Will Frances Tiafoe win the 2026 Men's US Open?

Crossbook compares what two exchanges, Polymarket and Kalshi, charge for the same event, and publishes a permanent scored record of its own forecasts under published rules.

Settlement equivalence unverified. No eligible price gap is available.

SettledContract settles 13 Sept 2026Last checked 12 Sept 2026, 03:05 UTC

Bid/ask midpoint · retrieved 2026-09-12T03:05:26.752Z. Venue quote-update time is unavailable. Readings can be asynchronous.

2.1%bid 1.4% / ask 2.8%24h volume $122K · liquidity $83Kas of 12 Sept, 03:05 UTC · not refreshed recentlyView on Polymarket

Bid/ask midpoint · retrieved 2026-09-12T03:10:26.930Z. Venue quote-update time is unavailable. Readings can be asynchronous.

no two-sided marketnobody is quoting both sides, so there is no price to show24h volume $325K · liquidity –as of 12 Sept, 03:10 UTC · not refreshed recentlyView this market's series on Kalshi

How each venue defines this

Each exchange's own settlement text, quoted as written. Where they differ, the difference is usually why the prices do.

Settles Sep 13, 26

The 2026 U.S. Open tennis tournament is scheduled for August 23 - September 13, 2026. This market will resolve to the player that wins the 2026 U.S. Open Men’s Singles Tournament. If at any point it becomes impossible for a listed player to win the 2026 U.S. Open Men’s Singles Tournament per the rules of the tournament, the corresponding market will resolve to “No”. If the 2026 U.S. Open Men’s Singles Tournament is cancelled, postponed after October 31, 2026, or there is otherwise no winner declared within that timeframe, this market will resolve to “Other”. The primary resolution source w…

Settles Sep 14, 26

If Frances Tiafoe wins the 2026 US Open Men's Singles professional tennis tournament, then the market resolves to Yes.

Settlement equivalence unverified

A person confirmed these two markets ask the same question. Their settlement documents have not been compared, so treat the price difference as unverified rather than as a like for like gap.

Confirmed as the same question: Will Frances Tiafoe win the 2026 Men's US Open?

Price, last 60 days

Crossbook forecast

14.0%against a market price of 5.1% at the timeNO
Logged 9 Sept 2026, 03:43 UTC · Brier 0.0196
- Tiafoe is confirmed into the 2026 US Open semifinals after beating Michelsen in the quarterfinal, so he is two wins from the title — the reference class narrows to four remaining players, putting a naive ceiling near 25%.
- Tiafoe's career record at Slams (no titles, one prior US Open semifinal in 2022, one semifinal in 2024) suggests he is typically not the best player remaining in a major final four; late rounds at recent Slams have been dominated by Sinner and Alcaraz, and if either remains in the draw Tiafoe would be an underdog in both remaining matches.
- His wins over Vacherot and Michelsen came against non-elite opposition, so they confirm form but don't demonstrate he has beaten a top-5-caliber opponent this tournament — narrative momentum is weaker signal than the strength-of-opposition gap.
- Time-decay is irrelevant here in the usual sense: the event is essentially live (closes 2026-09-13, the final), so probability should track his true two-match win likelihood, roughly 0.55 x 0.30-0.40 if facing a top seed in the final, landing near 13-16%.
What would change it: Learning the semifinal draw — specifically if both Sinner and Alcaraz have been eliminated or Tiafoe's semifinal opponent is another non-top-10 player — would raise my estimate toward 30%+; conversely a semifinal pairing against Sinner or Alcaraz would push it toward 8-10%.
Settlement sourcet-0183

Settlement equivalence unverified. The venue readings below are not ranked as a comparable price gap.

Volume over the last 24 hours is heavy, at about $325,016 on the busier venue. At least one side of this market has no real two sided book, which means the quoted price is closer to a placeholder than to a traded level.

This market has settled. The page is kept as a record of what both venues said while the question was open, and of what Crossbook called.

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