U.K. stocks finished in negative territory Monday, weighed down by a gain in the pound after a fresh poll signaled a double-digit lead for the governing Conservative Party as a general election nears. A terror attack in London over the weekend added to the uncertainty around Thursday's parliamentary vote, but the Guardian/ICM poll out Monday suggested a change in government is unlikely.

U.S. stocks closed lower Monday, slightly below record levels, as investors grappled with a variety of geopolitical issues, such as terrorist attacks in London ahead of the U.K. election and the scheduled public testimony of fired Federal Bureau of Investigation Director James Comey.

Equity markets across Asia were lower early Tuesday, tracking overnight declines in the U.S., as cautious investors looked ahead to elections in the U.K. and a European Central Bank meeting. Investors are also looking for any fallout from former Federal Bureau of Investigation Director James Comey's public testimony about alleged Russian interference in the 2016 election. Comey's testimony is scheduled for Thursday, as are the U.K. elections and the ECB meeting.