UK Merger Control & National Security: Year In Review & Outlook
September 15, 2026
Merger Control
The past year confirmed a UK merger regime recalibrated for growth. Following the Government steer and a change of leadership at the CMA in the first half of 2025, the agency pressed ahead with its ‘4Ps’ programme, embedding improvements to pace, predictability, proportionality and process across its work.
Formal investigations became more targeted. In the past year to 31 August 2026, the number of Phase 1 investigations fell by 17% and their timelines shortened. Where concerns arose, the CMA showed greater openness to behavioural and hybrid remedies.
There were several policy changes, including the CMA’s revised guidance on jurisdiction and procedure, revised guidance on remedies, revised guidance
on assessing merger efficiencies, and a Government consultation on ‘Refining Our Competition Regime’, which included a proposal to replace independent Phase 2 panels with CMA Board sub-committees.
National Security
The number of transactions caught by the National Security and Investment Act 2021 (NSIA) continues to increase. In the past year to 31 March 2026, around 1,300 filings were submitted, up by 15% from the previous year. For most transactions the process remains straightforward, with more than 95% of notified acquisitions cleared after an initial screening process that typically takes around 8-9 weeks after filing. Of the 60 transactions called in for full review, eight resulted in behavioural remedies and only one was blocked. Enforcement continues to focus primarily on investment from China, though acquisitions of sensitive targets by US and EU investors have also been subject to remedies.
The Government has emphasised that the NSIA is designed to “support global investment into the UK while safeguarding the most sensitive areas of the economy in a secure, predictable and proportionate way.” It has also announced reforms aimed at updating the scope of the mandatory notification regime and reducing unnecessary filing burdens (including for internal reorganisations).