Who won the 2026 US Open? Alexander Zverev and Elena Rybakina, and neither was the crowd's favorite when this page was written. On September 3, Kalshi asked 42.5¢ for Carlos Alcaraz to win the men's title and 23.5¢ for Aryna Sabalenka to win the women's. A nine-model AI panel that priced both draws without seeing a market would pay 24.4% for Alcaraz and 17% for Sabalenka. Alcaraz lost in the quarterfinals to Ben Shelton, at 3:33 a.m. on September 9. Sabalenka lost the final to Rybakina, 6-4, 5-7, 6-2, on September 12. Zverev beat Shelton 6-3, 7-6(2), 5-7, 6-2 on September 13, and both title contracts settled.
By Jake Hari. This page was written on September 3 with the tournament in its first week, and the boards below are kept as they were priced that night, because that is what gets graded. The grading is here at the top; the argument it grades is below it. Nothing here is financial advice.
| Player | Kalshi, Sept. 3 | AI panel | What happened |
|---|---|---|---|
| Carlos Alcaraz | 42.5¢ | 24.4% | Lost the quarterfinal to Shelton in five sets |
| Alexander Zverev | 21.5¢ | 11.4% | Won the title |
| Ben Shelton | 8.5¢ | 8.5% | Beat Alcaraz and Tiafoe, lost the final |
| Aryna Sabalenka | 23.5¢ | 17% | Lost the final to Rybakina |
| Elena Rybakina | 5.5¢ | 9% | Won the title |
Kalshi prices are the September 3 midpoints from the boards below; the panel column is the blend from the same night. Results per ESPN's match reports, linked from the Shelton-Zverev and Sabalenka-Rybakina settled pages.
The two prices this page argued about both lost. The panel would not pay 42.5¢ for Alcaraz and said so in the headline; he went out in the quarters, and the 24.4% the panel had him at was closer to the truth than the crowd's 42.5¢. The panel's widest gap the other way on the women's board was Rybakina, 9% against a 5.5¢ price; she won it. The crowd had the men's winner better than the panel did, 21.5¢ against 11.4%, and neither side had Shelton, at 8.5¢ and 8.5%, anywhere near the final he reached. One tournament grades nothing on its own; the pattern this page was written to test, that the crowd pays too much for the name at the top of the board after a good week, held twice in one fortnight.
What follows is the September 3 edition as it was written, prices and argument unchanged.
How Alcaraz Went From 27 Cents To 42
On draw day the men's board was an argument about a wrist. Alcaraz had not played a singles match since April, and the crowd held him under 27 cents through draw week while Alexander Zverev, handed the top seed by Jannik Sinner's withdrawal, sat a few cents behind him.
Then the tournament started badly for everyone else at the top of the draw. Djokovic, the fourth seed, lost his opener to Mariano Navone in five sets. Arthur Fils, the 10th seed in Alcaraz's quarter, lost his to Stefanos Tsitsipas. Rafael Jodar, the 12th seed, lost on Wednesday to a lucky loser, and on Thursday morning Felix Auger-Aliassime, the third seed, went out to Karen Khachanov. Alcaraz beat Roman Safiullin and Jaime Faria and dropped one set doing it.
The crowd read all of that as one thing. Alcaraz closed at 27 cents on the eve of the tournament, then climbed through every session to a 42.5-cent midpoint by Thursday afternoon, where a full evening session left it. More than twice as many contracts have traded on him as on any other name. Zverev, who needed five sets to get past Lorenzo Sonego in the first round, drifted to 21.5, and Taylor Fritz is the only other man above 10 cents.
The women's board barely moved. Sabalenka, the two-time defending champion, has hardly left her draw-week price and sits at 23.5 after two easy rounds. Coco Gauff rose on her Cincinnati title and settled at 18.5, the same price before and after beating Paula Badosa on Thursday night. Iga Swiatek slid to 13.5 even after a straight-sets win, and Jessica Pegula edged up to 8.5. The top four are priced almost exactly where the seedings and the August results would put them. Only one women's contract has repriced against its own form, and it belongs to the 17th seed covered below.
The Men's Board: A Favorite The Panel Won't Pay 42 Cents For
Prices are the midpoint of Kalshi's best bid and ask at 10 p.m. ET on September 3. The panel column is the middle seat's number after a revision round, rescaled so each seat's board sums to 100 including a field bucket for any champion with no contract. The gap compares the panel to the market with Kalshi's overround stripped out. The panel sat on Thursday afternoon, so two men it priced, Alex de Minaur and Lorenzo Musetti, lost that night; their rows sit under the table with the panel's number kept, because a miss is part of the record.
| Player | Seed | Kalshi | AI blend | Gap |
|---|---|---|---|---|
| Carlos Alcaraz | No. 2 | 42.5¢ | 24.4% | -15.3 |
| Alexander Zverev | No. 1 | 21.5¢ | 11.4% | -8.7 |
| Taylor Fritz | No. 9 | 10.5¢ | 8.5% | -1.3 |
| Ben Shelton | No. 8 | 8.5¢ | 8.5% | +0.6 |
| Daniil Medvedev | No. 7 | 5.5¢ | 7.0% | +1.9 |
| Frances Tiafoe | No. 11 | 2.5¢ | 5.2% | +2.9 |
| Jakub Mensik | No. 17 | 2.5¢ | 1.5% | -0.8 |
| Tommy Paul | No. 20 | 1.5¢ | 2.4% | +1.0 |
| Learner Tien | No. 14 | 1.5¢ | 2.0% | +0.6 |
| Flavio Cobolli | No. 5 | 1.5¢ | 1.1% | -0.3 |
| Karen Khachanov | unseeded | 0.5¢ | 2.0% | +1.5 |
| Alex Michelsen | unseeded | 0.5¢ | 1.6% | +1.1 |
| Stefanos Tsitsipas | unseeded | 0.5¢ | 1.5% | +1.0 |
| Alexander Bublik | No. 15 | 0.5¢ | 1.5% | +1.0 |
| Francisco Cerundolo | No. 24 | 0.5¢ | 1.0% | +0.5 |
| Valentin Vacherot | No. 22 | 0.5¢ | 0.8% | +0.3 |
| The Field (Any Player With No Contract) | — | 0.0¢ implied | 10.0% | — |
Priced at zero by every seat, because they are out of the draw or never entered it: Andrey Rublev, Hubert Hurkacz, Jan-Lennard Struff, Cameron Norrie, Dino Prizmic, Jack Draper, Sebastian Korda, Holger Rune, Casper Ruud and Gabriel Diallo. Kalshi still quotes each at a 1-cent ask with no bid; Felix Auger-Aliassime's contract, in that group at the afternoon pull, has since been settled.
Priced by the panel on Thursday afternoon, beaten on Thursday night: Alex de Minaur, the sixth seed, 4.5% on the panel, lost to Botic van de Zandschulp; Lorenzo Musetti, the 13th seed, 2.2%, lost to Dane Sweeny. Both contracts now sit at a half-cent midpoint.
Strip the overround and the crowd makes Alcaraz a 39.7% champion. The middle seat says 24.4%, and the eight seats that scored the board ran from just under 20 to 28. Nobody on the panel doubts he is the favorite. What they will not do is price a man who had not played since April at nearly double the top seed after two wins over unseeded opponents, with Ben Shelton, who won the Toronto title in August, waiting in his projected quarterfinal.
Alcaraz stays the single favorite (two clean, increasingly dominant wins answer the wrist-layoff question) but capped near 22 because his Q4 QF likely means Shelton, who is playing the best tennis on the board (Toronto title, straight-setted Hurkacz). — Claude Sonnet
The Zverev gap runs the other way for a reason. The seats keep citing the same three results: a loss to Tallon Griekspoor in Toronto, a loss to Tommy Paul in Cincinnati, and a first round here in which he dropped two sets to Sonego. Where the panel's money went instead is the middle of the board, Daniil Medvedev and Frances Tiafoe above the market and both still alive, and the field: a 10% chance the champion is one of the men with no contract at all, a group that now includes Jiri Lehecka, Denis Shapovalov and van de Zandschulp.
The field row is where the seats argued hardest, from 7.3% to 22.2%. Part of that is a real disagreement about how much a draw without Sinner rewards the unseeded survivors. Part of it is one seat pricing a ghost: DeepSeek kept Djokovic in its field as "a major threat" after the results ledger had already shown him losing to Navone in the first round. The median carries that as one vote in eight.
The Women's Board: Sabalenka's Cleared Path, And A Price The Crowd Won't Sell
Same pull, same method. Four contracts belong to women who were already out when the panel sat and are priced at zero by every seat; two more the panel priced, Paula Badosa and Maria Sakkari, lost on Thursday night. All six sit under the table.
| Player | Seed | Kalshi | AI blend | Gap |
|---|---|---|---|---|
| Aryna Sabalenka | No. 1 | 23.5¢ | 17.0% | -4.3 |
| Coco Gauff | No. 4 | 18.5¢ | 13.5% | -3.2 |
| Iga Swiatek | No. 8 | 13.5¢ | 13.0% | +0.8 |
| Jessica Pegula | No. 3 | 8.5¢ | 9.0% | +1.3 |
| Elena Rybakina | No. 2 | 5.5¢ | 9.0% | +4.0 |
| Karolina Muchova | No. 7 | 5.5¢ | 4.5% | -0.5 |
| Mirra Andreeva | No. 5 | 5.5¢ | 4.0% | -1.0 |
| Amanda Anisimova | No. 10 | 4.5¢ | 3.8% | -0.3 |
| Naomi Osaka | No. 13 | 4.5¢ | 3.0% | -1.1 |
| Marta Kostyuk | No. 11 | 4.5¢ | 2.0% | -2.1 |
| Alexandra Eala | No. 17 | 4.5¢ | 0.5% | -3.6 |
| Linda Noskova | No. 6 | 2.5¢ | 2.5% | +0.2 |
| Elina Svitolina | No. 9 | 2.5¢ | 1.6% | -0.7 |
| Iva Jovic | No. 14 | 1.5¢ | 0.5% | -0.9 |
| Madison Keys | No. 22 | 1¢ | 1.5% | +0.6 |
| Jasmine Paolini | No. 19 | 0.5¢ | 1.0% | +0.5 |
| Emma Navarro | No. 26 | 0.5¢ | 0.8% | +0.3 |
| Qinwen Zheng | unseeded | 0.5¢ | 0.2% | -0.3 |
| The Field (Any Player With No Contract) | — | 0.0¢ implied | 12.2% | — |
Priced at zero by every seat: Barbora Krejcikova, Jelena Ostapenko, Maja Chwalinska and Victoria Mboko.
Priced by the panel on Thursday afternoon, beaten on Thursday night: Paula Badosa, 0.5% on the panel, lost to Coco Gauff; Maria Sakkari, the 32nd seed, 0.4%, lost to Yuliia Starodubtseva. Both contracts sit at a half-cent midpoint.
The women's gaps are smaller everywhere, and the shape is different: the panel is not fading the favorite so much as redistributing among the top five. It takes about four points off Sabalenka and three off Gauff and gives them to Rybakina and Pegula, and the reason is the draw. Sabalenka's quarter has already lost two of its seeds, and her semifinal comes from the Pegula and Muchova quarter. Gauff won Cincinnati and drew the hardest road on the board: a quarter shared with Mirra Andreeva and Amanda Anisimova, then whoever survives the Swiatek, Rybakina and Osaka quarter.
Rybakina is the widest women's gap in the panel's favor, 9.0% against 5.5 cents for the second seed. The crowd's reason is a fitness event: she retired hurt against Swiatek in the Cincinnati quarterfinal, a week after losing the Toronto final to her. The panel's reason for not selling her that low is that she is the Australian Open champion, ranked second in the world, and won her opener here in straight sets. The Pegula row is the quieter version: a Cincinnati finalist who beat Swiatek there, priced at 8.5 cents in a quarter whose only other top-eight seed is Muchova.
Then there is the row that repriced against its own form. Alexandra Eala, the 17th seed, sits at 4.5 cents, level with Osaka and Anisimova, on more traded volume than any other women's contract, Gauff included. The panel's middle number for her is 0.5%, and not one seat gave her more than 0.8. Her record here is a first-round win over a qualifier and a second-round win over Oleksandra Oliynykova, and her quarter contains Gauff. Her own page covers why the crowd keeps buying at a price the results have not earned.
The women's field row is the one the seats agree on most. Two of the names they put in it, Belinda Bencic and Sara Bejlek, had already lost in the first round, which the card could not tell them because it tracks contract-holders only. Two more were alive going into the third round: Ekaterina Alexandrova, who beat Sabalenka in August, and Diana Shnaider, who beat Pegula.
What The Panel Said About Friday's Third Round
The panel also priced the 19 third-round match contracts Kalshi had listed on Thursday afternoon, all of them played on Friday, after this pull. Eleven landed within five points of the market, which is what you would expect from a panel reading the same rankings the crowd does. The eight that did not all leaned the same way: the panel shaded the favorite down.
The two widest gaps were the same argument twice. Kalshi made Alex Michelsen a 59.5-cent favorite over Daniel Merida; the panel made him a 43% underdog, because Merida had beaten him on the same surface in Toronto in August and then beat Andrey Rublev here. Marta Kostyuk was priced at 74.5 cents against Alexandrova; the panel had her at 60, on the strength of Alexandrova's win over Sabalenka a month earlier. Both matches have been played and both calls are on the ledger. This page carries the grades when the boards are re-pulled.
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Why Every Gap Points The Same Way
Read the gap columns top to bottom and the same thing shows up on both boards: the crowd pays extra for the name at the top of the list, and the panel does not. On the men's board the panel sits 24 points below the market on Alcaraz and Zverev combined and above it on most of the rest. On the women's board the discount on Sabalenka and Gauff is 7.5 points, and the money goes to Rybakina and Pegula.
That has two readings. Either a crowd trading on names pays a premium for the player it has heard of, which is what the seats' own reasoning keeps saying, or nine models that cannot see a price underweight the thing the price knows: how a two-time champion here looks on a court against a man ranked outside the top 100. The last time this panel priced the men's board, before a ball was hit, it had Alcaraz at 14.2% against a 26.5-cent market. By the September 3 pull it had him at 24.4 against 42.5. Both numbers moved the same way; the market's moved half again as far.
How The Panel Priced It
Nine AI models received the same data card and no prices: the full draw, every contract-holder's results from the hard-court lead-in events and every completed US Open match to the minute the card was built, current rankings, and biography facts. Each seat priced the men's board, the women's board and the third-round matches, then read the other seats' anonymized reasoning and was allowed to revise. The blend is the middle seat's number, not the average, so one outlier cannot drag the headline figure. Eight of nine returned a usable men's board; all nine returned the women's. Every number was written to the public grading ledger as it was made, and each seat's record lands on the full graded scoreboard when the finals settle, win or lose.
When This Gets Graded
Kalshi's title markets settled with the finals: Rybakina's contract paid on Saturday, September 12, and Zverev's on Sunday, September 13; every other name on both boards settled No. The graded table is at the top of the page. A player who withdraws sees their own contract settle No. Prices on this page are from one pull at 10 p.m. ET on September 3; the panel priced the boards that afternoon, before the evening session, and its numbers are shown as they were made. The boards get re-pulled and re-scored as the tournament moves, and every call above, on the titles and on the third-round matches, lands on the public scoreboard whether it wins or loses.
Models are frequently wrong, and the market price reflects real traders' money.*
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