Nigeria’s central bank has moved towards a single exchange-rate system, having maintained a multiple rate for several years to avoid an outright devaluation of the naira. Late last month, the Abuja-based bank replaced the fixed 379 naira to the dollar rate for official transactions, which triggered an immediate weakening in the currency. However, the unification of the rates is expected to improve the country’s currency-management system and help meet the conditions of the International Monetary Fund and investors for greater transparency. Photograph: Bloomberg