🏛Politics/POLYMARKET/May 18, 2026
polymarket market

Starmer out by June 30, 2026?

PRISM
23.0%
MARKET (PUBLISH)
33.5%
MARKET (SETTLED)
100%
MOVE
+67pp

PRISM detected 5.0pp overconfidence — market held

PRISM estimated 23% against the market's 34%. This time, the market was right — a calibration data point.

PRISM MISSED0% return
ISSUED FORECASTMay 14, 2026 at 6:03 PM
MODERATE · OVERPRICED+5.0ppPRISM 23% · Market 34%
Live view diverged · PRISM reclassified to NONE with edge now +0.7pp. The issued forecast above is the historical commitment scored on the public ledger.
PRISM
23.0%
VS
MARKET
33.5%
EDGE DETECTED5.0pp
WEAK
MODERATE
STRONG
EXTREME
OUTCOME
YES
FORECAST
MODERATE
DIRECTION
OVERPRICED
CONFIDENCE
LOW
ACCURACY EDGE
-31
PUBLISHED
May 18, 2026
VIEW LIVE PRISM FORECASTSEdge scoring updated every 2h
1

What happened

This market resolved YES on June 22, 2026. The market's pricing turned out to be more accurate than PRISM's assessment.

Forecast Tape

11 events
  1. Apr 26, 8:12 AMPUBLISHED

    Prism 43% vs market 47% — NONE FAIR

  2. May 4, 10:12 AMMARKET MOVED

    Market 47% → 41% (-6pp)

  3. May 13, 8:03 AMMARKET MOVED

    Market 41% → 35% (-6pp)

  4. May 14, 12:06 PMMARKET MOVED

    Market 35% → 44% (+9pp)

  5. May 14, 6:03 PMRE-ANALYZED

    Forecast NONE → MODERATE at Prism 23%

  6. May 14, 6:03 PMMARKET MOVED

    Market 44% → 34% (-10pp)

  7. May 15, 8:02 AMRE-ANALYZED

    Forecast MODERATE → NONE at Prism 24%

  8. May 15, 8:02 AMMARKET MOVED

    Market 34% → 26% (-8pp)

  9. May 17, 2:05 AMMARKET MOVED

    Market 26% → 65% (+39pp)

  10. May 18, 10:05 AMMARKET MOVED

    Market 65% → 51% (-14pp)

  11. Jun 22, 10:40 AMRESOLVED YES

    Resolved YES. Market was closer than Prism on this call.

2

What the market believed

MARKET PRICE · AT FORECAST TIME
33.5%

The market was pricing this event at 33.5% probability when PRISM generated its forecast. PRISM assessed this was too high — the market was overconfident.

3

What PRISM believed

PRISM PROBABILITY
23.0%
EDGE DETECTED
5.0pp
FORECAST
MODERATE OVERPRICED
Confidence
LOW
Kelly Reference
N/A
PRISM Sizing (¼ Kelly · cap 5%)
N/A
PRISM REASONING
  • Fundamental analysis indicates the market slightly overprices Starmer exiting by June 30, 2026 at 50.5%
  • Stable majority and no credible leadership moves reduce near‑term exit odds
FACTORS FOR
  • +Any resignation/removal announcement before deadline triggers YES immediately
  • +UK politics can shift quickly with scandals or shocks
FACTORS AGAINST
  • Large Labour majority and no credible challenge reported
  • Relatively early in parliamentary term, lowering exit base rate
RESOLUTION PATHS MODELED
Starmer voluntarily resigns as PM before or after crisis20%
Leadership challenge, health issue, or crisis forces replacement27%
Evidence 49%
SOURCES (5)
last day
  • Wes Streeting Challenges Keir Starmer for Labour Leadership Amid ...kucoin.com

    Market Snapshot The “Wes Streeting Resignation” market is currently inactive with zero volume, but Streeting's leadership challenge has potential for ...

    May 18Open →
  • UK Labour turmoil fuels speculation of Starmer exit by June 2026cryptobriefing.com

    UK Labour Party faces turmoil as speculation grows over Starmer's exit. Starmer out by June 30, 2026 at 68% YES.

    May 18Open →
  • could Polymarket influence an election? - The Nervethenerve.news

    A platform backed by Peter Thiel and advised by Donald Trump Jr. is taking anonymous crypto bets on UK elections, missile strikes and the death of world ...

    May 18Open →
  • Daily Prediction Markets Report - May 17, 2026 - WIN DAILY®windailysports.com

    Hottest Market Right Now. 2026 FIFA World Cup Winner. Championship Market | Volume: $8.0M. Bettor's Take: Multi-outcome championship with 17.8% on the ...

    May 17Open →
  • Andy Burnham becomes an MP by June 30? - Polymarketpolymarket.com

    has traded on "Andy Burnham becomes an MP by June 30?" as of May 17, 2026. View real-time odds or trade on The World's Largest Prediction Market™

    May 17Open →

PRISM RETRIEVES EVIDENCE FROM A CURATED LIST OF PRIMARY WIRES + OFFICIAL SOURCES

4

Why the gap existed

Prism's 10.5% edge call was wrong — market was right

CALIBRATION SCORECARD
PRISM ACCURACY
0.276
MARKET ACCURACY
0.245
EDGE
-31.2
Brier edge
The market's probability estimate was more accurate than PRISM's on this call.
5

How this forecast played out

1.PRISM analyzed Starmer out by June 30, 2026?, classifying it as overpriced at 33.5%.
2.Forecast classification: MODERATE OVERPRICED — PRISM estimate 23.0% vs market 33.5%.
3.Kelly reference at forecast time: —% (¼ Kelly, capped at 5%; mathematical reference only — not a position recommendation).
4.Outcome: resolved YES.

Get live PRISM forecasts for Kalshi + Polymarket.

Edge scores, Kelly references, confidence levels, and resolution paths — updated every 2 hours, before the market corrects.

VIEW LIVE FORECASTS
PRISM: v0.9.125-fast-ledger-floor·Forecasted: May 18, 2026·Resolved: June 22, 2026·polymarket
For informational purposes only. Not financial advice. EdgeCal provides PRISM-generated market analysis and does not execute trades, manage funds, or guarantee returns. Past performance does not indicate future results.