UK Regulator Adopts More Favorable Merger Efficiencies Guidance
The UK's Competition and Markets Authority has published revised guidance on merger efficiencies, signaling a greater openness to such arguments from merging parties and potentially easing the path for deal approvals.
On September 3, 2026, the UK's Competition and Markets Authority (CMA) published final revised guidance on its assessment of merger efficiencies. The new guidance signals a significant shift toward greater openness to efficiency-based arguments from merging parties, a development driven by a government mandate to promote economic growth. While the core analytical framework remains, the revisions create a more favorable environment for deal-making by expanding on the types of efficiencies the CMA will consider, allowing more flexibility on the timeline for their realization, and clarifying evidentiary standards. The guidance notably states that the CMA will accept evidence generated after a merger is contemplated and assures parties that submitting an efficiencies defense does not concede the existence of a substantial lessening of competition. For sophisticated counsel, this marks a critical change in regulatory posture. Companies and their advisors should consider preparing and presenting efficiency claims earlier in the UK merger review process and explore the newly clarified role of behavioral remedies in securing efficiency-related benefits to overcome potential competition concerns.