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Market study finds similar platform accuracy but flags ladder pricing distortions

PredictDesks reports its study of 358,236 resolved markets, 333,464 on Polymarket and 24,772 on Kalshi, found the favourite won 76.9 percent of the time across all markets and 92.8 percent a day out on long-running markets. Weighted to the same mix of topics, the two platforms' Brier scores were nearly identical at 0.150 for Polymarket and 0.147 for Kalshi, while ladder markets were overconfident, with outcomes priced under 10 cents winning 1.6 times as often as their price implied.

A study of 358,236 resolved markets found that favourites won 76.9 percent of the time, according to PredictDesks. Its comparison also found nearly identical accuracy scores for Polymarket and Kalshi after adjusting for their mix of topics.

Platform comparison and timing

The study covered 333,464 markets on Polymarket and 24,772 on Kalshi, according to PredictDesks. The findings therefore draw on substantially different numbers of resolved markets from the two platforms.

When weighted to the same topic mix, Polymarket’s Brier score was 0.150, compared with 0.147 for Kalshi. That near match is distinct from the study’s overall favourite win rate: the figures describe different aspects of the results.

For long-running markets measured a day out, the favourite won 92.8 percent of the time, PredictDesks found. That result applies to a narrower group and a specific measurement point, rather than to all markets in the sample.

Ladder markets show a pricing gap

PredictDesks also identified overconfidence in ladder markets. Outcomes priced under 10 cents won 1.6 times as often as their prices implied.

That finding sits alongside the high overall favourite win rate. Frequent favourite victories did not eliminate the pricing discrepancy identified among low-priced ladder outcomes.

What it means for prediction markets

  • Topic mix matters: The nearly identical platform scores—0.150 for Polymarket and 0.147 for Kalshi—came after weighting both to the same mix of topics.
  • Timing changes the comparison: The 92.8 percent favourite win rate concerns long-running markets a day out; the 76.9 percent figure covers all markets studied.
  • Low-priced outcomes warrant separate scrutiny: In ladder markets, outcomes below 10 cents won 1.6 times as often as their prices implied, highlighting a gap between pricing and observed results.
KalshiPolymarketInfiniti MarketsInfiniti Signals

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    PredictDesks
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