UK antitrust investigations and appeals

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The Competition and Markets Authority (CMA) investigates allegations of anti-competitive behaviour that have an impact in the UK (breaches of Chapter I and/or Chapter II of the Competition Act 1998). Investigations are carried out under the Competition Act 1998 (CA 1998).

Investigations can start in one of four ways:

  1. •

    a company involved in wrongdoing blowing the whistle

  2. •

    an individual involved in wrongdoing blowing the whistle

  3. •

    a complaint from a third party, or

  4. •

    the CMA receiving general market intelligence suggesting a breach of competition law.

If an investigation is launched, it will follow a set process. Investigations can take several years to complete.

If the CMA finds that competition law has been breached, it can impose severe penalties on undertakings, including large fines.

If a potential investigation involves a regulated sector where the sectoral regulator has concurrent competition powers, an investigation may be carried out by either the sectoral regulator or the CMA (see below).

For a review of the investigation process, see CMA behavioural investigation process. For a flowchart setting out the different stages of

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Latest Competition News

UK Competition law—daily round-up (19/09/2025)

A round-up of UK competition law developments, including (amongst other things) the CMA issues final report in remittal of Spreadex/Sporting Index merger.

EU Competition law—daily round-up (19/09/2025)

A round-up of EU competition law developments, including the latest EUMR developments.

EU Competition law—daily round-up (18/09/2025)

A round-up of EU competition law developments, including (amongst other things) the latest EUMR developments.

Competition weekly highlights—18 September 2025

This week's edition of Competition weekly highlights includes, from a UK perspective: (1) the CMA publishing papers on competition policy and the UK's industrial policy, (2) the CAT publishing a guidance note on filing deadlines, and (3) the Government publishing the Competition Appeal Tribunal (Amendment) Rules 2025. This week's highlights also includes, from an EU perspective: (1) the Commission launching a consultation on draft revised TTBER and Guidelines, (2) the Commission accepting commitments offered by Microsoft in relation to abusive tying of Teams, and (3) a Court of Justice's judgment setting aside the General Court's judgment and annulling the Commission's decision to approve State aid for Hungary's Paks II nuclear power station.

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