Currency traders are rushing to put hedges in place to guard against potentially big FX market moves when the results of the election start trickling in later.
Options contracts which focus on volatility in the euro and Mexican peso - two parts of the world that could be hit with huge tariffs if Donald Trump wins - have hit highest since he last won the White House in 2016.
And in China, where Trump has pledged to impose 60% tariffs, overnight yuan volatility contracts are close to their highest since at least 2012.
Trump and Democrat Kamala Harris remain virtually tied in opinion polls and the winner might not be known for days, weeks or even months after voting ends.
Analysts believe Trump's promises to cut immigration, slash taxes and impose punitive trade tariffs would cause global disruption and drive up inflation and the dollar.
Harris is broadly seen as the continuity candidate for markets, although economists predict her domestic spending policies could also push up inflation.
