Conduct on the part of two or more parties which falls short of an agreement or decision for either the purpose of the prohibition in Article 101(1) of the Treaty on the Functioning of the European Union (TFEU), or the Chapter I prohibition in the UK Competition Act 1998, but which consists of some form of direct or indirect, and often informal, contact or co-operation between competitors.

For further details, see Practice notes, Cartels: EC law and practice and Cartels: UK law and practice.