This article applies event-study methodology to explore the economic consequences of cartelisation in Imperial Germany. By combining qualitative and quantitative sources it discusses the risk and return effects of the establishment of the allegedly most powerful cartel, the Rhenish-Westphalian Coal Syndicate (RWKS). Its findings cast doubts on the importance of the RWKS for the development of the German coal industry. The cartel did not affect the major part of a typical mine's risk-the firm-specific risk – and its moderate return effects were mostly confined to larger mines. Cartelisation did not seem to be an important pillar of ‘organised capitalism’.