The Scarborough Southwest provincial by-election, triggered by former NDP MPP Doly Begum’s February 2026 resignation to run federally as a Liberal, features a tight three-way contest ahead of the September 3 vote. Fatima Shaban secured the NDP nomination in April after prior federal runs in the riding and maintains a narrow lead in trader pricing amid ongoing advance voting from August 26–28. Progressive Conservative nominee Dr. Noor Tarun and Liberal candidate Ahsanul Hafiz, who prevailed in a contested May nomination over MP Nathaniel Erskine-Smith, split support in a riding where the NDP previously held strong provincial results. The market’s clustered probabilities around 45–51 percent reflect uncertainty over turnout, local issue salience, and the absence of a dominant frontrunner following candidate finalization in August.