Bad old habits have returned. As investors search desperately for yield, they have piled into African bonds. In 2013-16 the ratio of public debt to GDP in sub-Saharan Africa, as defined by the IMF, increased by an average of five percentage points a year for countries that do not produce oil, and eight for those that do. It is now above 50% in half of the countries in the region. That is modest by rich-world standards, but commercial interest rates are much higher in Africa. Since 2013 the number of countries that the IMF deems to be in “debt distress” or at high risk of it has doubled to 14.