If proven to be right, the bulk of the move in the pound may come from what the exit polls says itself
The latest methodology of the exit poll has been adopted since 2005 and that has seen markets become increasingly reliant on it in terms of pricing in the election results - especially given the tight margin of error in its recent track record (h/t @ samueltombs):
The exit poll has a feel of clairvoyance around it and that makes it a powerful tool that markets will respond to. In 2017, the "big move" in the pound actually came in response to the exit poll itself rather than the results declaration (h/t @ FT):
The big question is how much will markets respond to it this year? That's something we can't say for sure but given its recent run of form, I would expect markets to take what it says at face value - though I would caution against overconfidence in the exit poll.
Given how tight the election looks to be this time around - whereby voting intentions seem to have it all wrong - it's hard to say if the exit poll will get it right and therein lies the risk if traders get too aggressive in pricing in the result later at 2200 GMT.
If anything, expect the pound to react strongly to the exit poll bias in the first two hours - with possible retracements after depending on the early results - but just keep it in the back of your mind that it is not over until the fat lady sings (actual results declared).
