Most Asian stocks struggled higher on Monday but investors were rattled by news that the FBI is planning to review more emails related to Democratic presidential candidate Hillary Clinton's private server, just a week before the election.
European markets also looked set for a shaky start, with financial spreadbetter CMC Markets expecting Britain's FTSE 100, France's CAC 40 and Germany's DAX <.GDAXI to all open down 0.1 percent.
Federal investigators have secured a warrant to examine newly discovered emails, a source familiar with the matter said on Sunday.
Clinton had opened a recent lead over her unpredictable Republican rival Donald Trump in national polls, but it had been narrowing even before the email controversy resurfaced. An ABC News/Washington Post poll released on Sunday showed Clinton with a statistically insignificant 1-point national lead.