Investment giant Morgan Stanley has been weighing up its options should the UK vote to leave the EU today, and a move this side of the Irish Sea could be on the cards.

According to the bank's president Colm Kelleher, the New York-based Morgan Stanley could opt to move its European headquarters to either Dublin or Frankfurt if a Brexit comes to pass.

Kelleher, who was interviewed on Bloomberg Television yesterday, said:

"This will be the most consequential thing post-war we’ve ever seen.

"Initially, the fallout can be controlled, but the political ramifications are actually quite profound.

"We’re hoping the British voter will show sense and listen to the economic arguments and stay. But we clearly are looking at our plans."

Kelleher admitted he fears for London if the UK pulls out, and forecasts that extended low interest rates and stagnant growth would see the markets would fail to climb or return to higher trading volumes.

Polls are now open across the UK, with voters being asked:

"Should the United Kingdom remain a member of the European Union or leave the European Union?"

A YouGov poll published in The Times (London) shows 51% support a remain vote, with 49% indicating that they want to leave.

Keep up to date with our special Brexit programme on Newstalk from 10pm until midnight tonight, with coverage continuing through the night via LBC radio London. Find all the latest stories and analysis on Newstalk.com, and you can also follow @Newstalkfm, @ShonaMurrayNT and @newschambers for up-to-the-minute updates