Uniswap Founder Explains Pricing Differences in Prediction Markets: Not Due to User Structure, Possibly Caused by Event Definitions and Rule Variations

Odaily News Uniswap founder Hayden Adams posted on X, pointing out that the prediction market Kalshi prices the "US acquisition of Greenland" at about 42%, while Polymarket prices it at only 15%–23%. Such a significant price difference does not stem from user base differences but rather from variations in the specific betting subjects themselves. If it were merely a difference in user structure, a single trader with access to both platforms could quickly arbitrage away the spread. However, the actual situation might be: Polymarket is pricing the "probability of occurrence within 2026 (currently about 23%)", while Kalshi is pricing the "probability of occurrence during Trump's entire term (currently about 45%)". These are not the same event. Furthermore, differences in problem formulation, settlement conditions, oracle design, and different risk pricing logics can all lead to pricing discrepancies.