In order to secure a proper execution of sporting competitions, national governing bodies of professional football leagues apply specific regulatory procedures. In this context, special focus is placed on requirements that are supposed to ensure financial stability of clubs. They, in turn, help avoid negative economic externalities, i.e. the problem that financial difficulties from one club can affect other clubs and stakeholders due to the interdependent relationships of the competition. These regulations on a national level in European professional football leagues show several significant differences. Therefore, the aim of this paper is to comprehensively analyze financial regulatory procedures of professional football leagues to generat...