Polymarket's "Will Elena Rybakina win the 2026 Women's US Open?" contract has climbed from 18.4c to 26.5c since Wednesday, after Rybakina beat Zheng Qinwen in the quarterfinals to become the WTA's world No. 1 for the first time in her career. The win also completed the tournament's first all-top-four-seed women's semifinal since 1975 - only the second time in the Open Era - and the first at any Grand Slam since Wimbledon 2009. Rybakina plays the No. 4 seed, Coco Gauff, in Thursday night's semifinal; Aryna Sabalenka, the No. 1 seed and outright favorite at 36c, plays Jessica Pegula in the other. The event has traded $477K over the past 24 hours on $247K of liquidity. Numbers below are from Gamma and the CLOB, fetched 2026-09-10 11:35 UTC.
01The rankingA first career No. 1, and a once-in-51-years semifinal
Rybakina, the 2022 Wimbledon champion, had never finished a week ranked No. 1 before Wednesday. She got there by reaching her first US Open semifinal, beating Zheng Qinwen in the quarterfinal - Zheng, seeded well outside the tournament's top group, had herself upset two-time major champion Iga Swiatek in the fourth round Monday. Swiatek's own title contract, which had held a steady 14.5c through the weekend, collapsed to 0.05c the moment that match ended. Rybakina's win over Zheng two rounds later did the same to Zheng's contract while sending her own from 18.4c to a 25.65c high within three hours - the move that put her ahead of Aryna Sabalenka in the live rankings race regardless of how the rest of the tournament goes.
Sabalenka, who won the last two US Open titles and is chasing a third straight, ceded the No. 1 ranking this week but remains the market's outright favorite. She reached Thursday's semifinal by getting past Linda Noskova in her own quarterfinal. Gauff had the closer call: she faced match points against 18-year-old Mirra Andreeva on Wednesday evening before saving them and winning, a swing that took her own title contract from 20.9c down to a 12.5c low and back up to a 27.25c high within about two hours. Jessica Pegula, the tournament's No. 3 seed, beat Emma Navarro to round out the final four. The result: for the first time since 1975, and the first time at any Grand Slam since the 2009 Wimbledon Championships, the US Open women's draw enters the semifinals with its top four seeds still standing.
02The chartTwo contracts, two different kinds of rally
Rybakina's line shows one contract climbing in two clean steps: a quiet 6.65c through most of the weekend, a jump to 20.3c when she reached the quarterfinals late Monday, a second quiet stretch in the high teens, then Wednesday's jump to a 25.65c high on the Zheng win. Gauff's line shows the opposite shape - a gradual drift in the low 20s all week, then a sharp V on Wednesday evening as she went down match points and pulled the match back before it closed. Both contracts now sit within two points of each other heading into a semifinal that is a rematch: Rybakina beat Gauff the last time they met, making Thursday their second meeting in three tournaments.
03What's leftSabalenka still the favorite, tonight decides who's next
2026 WOMEN'S US OPEN YES 24H
Sabalenka 36.0c -0.5c
Rybakina 26.5c +7.6c
Gauff 25.0c +4.0c
Pegula 13.2c -0.8c
Sabalenka and Pegula meet for the 14th time on tour, and Sabalenka's order book shows the field still leans her way: about 330 shares bid at 36c against roughly 2,540 offered at 38c, a 2c spread. Rybakina's book is tighter - about 100 shares bid at 25.5c against 1,700 offered at 26.5c, a 1c spread - while Gauff's sits a point behind hers at a 23.9c/25.1c touch. The four contracts add up to 100.7c, in line with the modest overround a liquid multi-outcome book like this one typically carries. Both semifinals are scheduled for the Thursday night session on Arthur Ashe Stadium; whichever winners emerge will meet in Saturday's final, the last placement left on the ladder.
04Following it liveWatching a ladder reshuffle in real time
A dozens-of-outcomes title market like this one reprices in bursts - long stretches of near-silence between matches, then a single break point or final game moving every contract on the board at once, the way Gauff's did Wednesday night. polymarket-tui puts every outcome in an event on one screen with its own price and 24h change, so a moment like this shows up as a ladder that visibly flipped order rather than one number you have to already know to go looking for.
$ uv tool install polymarket-tui
$ polymarket-tui
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