Of all the mugs’ games in finance, currencies top the lot. But since the start of the credit crunch at least the rules of the game have been pretty straightforward. If the world was becoming riskier, you bought the dollar or the yen. On brighter days, conversely, traders piled into higher-risk currencies: the pound, for instance, or commodity plays such as the Australian dollar.

In the past few weeks, however, confusion has returned. Sure, the commodity currencies have responded to talk of “green shoots”. But the yen, for example, has been strengthening since equities bottomed in March. Over the same period, the dollar rallied against the euro but is now back to where it was. Sterling, too, is all over the place versus the euro. Still, bewildered traders could be interpreted as a positive sign that normality is returning to markets.