yes price is the cheapest ask across venues, and the payout is what a winning $100 stake returns before fees. Open a row for each venue’s contract name, bid and ask, and how closely their rules match.

Prices come from our regular polls of each venue, the oldest 3 min ago. Ages are as of when this page was built.

  • Polymarket
  • Kalshi
Katerina Siniakova
70%
Kalshi 70%polled, 1 min agoBest Yes 70¢ on Kalshi, $100 pays $143 (1.43x)
Kalshi
Contract
Katerina Siniakova
Last price
70%
As of
Polled 1 min ago
Buy Yes
70¢
Sell Yes
69¢
$100 on Yes pays
$143 (1.43x)
Volume
$4K
Trade this on Kalshi
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
67.5%
Polymarket 67.5%polled, 3 min agoBest Yes 69¢ on Polymarket, $100 pays $145 (1.45x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 1 O/U 8.5
Last price
67.5%
As of
Polled 3 min ago
Buy Yes
69¢
Sell Yes
66¢
$100 on Yes pays
$145 (1.45x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
55%
Polymarket 55%polled, 3 min agoBest Yes 56¢ on Polymarket, $100 pays $179 (1.79x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Game Spread +/-3.5
Last price
55%
As of
Polled 3 min ago
Buy Yes
56¢
Sell Yes
54¢
$100 on Yes pays
$179 (1.79x)
Trade this on Polymarket
Completed Match
48%
Polymarket 48%polled, 3 min agoBest Yes 95¢ on Polymarket, $100 pays $105 (1.05x)
Polymarket
Contract
Completed Match
Last price
48%
As of
Polled 3 min ago
Buy Yes
95¢
Sell Yes
1¢
$100 on Yes pays
$105 (1.05x)
Volume
$100
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
48%
Polymarket 48%polled, 3 min agoBest Yes 96¢ on Polymarket, $100 pays $104 (1.04x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 2 O/U 9.5
Last price
48%
As of
Polled 3 min ago
Buy Yes
96¢
Sell Yes
—
$100 on Yes pays
$104 (1.04x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
48%
Polymarket 48%polled, 3 min agoBest Yes 96¢ on Polymarket, $100 pays $104 (1.04x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 2 O/U 8.5
Last price
48%
As of
Polled 3 min ago
Buy Yes
96¢
Sell Yes
—
$100 on Yes pays
$104 (1.04x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
48%
Polymarket 48%polled, 3 min agoBest Yes 96¢ on Polymarket, $100 pays $104 (1.04x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 2 O/U 10.5
Last price
48%
As of
Polled 3 min ago
Buy Yes
96¢
Sell Yes
—
$100 on Yes pays
$104 (1.04x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
47.5%
Polymarket 47.5%polled, 3 min agoBest Yes 48¢ on Polymarket, $100 pays $208 (2.08x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set Handicap +/-1.5
Last price
47.5%
As of
Polled 3 min ago
Buy Yes
48¢
Sell Yes
47¢
$100 on Yes pays
$208 (2.08x)
Volume
$2
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
45%
Polymarket 45%polled, 3 min agoBest Yes 46¢ on Polymarket, $100 pays $217 (2.17x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
Last price
45%
As of
Polled 3 min ago
Buy Yes
46¢
Sell Yes
44¢
$100 on Yes pays
$217 (2.17x)
Volume
$3
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
44%
Polymarket 44%polled, 3 min agoBest Yes 50¢ on Polymarket, $100 pays $200 (2.00x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 1 O/U 9.5
Last price
44%
As of
Polled 3 min ago
Buy Yes
50¢
Sell Yes
38¢
$100 on Yes pays
$200 (2.00x)
Trade this on Polymarket
Show 7 more outcomes
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
40.5%
Polymarket 40.5%polled, 3 min agoBest Yes 43¢ on Polymarket, $100 pays $233 (2.33x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 22.5
Last price
40.5%
As of
Polled 3 min ago
Buy Yes
43¢
Sell Yes
38¢
$100 on Yes pays
$233 (2.33x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
35.5%
Polymarket 35.5%polled, 3 min agoBest Yes 36¢ on Polymarket, $100 pays $278 (2.78x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 1 Winner
Last price
35.5%
As of
Polled 3 min ago
Buy Yes
36¢
Sell Yes
35¢
$100 on Yes pays
$278 (2.78x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
35%
Polymarket 35%polled, 3 min agoBest Yes 36¢ on Polymarket, $100 pays $278 (2.78x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Total Sets: O/U 2.5
Last price
35%
As of
Polled 3 min ago
Buy Yes
36¢
Sell Yes
34¢
$100 on Yes pays
$278 (2.78x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
35%
Polymarket 35%polled, 3 min agoBest Yes 41¢ on Polymarket, $100 pays $244 (2.44x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 23.5
Last price
35%
As of
Polled 3 min ago
Buy Yes
41¢
Sell Yes
29¢
$100 on Yes pays
$244 (2.44x)
Trade this on Polymarket
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
33.5%
Polymarket 33.5%polled, 3 min agoBest Yes 37¢ on Polymarket, $100 pays $270 (2.70x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 2 Winner
Last price
33.5%
As of
Polled 3 min ago
Buy Yes
37¢
Sell Yes
30¢
$100 on Yes pays
$270 (2.70x)
Trade this on Polymarket
Stoiana
30.9%
Polymarket 30.5%polled, 3 min agoKalshi 32%polled, 1 min agoBest Yes 31¢ on Polymarket, $100 pays $323 (3.23x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova
Last price
30.5%
As of
Polled 3 min ago
Buy Yes
31¢
Sell Yes
30¢
$100 on Yes pays
$323 (3.23x)
Volume
$3K
Trade this on Polymarket
Kalshi
Contract
Mary Stoiana
Last price
32%
As of
Polled 1 min ago
Buy Yes
32¢
Sell Yes
31¢
$100 on Yes pays
$313 (3.13x)
Volume
$312
Trade this on Kalshi
Partial parity

Payoffs match in ordinary outcomes; see the rule differences below the table.

No arbitrage: the best bid elsewhere is 31¢, at or below the cheapest ask of 31¢.

Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
21.5%
Polymarket 21.5%polled, 3 min agoBest Yes 23¢ on Polymarket, $100 pays $435 (4.35x)
Polymarket
Contract
Japan Women's Open: Mary Stoiana vs Katerina Siniakova Set 1 O/U 10.5
Last price
21.5%
As of
Polled 3 min ago
Buy Yes
23¢
Sell Yes
20¢
$100 on Yes pays
$435 (4.35x)
Trade this on Polymarket

No cross-venue arbitrage right now: on every matched outcome, the best bid on one venue is at or below the cheapest ask on the other. Find markets with open spreads

Mostly the same bet: two differences

Where they differ

  • If the match is postponed: Kalshi resolves to a fair price if the match does not start within 48 hours of the scheduled time (tennis: not finished within two weeks); Polymarket stays open until the match is played and resolves 50-50 only if it is cancelled with no make-up (tennis: ~14 days).
  • Kalshi requires a ball to be played and pays the winner; Polymarket pays the player who advances, including on retirement. A pre-match walkover is a fair price on Kalshi, 50-50 on Polymarket.
Polymarket
Polymarket resolves via:
UMA optimistic oracle, source: wtatennis.com
Kalshi
Kalshi resolves via:
Kalshi (CFTC-regulated exchange), source: WTA
Show full rule comparison
  • If the match is postponed: Kalshi resolves to a fair price if the match does not start within 48 hours of the scheduled time (tennis: not finished within two weeks); Polymarket stays open until the match is played and resolves 50-50 only if it is cancelled with no make-up (tennis: ~14 days).
  • Kalshi requires a ball to be played and pays the winner; Polymarket pays the player who advances, including on retirement. A pre-match walkover is a fair price on Kalshi, 50-50 on Polymarket.
  • Trading closes Oct 30, 2026, 5:30 AM UTC on Polymarket and Nov 6, 2026, 4:50 AM UTC on Kalshi.

Summarized from each venue’s published rules; the venue’s own rules page is the final word.

How the odds have moved

The top 3 outcomes on both venues, with the consensus between them. Hover for exact values.

  • Katerina Siniakova
  • Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5
  • Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5

Order books

Each venue’s resting orders for the selected outcome’s Yes contract, side by side. Top of book streams live; depth refreshes every 15 seconds.

Polymarket

Polymarket doesn’t list Katerina Siniakova for this event.

Kalshi

Open on Kalshi ↗

Top of book

Connecting
Best bid
—
Spread
—
Best ask
—

Waiting for the first live quote…

Depth · top 8 levels

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Recent trades

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What your stake buys

Enter a stake to see where it buys the most after fees, using each venue’s live order book.

$
Buy

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Buys at the asks resting now (taker orders), cheapest after fees first, from order-book snapshots up to 15 seconds old. Fees: Kalshi 0.07 × price × (1 − price) per share, rounded up to the cent; Polymarket 0.05 × price × (1 − price) per share (sports rate). Fee calculator. Estimates only, not advice.

About this market

Live prediction market odds for "Stoiana vs Siniakova". Katerina Siniakova leads at 70%. Next is Japan Women's Open: Mary Stoiana vs Katerina Siniakova Match O/U 21.5 at 67.5%. $8K has traded across 17 outcomes on Kalshi and Polymarket. The market is expected to resolve by Nov 6, 2026.

Questions

What does the consensus price mean?

It is the price of a Yes contract that pays $1 if the outcome happens. A 14¢ price means traders put the chance near 14%. Where two venues list the same outcome, we blend their last prices, weighting the venue with more trading volume more heavily (neither counts for less than a quarter). When only one outcome can win, each venue’s prices add up to a little over 100% (its margin); the fair chance removes that margin so the outcomes add up to exactly 100%.

How is the payout worked out?

A Yes contract pays $1 if it wins, so at the best ask a $100 stake buys 100 ÷ ask contracts. At 18¢ that is about 555 contracts, paying $556 (5.56x) if Yes happens. Venue fees and price slippage on larger orders are not included.

Why do the venues show different prices?

Each venue has its own traders, fees and order book. Contracts can also settle on slightly different terms, which is why each row lists how closely the rules match.

Is a price gap an arbitrage?

Only when you can buy Yes on one venue below what someone pays for Yes on the other, after fees, and both contracts settle the same way. We show the executable bid and ask so you can check.

How fresh are these prices?

Venue prices refresh every few minutes, and the order book and live quotes stream continuously. Each venue’s card shows when we last observed it.

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