Substantial Group is a UK-based telecommunications infrastructure company focused on developing and operating full-fibre broadband networks. Founded in 2019, the company has rapidly grown into one of the country’s leading alternative network providers (altnets), challenging traditional operators in the UK broadband market. The group is backed by major investors, including Advencap, DigitalBridge, and Soho Square Capital, which together have supported the company with more than £1.6 billion in equity and debt financing to expand fibre infrastructure across the United Kingdom. 

The company operates primarily through its wholesale fibre infrastructure platform Netomnia, which builds and manages high-capacity fibre-to-the-premises (FTTP) networks delivering gigabit-speed broadband connectivity to homes and businesses. Through Netomnia’s infrastructure and its retail internet brands such as YouFibre and Brsk, Substantial Group provides ultrafast broadband services across numerous UK cities and towns. The group’s network had reached around 3 million premises and hundreds of thousands of customers, with expansion plans targeting up to 5 million premises by 2027 as demand for full-fibre connectivity continues to grow.

Substantial Group plays an important role in increasing competition in the UK broadband market by offering an alternative to the incumbent infrastructure provider Openreach. By deploying large-scale fibre infrastructure and supporting retail broadband providers, the company aims to accelerate the rollout of next-generation digital connectivity across the country. Its rapid growth and strategic importance in the fibre sector led to its acquisition in 2026 by nexfibre, a joint venture backed by InfraVia Capital Partners, Liberty Global, and Telefónica, for approximately £2 billion.