London's FTSE 100 stock market index's 13 per cent surge so far this year, driven by exporters such as Guinness's parent Diageo and drugmaker GlaxoSmithKline benefiting from a weaker sterling, looks less impressive when translated into euro or dollars.

Irish investors who committed money to the UK’s blue-chip stock index at the start of this year are now sitting on a 4.5 per cent decline on their investments, driven by sterling’s slump against the euro following the Brexit referendum.

"This highlights the challenge for investors as a result of sharp currency moves," said David Holohan, chief investment officer at Merrion Capital in Dublin. "An [Irish] investor can have a very strong share price performance [in a UK stock] but when converted back to euros the performance can be very different."

Oil and mining companies

While the UK's decision to quit the European Union in June has prompted a swathe of economists to cut their economic forecasts for the country, the dominance of exporters and dollar-exposed oil and mining companies in the FTSE have seen the London benchmark stand out as a strong spot across European markets.

The Iseq index has fallen by more than 10 per cent this year, leaving it on track for its first negative performance in six years.