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Which country has the most to lose from Brexit?

Ireland will bear the brunt of a "Brexit" more than any other U.K. trading partner, according to a "sensitivity index" from U.S. ratings agency Standard & Poor's.

The ratings agency's index, released this week, measured goods and services exports to the U.K. from 20 countries most exposed to a potential exit from the European Union – looking at their economies, migrant flows, financial sector claims on U.K. counter-parties and foreign direct investment in the U.K.

British citizens are set to cast their vote on June 23 in a EU referendum to decide on whether the UK should stay in or leave the 28-member bloc, and according to the report, Ireland is the economy that will be most "susceptible to any trade and migratory aftershocks from a decision by the U.K. to leave."

Ireland will feel the most significant reverberations to its economy, said S&P. "The uncertainty regarding its [Ireland] new trade and migratory agreements with Europe would take its toll on flows of merchandise, services, and human capital, along the Republic of Ireland's 499 kilometer border with the U.K."

However, the glass is not completely half-empty. "We would expect that Ireland's highly flexible economy would manage to reorient trade toward even larger trading partners (such as the remaining EU and the U.S.) in the unlikely event that an exited U.K. would not reach new terms on trade access to the EU after its departure," according to the Index.

Malta, Luxembourg and Cyprus all follow closely behind in terms of effects to their economies should Brexit occur. Malta and Cyprus, both of whom enjoy historical relations with the U.K., also benefit from high tourism and large expat populations from the U.K. to their countries.

"Their attractive climates have drawn a large population of U.K. pensioners… Cyprus also has a very large expat population working in the U.K., which pays an estimated 0.6 percent of GDP (gross domestic product) in remittances to Cyprus per year, the highest in Europe outside of the Baltics," according to S&P.

Another vulnerable economy is Spain. "Spain has large financial and FDI (foreign direct investment) exposures to the U.K., in particular through its large retail banking subsidiaries and telecom operations," said the ratings agency.

And similar to its fellow Mediterranean countries, Spain also relies on a huge amount of British tourists and expats to subsidize its income.

Recent polls in the U.K. show that voters are tied over the issue. The result is expected on June 24.


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