How accurate are prediction markets?

In June 2026, 60% of the 40 highest-volume Polymarket markets resolved to the outcome that was priced above 50% a day before close, with a Brier score of 0.253.

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: June 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 01:56 UTC · Source: Polymarket · 18+

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

Favorites that won

60%

24 of 40 markets where the eventual result was priced above 50% a day before

Brier score (1 day out)

0.253

0 is perfect, 0.25 is a coin flip

Markets graded

highest-volume resolutions, June 2026

Resolved markets, June 2026

Market	Result	1 day before	7 days before	Volume
US strikes Iran by...? resolved February 28, 2026	March 31	54.5%	61.5%	$529.0M
2026 NBA Champion resolved June 14, 2026	New York Knicks	80.8%	78.3%	$426.9M
Next Prime Minister of Ethiopia? resolved October 6, 2026	Abiy Ahmed	97.4%	97.0%	$286.1M
Fed Decision in June? resolved June 17, 2026	No change	99.6%	99.4%	$164.6M
Israel x Hezbollah ceasefire by...? resolved April 21, 2026	April 18	100.0%	–	$112.6M
NBA MVP resolved May 18, 2026	Shai Gilgeous-Alexander	97.8%	97.5%	$95.2M
2026 NHL Stanley Cup Champion resolved June 15, 2026	Carolina Hurricanes	79.5%	36.5%	$82.8M
Will the Iranian regime fall by June 30? resolved July 1, 2026	No	100.0%	99.8%	$65.9M
Russia x Ukraine ceasefire by June 30, 2026? resolved May 9, 2026	Yes	34.5%	9.5%	$60.7M
Monad FDV one day after launch? resolved November 25, 2025	>$2B	91.0%	93.3%	$53.8M
2026 Seoul Mayoral Election Winner resolved June 4, 2026	Oh Se-hoon	19.5%	21.5%	$52.2M
Türkiye vs. United States resolved June 26, 2026	Türkiye	25.5%	34.5%	$47.1M
Trump announces end of military operations against Iran by ...? resolved May 1, 2026	June 30	43.5%	65.5%	$44.7M
Colombia Presidential Election resolved June 24, 2026	Abelardo de la Espriella	99.4%	87.5%	$44.4M
Strait of Hormuz traffic returns to normal by end of June? resolved July 7, 2026	No	100.0%	99.6%	$44.1M
South Africa vs. Canada resolved June 28, 2026	Canada	55.5%	–	$44.1M
Germany vs. Côte d'Ivoire resolved June 20, 2026	Germany	63.5%	63.5%	$42.5M
What price will Bitcoin hit in May? resolved May 4, 2026	↑ 80,000	82.5%	–	$42.2M
2026 Men's French Open Winner resolved June 7, 2026	Alexander Zverev	78.0%	40.4%	$42.2M
Germany vs. Paraguay resolved June 29, 2026	Draw (Germany vs. Paraguay)	17.5%	–	$41.4M
Ecuador vs. Germany resolved June 25, 2026	Ecuador	24.3%	19.5%	$40.1M
Japan vs. Sweden resolved June 26, 2026	Draw (Japan vs. Sweden)	27.0%	27.5%	$39.7M
United States vs. Paraguay resolved June 13, 2026	United States	47.5%	49.5%	$39.3M
Norway vs. Senegal resolved June 23, 2026	Norway	42.5%	45.5%	$37.7M
Belgium vs. Egypt resolved June 16, 2026	Draw (Belgium vs. Egypt)	23.5%	24.5%	$36.0M
Trump announces US blockade of Hormuz lifted by...? resolved June 15, 2026	June 30	74.5%	39.5%	$35.7M
Spurs vs. Knicks resolved June 11, 2026	Knicks	53.5%	–	$35.4M
Spain vs. Cabo Verde - More Markets resolved June 15, 2026	Cabo Verde	27.5%	27.0%	$35.0M
Will Crude Oil (CL) hit__ by end of June? resolved May 28, 2026	↓ $90	86.0%	64.5%	$34.3M
Brazil vs. Japan resolved June 29, 2026	Brazil	57.5%	–	$34.0M
Czechia vs. South Africa resolved June 18, 2026	Draw (Czechia vs. South Africa	25.5%	28.5%	$33.3M
IR Iran vs. New Zealand resolved June 16, 2026	Draw (IR Iran vs. New Zealand)	28.5%	28.5%	$32.8M
Türkiye vs. Paraguay resolved June 20, 2026	Paraguay	24.5%	23.5%	$32.6M
Spain vs. Cabo Verde resolved June 15, 2026	Draw (Spain vs. Cabo Verde)	7.1%	7.1%	$32.5M
Morocco vs. Haiti - More Markets resolved June 25, 2026	Morocco	60.5%	52.5%	$32.3M
Argentina vs. Austria resolved June 22, 2026	Argentina	64.5%	62.5%	$32.1M
Spurs vs. Knicks resolved June 9, 2026	Spurs	45.5%	–	$30.5M
France vs. Sweden - More Markets resolved June 30, 2026	France	53.5%	–	$29.6M
France vs. Iraq - More Markets resolved June 23, 2026	France	75.5%	70.5%	$29.2M
France vs. Senegal resolved June 16, 2026	France	66.5%	66.5%	$28.9M

"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 June 2026, 60% of the 40 highest-volume Polymarket markets resolved to the outcome that was priced above 50% a day before close, with a Brier score of 0.253.
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.