Uncertain Bets on Greenland, Venezuela Test Prediction Markets

Prediction markets are on a hot streak — with rising volumes, growing attention, and bets on everything from elections to military raids. But as these platforms scale, they’re running into a harder problem: how to write rules that match the messiness of real-world events.

One of the most traded contracts right now isn’t about war or inflation, but Greenland.

On Polymarket, traders have poured more than $2.4 million into bets on whether the US will acquire sovereignty over the Arctic island by year-end, with odds at 16% on Wednesday. On Kalshi, a regulated US exchange, a related market — ...