With the commencement of the amendment of the Swiss Cartel Act on 1 April 2004, the Competition Commission gained considerably new powers, especially with respect to the possibilities to sanction anticompetitive behaviour by imposing substantial fines. In order to review the success of the amendment and its implementation, Article 59a of the Swiss Cartel Act requires the Federal Council of Switzerland (‘Bundesrat’) to evaluate the effectiveness and execution of the provisions. Within this extensive overall project, it is the aim of the present subproject to investigate the economic effects of intervening and non-intervening decisions as well as the consequences of these decisions for the affected parties and markets in particular cases. Following the structure of the Cartel Act, case studies are undertaken in the fields of cartel agreements, abuses of dominant positions, vertical agreements as well as horizontal mergers.