Unlock the Editor’s Digest for freeRoula Khalaf, Editor of the FT, selects her favourite stories in this weekly newsletter.The writer is chief executive of the Nordic Institute for Finance, Technology and SustainabilityCurrency risk is the Achilles heel of developing economies that borrow to make investments to increase productivity, reduce emissions and meet sustainable development goals. About 90 per cent of cross-border debt for low and lower-middle income countries, nearly $2tn, is denominated in hard currencies, mostly dollars, much of it from development banks and other official lenders.But this exposes vulnerable populations...