Banks worldwide are warning of the financial folly that would follow Scotland’s decision to exit the United Kingdom. Scotland’s big banks talk of relocating to London, and other businesses are watching currency and economic ripples as the decision nears.

Scotland’s population of 5 million will go to the polls on September 18 to decide whether or not to break its 307-year union with the United Kingdom. If a majority vote “Yes” Scotland will only be part of the United Kingdom for another 18 months before establishing independence.