SimpleFunctions
20 contractsKalshirefreshed 40 min agoCloses Dec 31, 2026 · 241d

Who will win a Calendar Grand Slam in 2026

Liquidity-weighted aggregate sits at 27% across 20 Kalshi contracts.

Implied probability

27%
0%50%100%

Kalshi

27%

20 contracts

Polymarket

not bound

Cross-venue gap

single venue

24h move

no pin

24h volume

$6K

20 contracts

Closes

Dec 31, 2026

241 days

30-day trend

0%50%100%-30d-3w-2w-1wtodayAggregate: 37% (26 days, 26 points)Aggregate: 37% on 2026-05-03
Aggregate of 20 contracts · 26d

Bracket families

17 clusters across 20 contracts.

These contracts were grouped by title similarity. The headline aggregate combines all clusters; verify the cluster you actually need before quoting a number.

Heads-up — heterogeneous clusters

The top two clusters share only 8% of their title tokens — “How many Grand Slams” vs “Will Scottie Scheffler win the grand slam before 2028”. The headline aggregate weights both, so the number on this page is meaningful only if the clusters resolve to the same question.

Cluster 1

How many Grand Slams

4 contracts$673

Cluster 2

Will Scottie Scheffler win the grand slam before 2028

1 contract$2K

Cluster 3

Will Aryna Sabalenka win a Tennis Grand Slam in 2026

1 contract$1K

Cluster 4

Will any man other than Carlos Alcaraz and Jannik Sinner win any ATP Tennis Grand Slam in 2026

1 contract$655

Cluster 5

Will Novak Djokovic win a Tennis Grand Slam in 2026

1 contract$463

Cluster 6

What will the announcers say during Blue Jays vs Twins Professional Baseball Game

1 contract$245

Cluster 7

Will Amanda Anisimova win a Tennis Grand Slam in 2026

1 contract$197

Cluster 8

Will Alexander Zverev win a Tennis Grand Slam in 2026

1 contract$65

Cluster 9

Will Jannik Sinner win a Tennis Grand Slam in 2026

1 contract$12

Cluster 10

Will Mirra Andreeva win a Tennis Grand Slam in 2026

1 contract$0

Cluster 11

Will Coco Gauff win a Tennis Grand Slam in 2026

1 contract$0

Cluster 12

Will Daniil Medvedev win a Tennis Grand Slam in 2026

1 contract$0

Cluster 13

Will Karen Khachanov win a Tennis Grand Slam in 2026

1 contract$0

Cluster 14

Will Frances Tiafoe win a Tennis Grand Slam in 2026

1 contract$0

Cluster 15

Will Lorenzo Musetti win a Tennis Grand Slam in 2026

1 contract$0

Cluster 16

Will Jack Draper win a Tennis Grand Slam in 2026

1 contract$0

Cluster 17

Will Casper Ruud win a Tennis Grand Slam in 2026

1 contract$0

What moved the line

  • May 1Grand Slam17pp421¢ · Kalshi
  • Apr 263+ Grand Slam wins8pp1725¢ · Kalshi
  • May 2Grand Slam8pp2129¢ · Kalshi
  • Apr 282+ Grand Slam wins6pp4135¢ · Kalshi
  • Apr 302+ Grand Slam wins4pp3632¢ · Kalshi

Recently closed in general

These markets stopped trading. Last odds and any captured outcome are shown above — full settlement detail lives at the venue.

More like this

Adjacent prediction questions.

How we compute these odds

SimpleFunctions aggregates live prediction-market contracts from Kalshi and Polymarket. Each slug groups contracts that resolve on the same underlying event, identified by venue event_id.

For binary slugs, the headline probability is the liquidity-weighted mid-price across all bound contracts. For multi-outcome slugs (e.g. elections with 3+ candidates), the headline is the leader’s price; we never arithmetically average disjoint outcomes — that would produce a number with no real-world meaning.

Snapshots refresh every 5 minutes during market hours; daily aggregates are computed at 04:00 UTC. The 30-day sparkline is drawn from per-ticker daily means stored in market_indicator_daily; 24h delta and movement events are derived from the same source.

Last updated on this page: 40 min ago.