British Prime Minister Theresa May's narrowing lead in opinion polls ahead of today's election has weakened sterling and raised questions over whether she will win the landslide predicted just over a month ago.
The vote will decide whether May or her Labour Party rival Jeremy Corbyn takes control of Britain's exit from the European Union - a two-year negotiation which will plot a new course for the $2.6tn economy.
The prime minister called the snap election in a bid to strengthen her hand in Brexit negotiations, to win more time to deal with the impact of the divorce and to strengthen her grip on the Conservative Party.
While she is still expected to win, with a lead of between one percentage point and 12 points in polls released over recent days, financial markets are now digesting a bigger range of outcomes than they previously had considered.
Landslide May victory
Sterling rallied in April when May called the vote as investors bet her then-large poll lead would translate into a big majority, reducing uncertainty over whether she would have the mandate required to negotiate on Britain's behalf and then drive the deal through parliament.
The snap election pushes back the date of the next planned national election from 2020 - just after Britain is due to have quit the EU - to 2022, giving May more time to put the exit deal in place and potentially reducing political risk over how the deal is implemented.
Some also take the view that a big majority would allow her to make compromises with Brussels, in contrast to a hardline approach to date that has prioritised issues like immigration and trade over access to Europe's lucrative single market.
UK election polls open for #GE17 amid high security. More: https://t.co/WMxMstAYYa via @ReutersTV pic.twitter.com/f7Hf7SkpR1
— Reuters Top News (@Reuters) June 8, 2017
May wins with enhanced majority
The Conservatives' lead fell sharply after May announced plans to make elderly voters pay more towards their old-age care, while Corbyn has gained ground thanks to popular policies such as renationalisation and higher taxes for the rich. Whilst still broadly predicting May will improve on the 12-seat victory her predecessor David Cameron won in 2015, the narrowing polls suggest a majority that might fall well short of a 100-seat or more landslide. Bank analysts say that would not undermine the central scenarios which have helped the pound in the past month but might struggle to drive it much higher.May wins but no overall gains
If May does not handsomely beat the 12-seat majority Cameron won in 2015, her electoral gamble will have failed, her ability to drive Brexit reform through parliament will be diminished and she will go into talks later this month looking weaker. The converse view is that with less room for manoeuvre domestically, she will be able to reject compromises proposed by Brussels and drive a harder bargain, knowing that EU negotiators will not want May to execute her threat of leaving without a deal. For investors the over-riding factor is likely to be greater uncertainty about whether there will be a deal on Brexit and what it will look like. Citi said anything less than a 40-seat majority could increase political risks and uncertainty for the Brexit process, pushing sterling lower.Polls open in heated UK election https://t.co/Dsj8RArDQJ #GE2017 pic.twitter.com/dYTA15owgV— Al Jazeera News (@AJENews) June 8, 2017
Hung parliament
If neither main party wins a clear majority, markets will have to deal with considerable uncertainty over who will form the next government and what compromises the eventual prime minister will have to make to get the support of other parties.
The Conservatives' positioning on Brexit and, to a lesser extent other domestic issues like austerity, makes it unlikely that it could find a willing coalition partner, making a Labour-led government the most likely outcome from a hung parliament.
Today's the big day! Are you voting Labour? Let your friends know by sharing this. Polls are open 7am 'til 10pm ↓ #VoteLabour #ForTheMany pic.twitter.com/XafxSljCs7
— The Labour Party (@UKLabour) June 8, 2017
Corbyn victory
A clear win for Corbyn, whose less than two-year-old leadership has been marked by poor ratings, divisions among his party and a failed coup attempt, would force many investors to redraw their assumptions on both Brexit and the fiscal outlook.
History shows that sterling tends to weaken on big moves towards Labour in the polls and analysts and London-based traders say they would be braced for an immediate dive in the pound if Corbyn won.
Longer term, however, analysts from a number of banks highlight the potential for both more borrowing to fund economic stimulus and the increased likelihood that Corbyn will negotiate a closer trading relationship with the EU than May would have done.