Uniswap founder explains prediction market pricing differences: Not due to user structure, but possibly caused by differences in event definitions and rules

According to Odaily, Uniswap founder Hayden Adams posted on X, pointing out that the prediction market Kalshi prices the probability of "the United States acquiring Greenland" at about 42%, while Polymarket prices it at only 15%–23%. Such a significant price difference does not stem from differences in user groups, but rather from differences in the specific betting targets themselves. If it were merely a difference in user structure, a single trader with access to both platforms could quickly arbitrage and eliminate the price gap. However, the actual situation may be: Polymarket is pricing the "probability of occurrence by 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. In addition, differences in question phrasing, settlement conditions, oracle design, and different risk pricing logic can all lead to different pricing.