The world’s dependency on cobalt mines in Congo and cobalt refineries in China is seen as serious security issues with potentially dangerous implications for the energy transition. However, Chinese refineries have a similar supply security issue as most of its cobalt concentrates are imported. Most supply security studies take a country perspective on market concentration and supply risks. However, control of the mines and refineries lies with the producing companies, not the governments of the countries where they are located. This paper analyses the corporate structure of the cobalt industry at the mine and the refinery stages over a longer time period to establish changes in the level of corporate concentration and to put the situation in 2018 in perspective. The level of corporate concentration at the mine stage is low and does not raise concerns for market failures or a lack of competitiveness. Corporate concentration of refined cobalt depends on the Chinese government’s influence over Chinese production: if the state control over individual refineries is assumed to be strong, the corporate concentration is high. Mine stage supply security could be strengthened by improving the general political stability in the DRC to make the country more attractive for investors other than the present ones. Increased local beneficiation would strongly benefit Congo and reduce China’s influence. This is a long and complicated process and its success is not at all certain. At the refinery stage, the solution is much easier: reliability of supply could be improved by constructing refineries in countries outside China.