The Competition and Markets Authority has provisionally concluded that nexfibre’s planned takeover of rival broadband builder Substantial could weaken competition in the UK’s wholesale fixed broadband market, according to an interim report published on 2 October 2026.
nexfibre is a joint venture between Liberty Global, Telefónica and InfraVia. Substantial is the parent company behind Netomnia, Brsk, Brsk ISP and YouFibre, four names familiar to households in areas served by alternative full-fibre networks outside the BT Openreach and Virgin Media footprint.
What the CMA found
The regulator opened an in-depth Phase 2 investigation after referring the deal on 1 July 2026. Its interim report, running to 1.4MB with a separate appendices and glossary document, sets out provisional competition concerns specifically in the wholesale supply of fixed broadband services, the market where altnets sell network access to retail internet providers.
The CMA has not published its final findings. The interim report is a staging post, and the regulator is inviting responses to it until 5pm on Friday 23 October 2026. A separate notice summarising the report in plainer terms has also been released.
Industry has already had its say
Before the interim report landed, the CMA had gathered formal responses to its earlier “Areas of focus” document, which set out the inquiry’s initial scope without reaching conclusions. BT Group, CityFibre, Grain Connect, Hyperoptic and Sky all submitted responses between late July and early August 2026, alongside a joint response from the merging parties themselves. These filings give a sense of how seriously the UK’s established and challenger broadband providers are taking the deal’s potential to reshape the wholesale market.
Separately, on 17 July 2026 the CMA accepted interim undertakings from Substantial under section 80 of the Enterprise Act 2002, a legal mechanism used to prevent pre-emptive action, such as restructuring, that could undermine any eventual remedy.
What happens next
Having identified concerns, the CMA has now moved to the remedies stage. On 20 October 2026 it published an invitation to comment on the possible actions it might take to address the substantial lessening of competition identified in its interim report. The deadline for comments on remedies is 5pm on Tuesday 27 October 2026, a tight week-long window for stakeholders to respond.
The inquiry group overseeing the case comprises chair Cyrus Mehta, Robin Cohen, Ashleye Gunn and Crispin Wright. The CMA’s statutory deadline to conclude the whole Phase 2 process is 15 December 2026.
Why it matters for UK broadband users
If the deal consolidates several well-known full-fibre altnet brands under one owner, it could affect pricing and choice in the wholesale market that underpins retail broadband deals in parts of the UK. Any remedies the CMA eventually imposes, whether structural changes or behavioural commitments, will shape how nexfibre and Substantial can operate together, if the deal proceeds at all.
What to watch next: whether the CMA’s final report, due by 15 December 2026, confirms the provisional findings and what remedies it settles on, and whether BT Group, CityFibre, Hyperoptic, Sky or other altnets push back further during the short remedies consultation window closing on 27 October.