Prediction market pricing is diverging sharply on two high-profile U.S. political questions ahead of the 2026 midterms, with Kalshi and Polymarket assigning very different odds depending on contract definitions and time windows.
Kalshi's contract for a federal government shutdown at 10:00 a.m. ET on October 1, 2026, was priced at 15–16 cents by late August, implying roughly a 10% probability—down from 35% three weeks earlier. Polymarket's comparable shutdown market was around 16.5 cents as of August 14. However, the two venues resolve on different triggers: Kalshi requires a shutdown specifically at 10:00 a.m. on October 1, while Polymarket has separate contracts, including a broader any-duration lapse market that traded at 13.5 cents.
The repricing path is notable. Kalshi commentary put October 1 shutdown odds at 35% on July 31, then a cross-venue average of 28% by August 3, and later just 12–13% on about $193,000 in contract volume. Traders are not pricing the end of shutdown risk, but rather that Congress may avoid the specific October 1 deadline. A Polymarket market bundling a shutdown by January 31, 2027 with control of the House showed no-shutdown legs settling at zero, while a shutdown-plus-Democratic-House leg traded at 87.3 cents.
On impeachment, Polymarket's long-dated contract for the House to pass an article of impeachment before January 20, 2029 was around 68% on roughly $94,463 in volume since March 19, 2026. A separate contract capping the window at December 31, 2026 traded near 2%—a 33x spread. The difference is congressional arithmetic: the current Republican-controlled House has little incentive to advance impeachment, while a Democratic flip after the 2026 midterms would open subpoena power and Judiciary Committee control. Prediction market traders separately put Democratic House control at roughly 85–87%.
The contracts resolve on House passage alone; Senate conviction and removal require a two-thirds vote and are separate questions. The Congressional Research Service notes the House has impeached three presidents—Andrew Johnson, Bill Clinton, and Donald Trump twice—while the Senate declined to convict in each case. Current liquidity remains thin compared with 2025, when Polymarket's shutdown start-date market cleared about $157 million in cumulative volume.
