India, Nov. 1 -- As the final hours of campaigning draw to a close ahead of November 3, financial markets are steeling themselves for an electoral showdown that will define the political landscape of the 120th US Congress. Early returns could show whether Democrats are on course for a large victory, though it may take days or even weeks to establish whether Republicans have held the House or Senate. The most informative races are concentrated in Florida, Virginia, Kentucky and Iowa, with Maine and Alaska likely to take longer to resolve.

With control of both the Senate and the House of Representatives hanging in the balance, Wall Street trading desks have mobilised round-the-clock monitoring teams to analyse fast-moving returns as poll c...