The UK’s Competition and Markets Authority (CMA) has officially outlined its specific investigation boundaries for the full-scale probe into Nexfibre’s planned acquisition of Substantial Topco. The multi-billion-dollar deal seeks to integrate Substantial’s independent full-fiber broadband networks, Netomnia and Brsk, directly under the Nexfibre umbrella.
Nexfibre operates as a wholesale fiber provider alongside its anchor tenant, Virgin Media O2 (VMO2). Both networks share parent ownership under global telecom giants Liberty Global and Telefónica, alongside infrastructure investor InfraVia Capital Partners. Because the involved parties proactively requested a fast-track reference, the deal bypassed a traditional preliminary evaluation and moved directly into an in-depth review on July 1, 2026.
The regulatory body’s newly issued framework highlights exactly where it believes competition could be diminished. The independent Inquiry Group is centering its scrutiny on potential horizontal unilateral effects across both the retail and wholesale broadband sectors. Regulators are evaluating whether removing a major independent network competitor will grant the merged business excessive power to raise subscriber pricing, compromise overall service quality, or stall long-term infrastructure innovation without any market pressure.
The CMA will look closely at localized sub-national footprints to determine if pricing power is heavily dictated by regional network overlaps rather than a single national market. Additionally, the regulator is evaluating the vertical integration dynamics between the companies. The investigation will dissect whether VMO2’s vast consumer retail presence might create negative incentives for Nexfibre, potentially discouraging them from offering fair wholesale pricing and network access to rival internet service providers. High-capacity business leased lines will be omitted from heavy tracking, as early evidence indicates the merging networks hold minimal market share in that specific corporate sector.
The companies argue the merger will unlock massive operational efficiencies and scale economies, transforming the combined platform into a robust infrastructure challenger capable of going toe-to-toe with the dominant BT and Openreach network. They contend these structural cost savings will ultimately benefit everyday consumers through cheaper monthly bills and accelerated migrations from legacy cable systems to fiber. Working alongside telecom authority Ofcom, the CMA has opened the floor for industry feedback, requiring non-confidential evidence to be submitted before a critical mid-July deadline.
