East African Breweries’ dominance of the brewing business is but one example of how east Africa’s biggest economy is distorted by the market power of a few big firms. It is a problem common in many other African countries, where markets are often small and fragmented, competition regulators are weak and barriers to entry are high. Another example is Safaricom, a mobile-phone operator with a 66% share of the Kenyan market. This dominance may explain why it is so profitable. Over the past five years its average return on equity (roe) was a mouthwatering 47%. That compares with an average roe of about 10% on mobile-phone operators in America, according to Aswath Damodaran, a finance professor at New York University.