Are your European assets Greek euros, or Spanish euros, or Finnish euros, or German euros? The defining feature of a single currency is that no one asks that question. They do not distinguish Massachusetts dollars from Californian dollars and they do not – yet – ask whether the pounds they hold are Scottish or English.
But now they do ask that question of the euro. When countries joined the single currency, a relatively simple piece of domestic legislation converted contracts in drachmas, pesetas, markkas and Deutschmarks into contracts in euros at a prescribed exchange rate. But you cannot simply reverse that process when countries leave the single currency. You have to prescribe which contracts are now to be fulfilled in drachmas and which remain in euros or converted into Deutschmarks. That determination is politically fraught, technically complex and subject to long legal challenges.
About two years ago some large businesses and wealthy individuals began seriously to ask, “if the euros were to unwind, in which currency would my asset or contract be denominated?” The issue is not whether the euro coins in your pocket carry an Athenian owl or German imperial eagle. The issue is the status of bank deposits and loans, residential mortgages and commercial contracts, as well as wages and prices. The drain of funds from Greek banks is an indication that ordinary people are now thinking in these terms.