Will there be a Supreme Court vacancy in 2026?
Liquidity-weighted aggregate sits at 20% across 27 contracts. Kalshi at 19%, Polymarket at 22% — a 3pp cross-venue gap.
Implied probability
Kalshi
19%
12 contracts
Polymarket
22%
15 contracts
Cross-venue gap
3pp
modest gap
24h move
—
no pin
24h volume
$106K
27 contracts
Closes
Dec 31, 2026
150 days
30-day trend
Cross-venue edge
Kalshi 19¢ · Polymarket 22¢ · 3pp spread
Buy on Kalshi (19¢, 12 contracts) and sell on Polymarket (22¢) — assuming both contracts settle on the same outcome.
Bracket families
6 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 19% of their title tokens — “Who will the Trump admin next nominate as SCOTUS Justice” vs “What will the Supreme Court look like at the end of Trump's term”. The headline aggregate weights both, so the number on this page is meaningful only if the clusters resolve to the same question.
Cluster 1
Who will the Trump admin next nominate as SCOTUS Justice
Who will the Trump admin next nominate as SCOTUS Justice?: Andrew Oldham
0x9f042d…467b
Who will the Trump admin next nominate as SCOTUS Justice?: Aileen Cannon
0x5adf29…d1be
Who will the Trump admin next nominate as SCOTUS Justice?: James Ho
0xe04896…665f
Who will the Trump admin next nominate as SCOTUS Justice?: Amul Thapar
0xb251e2…36d9
Who will the Trump admin next nominate as SCOTUS Justice?: Gregory Katsas
0x877145…4a04
Who will the Trump admin next nominate as SCOTUS Justice?: Mike Lee
0xdb70b0…b203
Cluster 2
What will the Supreme Court look like at the end of Trump's term
What will the Supreme Court look like at the end of Trump's term?
KXSCOTUSPOWER-29-29JAN20-R0-0
What will the Supreme Court look like at the end of Trump's term?
KXSCOTUSPOWER-29-29JAN20-R6-3
What will the Supreme Court look like at the end of Trump's term?
KXSCOTUSPOWER-29-29JAN20-R7-2
What will the Supreme Court look like at the end of Trump's term?
KXSCOTUSPOWER-29-29JAN20-R8-1
What will the Supreme Court look like at the end of Trump's term?
KXSCOTUSPOWER-29-29JAN20-R9-0
Cluster 3
Who will win the 2026
Who will win the 2026 Kansas Elections for Supreme Court Justices Amendment?
KXKSAMEND-26-YES
Who will win the 2026 Michigan Supreme Court election?
KXMISC-26-2R
Who will win the 2026 Michigan Supreme Court election?
KXMISC-26-1DR
Who will win the 2026 Michigan Supreme Court election?
KXMISC-26-2D
Cluster 4
Will Clarence Thomas announce their departure as Supreme Court justice before J
Will Clarence Thomas announce their departure as Supreme Court justice before Jan 1, 2027?
KXTHOMASANNOUNCERETIRE-26JUL-27JAN01
Will Clarence Thomas announce their departure as Supreme Court justice before Jul 1, 2027?
KXTHOMASANNOUNCERETIRE-26JUL-27JUL01
Will Clarence Thomas announce their departure as Supreme Court justice before Jan 1, 2028?
KXTHOMASANNOUNCERETIRE-26JUL-28JAN01
Cluster 5
What cases will the Supreme Court agree to hear before Jan 2027
What cases will the Supreme Court agree to hear before Jan 2027?
KXTRUMPTARIFFHEAR-27JAN-X
Cluster 6
Supreme Court vacancy in 2026
Supreme Court vacancy in 2026?
0x4bfb8b…6e3b
Analysis
Market evidence is not negligible: kalshi "What cases will the Supreme Court agree to hear before Jan 2027?" 22¢; polymarket "Supreme Court vacancy in 2026?" 26¢; kalshi "Will Clarence Thomas announce their departure as Supreme Court justice before Jan 1, 2027?" 9¢. Resolution windows can differ across venues, so treat the odds as contract-specific rather than one combined probability.
- ›Clarence Thomas retirement probability
- ›Long-term vacancy outlook
- ›Supreme Court stability
What moved the line
- Aug 2Will Clarence Thomas announce their departure as Supreme Court justice before Jan 1, 2028?↓11pp40→29¢ · Kalshi
- Aug 1Will Clarence Thomas announce their departure as Supreme Court justice before Jul 1, 2027?↓7pp25→18¢ · Kalshi
- Aug 2Will Clarence Thomas announce their departure as Supreme Court justice before Jul 1, 2027?↓6pp18→12¢ · Kalshi
- Aug 3Will Clarence Thomas announce their departure as Supreme Court justice before Jan 1, 2027?↓4pp8→4¢ · Kalshi
- Aug 6What cases will the Supreme Court agree to hear before Jan 2027?↓3pp17→14¢ · Kalshi
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These markets stopped trading. Last odds and any captured outcome are shown above — full settlement detail lives at the venue.
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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.
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