The British pound is now the worst performing currency of the year, down nearly 16% this year and to its lowest level in 31 years against the U.S. dollar. A flash crash of 6% in early Asian trading on October 7 spooked investors further, though the currency has recovered 5% from its low.

In a speech at her Tory party conference earlier this month, Prime Minister Theresa May promised to carry through with Article 50 by March of next year, starting the process of the UK's exit from the European Union.

The speech surprised many that were still hoping for some kind of reconciliation, or at least a slower exit from the monetary group.

The announcement has also heightened fears that the UK may not have time to work out trade deals with the EU or the United States before the exit removes valuable trade preferences.