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

According to CoinDesk, as the U.S. Congress failed to complete the full legislative process for the funding bill, the U.S. government is expected to enter a short-term, partial shutdown starting Saturday Eastern Time. However, this event also highlights the issue of "definition precision" in prediction markets. The prediction contracts on Polymarket and Kalshi regarding "whether the U.S. government will shut down" show differences due to varying definitions of triggering conditions. The relevant contracts on Polymarket indicate a shutdown probability of about 88%, while similar contracts on Kalshi have a probability as high as approximately 93%. This discrepancy may be because some contracts consider the formal announcement of a shutdown by the Office of Personnel Management (OPM) as the basis for settlement, meaning that even a partial shutdown is regarded as valid. This event underscores the sensitivity of prediction markets to contract triggering conditions, official confirmation entities, and timelines in macro events, with the details of the contracts themselves becoming an important factor influencing the odds.