UK fibre-network deal enters deeper competition inquiry
The United Kingdom’s Competition and Markets Authority has moved nexfibre’s proposed acquisition of Substantial into an in-depth competition inquiry, with newly published responses from CityFibre and Sky sharpening the central question: would greater scale create a stronger rival to BT/Openreach, or would the deal remove an independent source of broadband competition?
The CMA referred the anticipated transaction to Phase 2 on July 1, 2026, after the parties requested the fast-track procedure. That process allowed the authority to move directly to an in-depth inquiry without completing the usual Phase 1 route; it was not an approval of the transaction. The deal has not been approved or blocked, and the statutory Phase 2 deadline is December 15, 2026.
What the proposed deal would combine
nexfibre is a joint venture owned by Liberty Global, Telefónica and InfraVia. The proposed acquisition covers Substantial and its subsidiaries Netomnia, Brsk, Brsk ISP and YouFibre.
Netomnia and Brsk develop and operate fibre-to-the-premises networks. YouFibre and Brsk ISP provide retail broadband services. nexfibre is a wholesale-only fibre provider, while Liberty Global and Telefónica are also joint owners of Virgin Media O2, a vertically integrated telecommunications company.
The proposed transaction would therefore bring together network assets, wholesale access and retail broadband operations. That structure is central to the CMA’s analysis because the businesses may compete both to supply network access to internet service providers and to sell broadband directly to households and businesses.
What changed this week
The CMA’s case page was updated on August 5, 2026, to publish CityFibre’s response to the authority’s July 7 areas-of-focus document. Sky’s response was published August 3.
Those submissions do not decide the case. They show how a competing network operator and a major independent wholesale broadband customer are framing the risks the CMA will investigate after the July 1 referral.
What the CMA is testing
The CMA’s July 7 document sets out the initial scope and theories of harm for the Phase 2 inquiry. It is a procedural document, not a finding that the transaction would harm competition.
Under the statutory test, the authority must assess whether the proposed merger could create a relevant merger situation and may be expected to result in a substantial lessening of competition in a UK market.
The CMA will first consider the likely competitive conditions without the transaction, known as the counterfactual. That includes the parties’ financial and operational positions, their likely future network investment and whether Substantial might otherwise remain independent or combine with another alternative-network provider.
Horizontal analysis asks whether the merger would remove a competitor that currently constrains the parties or might have done so in the future. The CMA said it will examine possible effects on prices, service quality, product range and innovation at both the wholesale and retail levels.
Vertical analysis concerns the relationship between network ownership and retail broadband. The authority will consider whether common ownership could change the incentives to supply independent internet service providers on competitive wholesale terms, and whether wholesale competition could affect retail competition indirectly.
The geographic question is also unresolved. The CMA will assess whether the relevant wholesale and retail markets are national or sub-national by examining provider footprints and whether prices or other terms vary with local competitive conditions.
The authority said it is not currently minded to focus on leased-line access. Its initial evidence indicates that Substantial sells limited volumes of those services and that third-party concerns in that area have not been significant.
The parties’ case for scale
The parties argue that combining the businesses would create a financially stronger wholesale challenger to BT/Openreach. Their case is that a larger platform could support more fibre investment, expand network reach and accelerate rollout.
The CMA’s areas-of-focus document records the parties’ claims that the transaction could unlock about £3.5 billion of investment and lead to stronger network competition. Those are projected benefits to be tested against evidence, not confirmed results.
The transaction also includes commercial arrangements under which nexfibre would finance and own upgrades to parts of Virgin Media O2’s broadband network, covering about 2.1 million premises, according to the CMA document. The arrangement is conditional on merger-control clearance.
Rivals and customers raise access concerns
CityFibre’s published response argues that, in areas where the relevant networks overlap, the transaction could reduce infrastructure competition from three providers to two. CityFibre says that could remove an alternative source of wholesale access for independent ISPs and weaken longer-term network competition.
Those are CityFibre’s submissions, not conclusions reached by the CMA. The authority has not published a final overlap analysis or decided that a substantial lessening of competition will occur.
Sky’s response focuses on the position of independent retail providers that depend on wholesale access from third-party networks. Sky says that around 80% of Netomnia’s footprint overlaps with Virgin Media O2’s; that figure appears in Sky’s submission and has not been presented as a CMA-verified finding.
Wholesale access matters because an independent ISP can use another company’s network rather than build its own. If access becomes less available or less attractive, retail providers could face higher costs, fewer network options or weaker negotiating leverage. The eventual effect on customers would depend on the CMA’s evidence and any remedies, not simply on the referral.
What it could mean for broadband customers
People in areas where the networks overlap could eventually see effects on provider choice, prices, promotional offers, speeds, service quality, innovation and future network investment. Businesses and independent ISPs could also be affected by the terms and availability of wholesale access.
But no consumer change follows automatically from the Phase 2 referral. The transaction remains proposed, and the CMA has not yet published a final finding, remedy package or decision on whether the deal should proceed.
What happens next
The inquiry group will gather further evidence from the parties, rivals, wholesale customers and other market participants. The CMA may clear the transaction, require remedies or prohibit it if it finds that the deal would substantially lessen competition and available remedies were inadequate.
The next major formal milestone is December 15, 2026, the statutory Phase 2 deadline. Until then, the central unresolved issue is whether consolidation would give the UK a stronger alternative to BT/Openreach or remove an independent competitor that could otherwise increase wholesale and retail choice.
Sources
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