Polymarket reports favorites won 98.4% of US midterm markets

Polymarket settled 487 US midterm election contracts by Wednesday morning, with the favored outcome winning in 484 of them — a 98.4% hit rate across races spanning Senate seats, House districts, and governor's offices.

The platform reported the figure as a measure of market calibration rather than predictive edge. When a contract trades at 90% or higher, the underlying outcome is expected to resolve in that direction the overwhelming majority of the time. A 98.4% rate across nearly 500 markets is consistent with that baseline, though Polymarket did not break down results by probability tier.

The number does not distinguish between markets where the favorite was priced at 95% and those where it was priced at 51%. Without that distribution, the headline figure is difficult to evaluate as a calibration claim.

Global tech stocks fell on Wednesday as investors weighed Democratic congressional gains and the prospect of tighter oversight on data centre construction and AI infrastructure spending. The sell-off added pressure to a sector already managing concerns about AI capital expenditure returns, with the index moves registering before European markets closed.