50% — ATP Tennis Matches
Kalshi 50% · 4 contracts · $780K volume · medium confidence
Updated 2026-06-08 04:07:33 UTC

Why this matters:
This probability reflects market expectations that a player other than Carlos Alcaraz or Jannik Sinner will win at least one ATP Grand Slam title in 2026. Currently priced at 57%, it suggests the market views these two as favorites to dominate the four major tournaments but still expects meaningful competition from the rest of the field. The level is driven by Alcaraz and Sinner's recent dominance—Alcaraz won multiple majors in 2024 and Sinner won the Australian Open in 2025—against historical precedent where Grand Slams are distributed more broadly. The probability will shift based on tournament outcomes beginning with the French Open in May 2026, the first major of the year. Performance by Novak Djokovic, Rafael Nadal, Jannik Sinner's form, injuries, and seeding will all influence which other players have realistic paths to a major title.

Key factors:
- Alcaraz and Sinner have won four of the last five Grand Slam tournaments combined (2024-2025), establishing them as the current favorites
- The French Open begins May 2026, the first major tournament that will test whether challengers can break through or whether one of the two favorites wins again
- Historical Grand Slam distribution shows that across 2015-2019, five different men won the four major tournaments each year, suggesting other winners remain possible
- Djokovic's age (38-39 in 2026) and recent injury history may affect his competitiveness versus mid-career alternatives like Medvedev, Tsitsipas, or emerging players
- Contract volume of $870 over 24 hours is relatively modest, indicating limited market conviction and potential for significant probability shifts based on new information

Contracts:
- Will Jakub Mensik win the Mensik vs Zverev: Semifinal match?: Jakub Mensik — 22¢ Kalshi $395K (weight 51%)
- Will Alexander Zverev win the Mensik vs Zverev: Semifinal match?: Alexander Zverev — 77¢ Kalshi $181K (weight 23%)
- Will Flavio Cobolli win the Arnaldi vs Cobolli: Semifinal match?: Flavio Cobolli — 68¢ Kalshi $110K (weight 14%)
- Will Matteo Arnaldi win the Arnaldi vs Cobolli: Semifinal match?: Matteo Arnaldi — 31¢ Kalshi $95K (weight 12%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-06-05T19:20:12.252Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "50% per prediction markets (SimpleFunctions, June 2026)"
Canonical: https://simplefunctions.dev/answer/atp-tennis
Full data: https://simplefunctions.dev/api/public/query?q=ATP%20Tennis%20Matches
Provider: SimpleFunctions — https://simplefunctions.dev