Prediction markets perfectly telegraphed the Green Party's stunning victory in Gorton and Denton, with margins baked into the odds before ballots were counted. The winning margin market swung dramatically to 97¢ for 9-12% margin, up from 13¢, while second-place markets showed Reform UK at 99¢, rising from 64¢. These movements preceded the official result: GRN 40.7%, REF 28.7%, LAB 25.4% — a precise match to trader expectations.

The result represents the sixth largest Labour majority overturned at a by-election since World War II, transforming a Labour stronghold held for generations with a 13,413 majority in 2024 into a Green gain. Starmer described the result as "very disappointing", while markets had already processed the electoral earthquake before official confirmation.