The pros and cons of merger control are high on the agenda of policymakers, competition authorities, academics, representatives of industryand labour organizations, and others. The views and concerns on corporate concentrations also span a wide range, covering at one extremescrapping merger control altogether, and at the other prohibiting allmergers, as well as even proposals for breaking up very large firms,which in some cases have attained economic strength and influencecomparable to that of some nations. In Sweden, the existence and rationale for merger control has become widely known to the public in recentyears after three proposed mergers were abandoned on the grounds ofsevere restrictions on competition. Two of the mergers were examinedby the European Commission and one by the Swedish Competition Authority. The need for merger control is widely supported – but the specificprinciples and tools by which it should be exercised are subject to discussion and debate, and also revision.