This year, we sent our questionnaire to more than 14,000 companies active on the continent. After cross-checks and verification, we established a ranking of approximately 1,500 companies, which includes responses from previous years. The top-ranking 500 are published here. To allow for comparison, we apply the same rules to all our data: 1) All financial data must have a clearly defined source, generally communicated to us by the companies themselves, and must refer to the year 2017 (in some cases 2017/2018);
2) If presented in the local currency, we convert the data into US dollar amounts according to the rate on 31 December 2017; 3) We include all companies that fall under the legal jurisdiction of at least one of the 54 countries in Africa, which is why a holding company and a subsidiary can both feature in the list; and 4) Where we cannot obtain up-to-date figures, we use those of the previous year (marked with an asterisk and italics). After two years of silence, a company is struck off the rankings.