🏛Politics/POLYMARKET/May 19, 2026
polymarket market

Will Thomas Massie be the Republican nominee for KY-04?

PRISM
41.9%
MARKET (PUBLISH)
36.5%
MARKET (SETTLED)
0%
MOVE
-37pp

PRISM detected 5.4pp mispricing — market held

PRISM estimated 42% against the market's 37%. This time, the market was right — a calibration data point.

PRISM MISSED-100% return
ISSUED FORECASTMay 19, 2026 at 10:06 PM
MODERATE · UNDERPRICED+5.4ppPRISM 42% · Market 37%
Live view diverged · PRISM reclassified to MODERATE with edge now +5.4pp. The issued forecast above is the historical commitment scored on the public ledger.
PRISM
41.9%
VS
MARKET
36.5%
EDGE DETECTED5.4pp
WEAK
MODERATE
STRONG
EXTREME
OUTCOME
NO
FORECAST
MODERATE
DIRECTION
UNDERPRICED
CONFIDENCE
MEDIUM
ACCURACY EDGE
-42
PUBLISHED
May 19, 2026
VIEW LIVE PRISM FORECASTSEdge scoring updated every 2h
1

What happened

This market resolved NO on May 20, 2026. The market's pricing turned out to be more accurate than PRISM's assessment.

Forecast Tape

12 events
  1. May 2, 6:09 AMPUBLISHED

    Prism 77% vs market 77% — NONE FAIR

  2. May 8, 8:05 PMMARKET MOVED

    Market 77% → 71% (-6pp)

  3. May 13, 2:08 PMMARKET MOVED

    Market 71% → 46% (-25pp)

  4. May 13, 8:09 PMRE-ANALYZED

    Prism 61% — edge +0.1pp

  5. May 13, 8:09 PMMARKET MOVED

    Market 46% → 56% (+11pp)

  6. May 14, 8:09 AMMARKET MOVED

    Market 56% → 66% (+10pp)

  7. May 17, 6:02 AMMARKET MOVED

    Market 66% → 49% (-18pp)

  8. May 18, 6:09 PMMARKET MOVED

    Market 49% → 38% (-11pp)

  9. May 19, 2:05 PMMARKET MOVED

    Market 38% → 46% (+8pp)

  10. May 19, 10:06 PMRE-ANALYZED

    Forecast NONE → MODERATE at Prism 42%

  11. May 19, 10:06 PMMARKET MOVED

    Market 46% → 37% (-9pp)

  12. May 20, 3:12 AMRESOLVED NO

    Resolved NO. Market was closer than Prism on this call.

2

What the market believed

MARKET PRICE · AT FORECAST TIME
36.5%

The market was pricing this event at 36.5% probability when PRISM generated its forecast. PRISM assessed this was too low — the market was underpricing the probability.

3

What PRISM believed

PRISM PROBABILITY
41.9%
EDGE DETECTED
5.4pp
FORECAST
MODERATE UNDERPRICED
Confidence
MEDIUM
Kelly Reference
N/A
PRISM Sizing (¼ Kelly · cap 5%)
N/A
PRISM REASONING
  • Thomas Massie appears modestly undervalued given incumbency advantages in House primaries despite a Trump-backed challenger
  • The key trade point is that only winning the primary nomination matters for resolution
FACTORS FOR
  • +Incumbent representatives historically win renomination at very high rates
  • +Market may overreact to single Trump endorsement in a localized race
FACTORS AGAINST
  • Race described by CBS News as a tossup
  • Trump endorsement and heavy spending increase upset risk
RESOLUTION PATHS MODELED
Massie defeats Gallrein and any others outright in primary34%
Massie prevails following close or delayed primary result5%
Evidence 52%
SOURCES (6)
last day
  • Full interview: GOP Rep. Thomas Massie on his primary ...youtube.com

    Republican Rep. Thomas Massie is bearing the brunt of the White House in his primary race for Kentucky's 4th Congressional District against Trump-backed Ed ...

    May 19Open →
  • Breaking down the heated Massie-Gallrein primary race in ...youtube.com

    President Trump is pulling no punches as he backs former Navy SEAL Ed Gallrein against incumbent GOP Rep. Thomas Massie in the primary for Kentucky's 4th ...

    May 19Open →
  • Thomas Massie LIVE: 'I'll Even Let Donald Trump…' GOP ...youtube.com

    Thomas Massie Speech LIVE | Kentucky Primary Rally LIVE | Trump vs Massie | GOP Civil War | Ed Gallrein | US News Watch live coverage as Republican ...

    May 19Open →
  • Full interview: GOP Rep. Thomas Massie on Israel, Trump and ...cbsnews.com

    Republican Rep. Thomas Massie is bearing the brunt of the White House in his primary race for Kentucky's 4th Congressional District against Trump-backed Ed ...

    May 19Open →
  • The Republican primary everyone's watching: Thomas Massie ...youtube.com

    The race is Kentucky's 4th Congressional District has turned into one of the most expensive and closely watched primaries in the U.S. After more than a ...

    May 19Open →
  • Kornacki: Gallrein victory over Massie in Kentucky primary ...youtube.com

    Voters are heading to the polls in six states today as President Trump tests his grip over the Republican Party. NBC News correspondents Monica Alba, ...

    May 19Open →

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

4

Why the gap existed

Prism's 5.4% edge call was wrong — market was right

CALIBRATION SCORECARD
PRISM ACCURACY
0.175
MARKET ACCURACY
0.133
EDGE
-42.2
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 Will Thomas Massie be the Republican nominee for KY-04?, classifying it as underpriced at 36.5%.
2.Forecast classification: MODERATE UNDERPRICED — PRISM estimate 41.9% vs market 36.5%.
3.Kelly reference at forecast time: —% (¼ Kelly, capped at 5%; mathematical reference only — not a position recommendation).
4.Outcome: resolved NO.

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: v0.9.129-official-resolver-evidence·Forecasted: May 19, 2026·Resolved: May 20, 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.