Italy’s referendum on December 4 will give voters the opportunity to approve or reject what some have described as the country’s most extensive constitutional reforms since the abolition of the monarchy at the end of World War II. Yet it may be the fact that Italy’s three opposition parties all favour exiting the euro that explains why Prime Minister Matteo Renzi has promised to resign if voters reject the reforms.

Understandably, after the surprise victory in June of the Leave campaign in the United Kingdom's Brexit referendum, and of Donald Trump in the United States' presidential election, no one has much faith in polls in advance of the Italian vote. There is, however, a disquieting real-time poll of investors' sentiment: capital flight from Italy has accelerated this year.