We examine the effect of one of the presumably most powerful cartels ever on the profitability of its members. More precisely, we consider the Rhenish-Westphalian Coal Syndicate, a coal cartel that operated in Imperial Germany in the late 19th and early 20th century, using a newly constructed dataset and two different methodological approaches. At first, we employ event study methodology to asses the reaction of the stock market to the foundation of the cartel and two major revisions of its original contract.