How accurate are prediction markets?

In November 2026, 76% of the 34 highest-volume Polymarket markets resolved to the outcome that was priced above 50% a day before close, with a Brier score of 0.163.

What is a Brier score?

The average squared difference between the forecast probability and the outcome (1 if it happened, 0 if not). Lower is better; a constant 50% forecast scores 0.25.

Which markets are included?

Resolved Polymarket events with more than $50K of volume in the selected window, up to 40 per month, graded on the price one day and one week before close.

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Resolved markets

Prediction market scorecard: November 2026

For every high-volume market that resolved, we record what Polymarket priced the eventual outcome at one day and one week before close. This is the record, good and bad.

Updated 2026-11-06 02:01 UTC · Source: Polymarket · 18+

Last 30 days Nov 2026 Oct 2026 Sep 2026 Aug 2026 Jul 2026 Jun 2026

Favorites that won

76%

26 of 34 markets where the eventual result was priced above 50% a day before

Brier score (1 day out)

0.163

0 is perfect, 0.25 is a coin flip

Markets graded

highest-volume resolutions, November 2026

Resolved markets, November 2026

Market	Result	1 day before	7 days before	Volume
Balance of Power: 2026 Midterms resolved November 4, 2026	Democrats Sweep	75.5%	66.5%	$75.7M
Which party will win the House in 2026? resolved November 4, 2026	Democratic Party	94.5%	91.5%	$63.3M
California Governor Election Winner resolved November 4, 2026	Xavier Becerra	98.2%	96.7%	$44.9M
Which party will win the Senate in 2026? resolved November 4, 2026	Democratic Party	76.5%	66.5%	$31.5M
2026 Men’s US Open Winner (Tennis) resolved September 14, 2026	Alexander Zverev	57.9%	21.6%	$26.4M
Texas Senate Election Winner resolved November 4, 2026	James Talarico (D)	74.5%	67.5%	$21.8M
What price will Bitcoin hit in October? resolved October 1, 2026	↑ 85,000	–	–	$17.4M
LoL: Top Esports vs Invictus Gaming (BO5) - Worlds Playoffs resolved November 4, 2026	Invictus Gaming	51.5%	–	$15.9M
Michigan Senate Election Winner resolved November 4, 2026	Abdul El-Sayed (D)	80.5%	69.5%	$13.7M
LoL: Gen.G vs LYON (BO5) - Worlds Playoffs resolved November 5, 2026	Gen.G	81.5%	–	$13.6M
LoL: LOS vs LYON (BO3) - Worlds Group Stage resolved October 31, 2026	LOS	–	–	$9.6M
Eagles vs. Commanders resolved November 2, 2026	Commanders	70.5%	64.0%	$8.8M
AEK vs. Real Madrid CF resolved November 4, 2026	Real Madrid CF	78.5%	76.5%	$8.3M
LoL: Hanwha Life Esports vs Bilibili Gaming (BO3) - Worlds Group Stage resolved November 1, 2026	Bilibili Gaming	–	–	$7.8M
Texas Governor Election Winner resolved November 4, 2026	Gina Hinojosa (D)	39.5%	35.5%	$7.4M
Republican Senate seats after the 2026 midterm elections? resolved November 4, 2026	≤47	55.5%	40.0%	$7.2M
Bears vs. Seahawks resolved November 3, 2026	Bears	38.5%	39.0%	$6.9M
Florida Governor Election Winner resolved November 4, 2026	Byron Donalds (R)	64.5%	76.5%	$6.5M
Chiefs vs. Broncos resolved November 2, 2026	Broncos	47.5%	45.0%	$6.4M
Maine Senate Election Winner resolved November 4, 2026	Troy Jackson (D)	73.5%	63.5%	$6.2M
Thunder vs. Rockets resolved November 1, 2026	Rockets	63.5%	33.5%	$5.9M
What will WTI Crude Oil (WTI) hit in October 2026? resolved October 20, 2026	↑ $100	82.0%	32.0%	$5.8M
BV Borussia 09 Dortmund vs. Real Betis Balompié resolved November 4, 2026	BV Borussia 09 Dortmund	55.5%	53.5%	$4.9M
What price will Ethereum hit in October? resolved October 1, 2026	↓ 2,700	–	–	$4.9M
Dota 2: Team Yandex vs Team Spirit (BO5) - PARI Universe Playoffs resolved November 1, 2026	Team Spirit	–	–	$4.7M
Nebraska Senate Election Winner resolved November 4, 2026	Pete Ricketts (R)	67.5%	71.5%	$4.3M
Manchester United FC vs. AS Roma resolved November 3, 2026	Manchester United FC	41.5%	41.5%	$4.3M
Ravens vs. Bills resolved November 1, 2026	Bills	61.5%	63.0%	$4.1M
Ohio Senate Election Winner resolved November 4, 2026	Sherrod Brown (D)	71.5%	68.5%	$4.1M
South Carolina Senate Election Winner resolved November 4, 2026	Annie Andrews (D)	30.5%	20.5%	$4.0M
Cavaliers vs. Bucks resolved November 1, 2026	Cavaliers	74.5%	71.0%	$3.9M
Raiders vs. Jets resolved November 1, 2026	Raiders	46.5%	52.5%	$3.8M
Suns vs. Warriors resolved November 3, 2026	Warriors	62.5%	–	$3.8M
Thunder vs. Cavaliers resolved November 3, 2026	Thunder	39.5%	62.5%	$3.6M
Iowa Senate Election Winner resolved November 4, 2026	Josh Turek (D)	52.5%	43.5%	$3.5M
Counter-Strike: FURIA vs Natus Vincere (BO3) - IEM Beijing Group A resolved November 3, 2026	Natus Vincere	–	–	$3.5M
Chargers vs. Rams resolved November 2, 2026	Rams	72.5%	75.0%	$3.5M
Kansas Senate Election Winner resolved November 4, 2026	Adam Hamilton (D)	61.5%	38.5%	$3.5M
Counter-Strike: Natus Vincere vs Team Falcons (BO3) - IEM Beijing Group A resolved November 2, 2026	Natus Vincere	39.5%	49.0%	$3.4M
Hawks vs. Pacers resolved November 3, 2026	Hawks	63.5%	65.5%	$3.4M

"1 day before" is the Polymarket price of the outcome that eventually happened, 24 hours before the market was closed for resolution. Brier score averages (1 - price)² over graded markets.

How to read the scorecard

Calibration, not hit rate, is the real test: a market is doing its job if outcomes priced at 70% happen about 70% of the time, which means favorites should lose roughly 30% of the time at that price. A Brier score near 0.1 across a month is strong; 0.25 is no better than a coin flip. Sample sizes here are small, so treat one month as a snapshot. Methodology and the full court and enforcement data live in the tracker and editorial standards.

Frequently asked questions

How accurate are prediction markets?: In November 2026, 76% of the 34 highest-volume Polymarket markets resolved to the outcome that was priced above 50% a day before close, with a Brier score of 0.163.
What is a Brier score?: The average squared difference between the forecast probability and the outcome (1 if it happened, 0 if not). Lower is better; a constant 50% forecast scores 0.25.
Which markets are included?: Resolved Polymarket events with more than $50K of volume in the selected window, up to 40 per month, graded on the price one day and one week before close.