Merger control shapes the timetable and structure of any significant technology deal. The Competition and Markets Authority can review a transaction that meets the tests in the Enterprise Act 2002, and the Digital Markets, Competition and Consumers Act 2024 has widened those tests and added a mandatory reporting duty for the largest digital firms. For an acquirer or a target in the digital sector, the first questions are whether the deal is caught, by which route, and how CMA review runs alongside national security screening. We advise on all three.

The regulatory framework

UK merger control is voluntary and non-suspensory for most parties: there is no obligation to notify, but the CMA can review a qualifying merger before or after completion. A merger qualifies for review where it gives rise to a relevant merger situation under the Enterprise Act 2002, and the CMA then assesses whether it results, or may be expected to result, in a substantial lessening of competition (section 22). That substantial lessening of competition test is unchanged for digital deals; what changed on 1 January 2025 was the jurisdictional thresholds that bring a deal within reach.

The Digital Markets, Competition and Consumers Act 2024 amended the jurisdictional tests in section 23 of the Enterprise Act. The target-turnover threshold rose to £100 million, the long-standing 25% share-of-supply test was retained, and a new acquirer-focused test was added, catching a deal where the acquirer already holds at least a 33% share of supply and more than £350 million of UK turnover. A small-merger safe harbour exempts deals where each party’s UK turnover is below £10 million. The acquirer test is aimed squarely at acquisitions by large digital incumbents of businesses that may have little turnover of their own.

Does my deal need CMA clearance?

A digital or technology transaction can fall within CMA jurisdiction by any one of three routes. The table below sets them out. Because market definition in digital infrastructure can be local rather than national, the share-of-supply tests can be met even where a national share looks modest, so the analysis has to map real overlaps rather than headline figures.

Route to jurisdiction	Test	Introduced or amended by
Target turnover	Target UK turnover above £100 million	Raised from £70 million by the DMCC Act 2024
Share of supply	Combined 25% share of supply in a UK market	Enterprise Act 2002 (unchanged)
Acquirer foothold	Acquirer holds 33% share of supply and more than £350 million UK turnover	New test under the DMCC Act 2024
Safe harbour	No foothold jurisdiction where each party’s UK turnover is below £10 million	New under the DMCC Act 2024

What extra rules apply to firms with strategic market status?

A firm designated with strategic market status under Part 1 of the DMCC Act faces a mandatory, pre-completion reporting duty that ordinary acquirers do not. Under section 57, a designated firm must report an acquisition of a 15% or greater shareholding in a UK-connected body corporate, or the formation of a joint venture, where the consideration is at least £25 million, before it completes. A short suspensory period follows the CMA’s acceptance of the report (section 63). This is a genuine standstill obligation, unlike the voluntary regime that applies to everyone else, and it needs to be built into the deal timetable from the outset for any transaction involving a designated party.

Why merger control matters for your deal

Merger review drives deal certainty and timing. A voluntary regime does not mean a safe one: the CMA can call in a completed deal and, in the meantime, impose an initial enforcement order that freezes integration. Parties near the thresholds routinely manage that risk through pre-notification discussions, and can now request a fast-track reference straight to a Phase 2 investigation where significant issues are likely, avoiding a Phase 1 clearance step. Merger review also runs in parallel with, and separately from, national security screening under the National Security and Investment Act 2021, which imposes its own mandatory notification in sensitive sectors including communications and data infrastructure. Clearance under one regime cannot be assumed from the other. Reading the competition and national security positions together, early, is what keeps a digital-sector deal on track.

How we work

We work with clients in three ways: as direct legal advisers on a specific question, as specialist co-counsel alongside a corporate team, and as fractional general counsel on a retained basis. Rob Bratby currently holds four fractional General Counsel appointments, at The One Touch Switching Company, TelXL, Core Communication and the UK Payments Initiative, giving direct insight into how regulated businesses are bought, sold and integrated. On a transaction, we read the deal and the regulation together, so competition and national security clearances are handled as part of the deal rather than discovered late in it. This work connects closely with our transactions practice.

Frequently asked questions about merger control in digital markets

Do I have to notify the CMA before completing a deal?

For most parties, no. UK merger control is voluntary, so there is no general obligation to notify and no automatic standstill. But the CMA can review a qualifying deal after completion and freeze integration while it does, so parties near the thresholds usually notify or hold pre-notification discussions to secure certainty.

What is the new acquirer-foothold threshold?

It is a jurisdictional route added by the DMCC Act 2024. The CMA can review a deal where the acquirer already holds at least a 33% share of supply in a UK market and has more than £350 million of UK turnover, even if the target is small. It is aimed at acquisitions of nascent competitors by large incumbents, subject to a safe harbour where each party’s UK turnover is below £10 million.

What extra obligations apply if a party has strategic market status?

A designated firm must report, before completion, any acquisition of a 15% or greater shareholding in a UK-connected company where the consideration is at least £25 million, with a short suspensory period after the CMA accepts the report. This mandatory, pre-completion duty is quite different from the voluntary regime that applies to other acquirers.

How does CMA review interact with national security screening?

They are separate regimes with separate triggers and timetables. The National Security and Investment Act 2021 imposes mandatory notification in sensitive sectors, including communications and data infrastructure, and clearance under it cannot be inferred from CMA clearance. A digital-sector deal can require both, and both need to be planned into the timetable.

Also see

Explore our related Digital Regulation pages on SMS Designation and Conduct Requirements, Market Investigations and Studies, Concurrent Competition Powers and Competition Enforcement and Litigation, or return to the Digital Regulation hub. This work connects with our Transactions, Telecoms Regulation and Payments Regulation practices. For commentary on current developments, see our Insights.