The US government shutdown game highlights the issue of "definition accuracy" in prediction markets, with Polymarket and Kalshi diverging due to differences in definitions.

ChainCatcher News reports that, according to CoinDesk, as the U.S. Congress fails to complete all legislative procedures for the funding bill, the U.S. government is expected to enter a short-term partial shutdown starting from Saturday Eastern Time. However, this event also highlights issues in prediction markets regarding the “definition accuracy” of contracts. The prediction contracts on Polymarket and Kalshi about “whether the U.S. government will shut down” differ due to varying trigger condition definitions. The relevant contract on Polymarket shows a shutdown probability of about 88%, while the similar contract on Kalshi indicates a probability of up to 93%. The reason may be that some contracts consider an official announcement of a shutdown by the U.S. Office of Personnel Management (OPM) as the settlement basis, even if it is only a partial shutdown. This incident still underscores that prediction markets are highly sensitive to contract trigger conditions, official confirmation entities, and timing in macro events. Contract details themselves have become a significant factor influencing odds.