Oligopoly meaning

In legal practice, oligopoly describes a market in which a small number of suppliers or sellers account for most sales, so each firm’s pricing and output decisions are interdependent and competitive pressure is limited. It is an economic, descriptive term rather than a defined concept in UK or Irish legislation or case law, although competition authorities and courts use it when assessing market power, merger control and market investigations. Typical indicators are high concentration, barriers to entry or expansion, transparency that enables parallel conduct, similar products, and repeated interactions that can facilitate tacit coordination. An oligopoly does not, by itself, establish illegality or dominance, but it can support findings of collective dominance or raise risks of coordinated effects in mergers; explicit collusion (cartels) remains prohibited. In the UK, the CMA applies these concepts under the Competition Act 1998 and the Enterprise Act 2002. In Ireland, the CCPC and the courts apply analogous principles under the Competition Act 2002, informed by EU competition law. Usage and legal significance are broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland.