Massachusetts Democratic Senate Primary Winner
Leader sits at 70% across 2 bound outcomes, runner-up at 27%. This is a winner-take-all market — the headline is the leader’s price, not an arithmetic mean.
Leader probability
Ed Markey
Outcomes
2
winner-take-all
Runner-up
27¢
Seth Moulton
Spread
43pp
contested
24h volume
$79
thin orderbook
Closes
Sep 1, 2026
115 days
Venue
Polymarket
2 bound
30-day trend
Bracket family
How the bracket ladder is priced.
Each row is one outcome on the venue. Sorted by 24h volume — the heaviest book is at the top.
Cluster 1
Massachusetts Democratic Senate Primary Winner
Analysis
This probability reflects the current market assessment of which candidate will win the Massachusetts Democratic Senate primary. At 82%, the leading candidate is viewed as the clear favorite, though the 15% probability for the runner-up indicates meaningful uncertainty remains. The primary outcome will depend on voter preferences across the state's urban, suburban, and regional demographics, fundraising totals and spending patterns, and earned media coverage leading up to the primary election. Turnout levels among key Democratic voting blocs—including younger voters, progressive activists, and communities of color—will likely prove decisive. The election date itself will serve as the definitive resolution point, eliminating speculation and determining the actual winner. Until then, shifts in polling data, endorsement announcements, or campaign spending could move these probabilities.
- ›Current polling gaps between the top two candidates and whether any recent surveys show movement toward or away from the 82% frontrunner
- ›Endorsement patterns from Massachusetts Democratic establishment figures, labor unions, and progressive organizations that can mobilize specific voter blocs
- ›Campaign fundraising and spending reports filed with state election authorities, indicating resource disparities in media and field operations
- ›Turnout modeling and demographic composition of early voting and absentee ballots compared to historical primary patterns
- ›Scheduled primary election date and whether any major events or developments occur in the final weeks that reshape candidate viability or voter perception
What moved the line
- May 7Ed Markey↓15pp83→68¢ · Polymarket
- May 7Seth Moulton↑9pp19→28¢ · Polymarket
- May 6Seth Moulton↑4pp15→19¢ · Polymarket
Recently closed in election 2026
- Will a reconciliation bill passed the Senate before May 20, 2026last 94% · 1d
- Will John Fetterman leave the Democratic party before Jun 1, 2026last 16% · 1d
- Will the Democratic National Committee release a comprehensive post-election report of the 2024 election before Aug 1, 2026last 67% · 1d
- Balance of Power: 2026 Midterms: D Senate, R Houselast 3% · 1d
- What will any participating candidate say during California Governor Debatenolast 55% · 1d
These markets stopped trading. Last odds and any captured outcome are shown above — full settlement detail lives at the venue.
Lateral coverage
Thin contract — here's where the deeper coverage is.
This page aggregates 2 contracts (70% headline). At low contract count, the price reflects two participants’ opinions, not a market consensus. The links below are heavier related questions where the orderbook signal is real.
Thicker comparable contracts
In election 2026
Related reading
California Billionaire Wealth Tax Ballot Measure Surges +23¢ — Now 93¢ to Appear
The Polymarket contract for whether a one-time billionaire tax appears on the California 2026 ballot jumped an extraordinary +23¢ to 93¢ today, while the separate 'passes' contract jumped +10¢ to 48¢. This suggests the measure has cleared a major legal or signature-gathering threshold.
2026 Midterms: Democrats 85% to Flip House, Senate a Toss-Up
Prediction markets price Democrats as 85% favorites to flip the House while the Senate races at a coin-flip, with a full Democratic sweep now the single most likely outcome at 50%.
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: 4 min ago.