The deal, announced on 11 May 2026, would bring together E.ON's existing 5.5 million UK accounts, served through its E.ON Next brand, with Ovo's roughly 4.1 million customers. The resulting entity would supply approximately 9.6 million households, surpassing Octopus Energy, which currently serves nearly 8 million UK homes, as reported by the Guardian. Completion remains subject to regulatory approval.

For finance directors and operators at UK SMEs, the implications extend well beyond the domestic retail market. A supplier of this scale could alter pricing dynamics, reshape switching patterns, and influence the competitive behaviour of every remaining player in business energy procurement.

What the deal involves

E.ON, listed on the Frankfurt Stock Exchange (XETRA: EOAN), operates in the UK through its E.ON Next retail brand. The division currently serves approximately 5.5 million residential and business accounts, making it one of the country's largest suppliers but still trailing both Octopus Energy and British Gas, the retail arm of Centrica (LSE: CNA).

By absorbing Ovo's customer book, E.ON would vault to the top of the league table. The combined 9.6 million customer figure, cited by the Guardian, would place the merged group comfortably ahead of Octopus and re-establish a clear market leader in UK retail energy for the first time since the old Big Six structure began fragmenting.

Financial terms of the acquisition have not been publicly disclosed. The Guardian described Ovo as "struggling" at the point of sale, suggesting E.ON may have secured favourable pricing relative to the book's nominal value.

Why Ovo was vulnerable

Ovo Energy's trajectory since its landmark 2020 acquisition of SSE Energy Services illustrates the risks of rapid scale without matching financial resilience. That deal, reportedly valued at approximately £500 million, catapulted Ovo from a mid-sized challenger into one of Britain's largest suppliers almost overnight, adding roughly 3.5 million customer accounts.

The integration proved costly. Ovo faced significant operational challenges in migrating SSE customers onto its own platform, and the energy price crisis of 2021 to 2023, driven by wholesale gas volatility following Russia's invasion of Ukraine, placed enormous strain on supplier balance sheets across the sector. Ovo reported substantial losses during this period and carried elevated debt levels relative to its revenue base.

The company undertook rounds of cost-cutting and workforce reductions as it sought to stabilise its finances. Despite these efforts, Ovo's position remained precarious. The combination of legacy integration costs, accumulated losses, and a competitive market in which well-capitalised rivals such as Octopus continued to grow made an independent path increasingly difficult.

Ovo's founder, Stephen Fitzpatrick, built the company from a small Bristol-based challenger into one of the UK's most prominent energy brands. The sale to E.ON marks the end of that independent chapter.

What regulators will scrutinise

The deal will almost certainly face a detailed review by the Competition and Markets Authority (CMA). A merger of this size in a sector as politically sensitive as household energy is unlikely to pass without a Phase 1 investigation at minimum, and a Phase 2 referral remains plausible.

The CMA will assess whether the combined entity's market share could lead to a substantial lessening of competition. With E.ON-Ovo at 9.6 million customers, Octopus at roughly 8 million, and Centrica's British Gas serving a comparable base, the UK retail energy market would effectively consolidate around three dominant suppliers. That structure would bear a resemblance to the old Big Six era, albeit with fewer players and a different cast.

Ofgem, the energy regulator, will also have a role. While Ofgem does not directly approve mergers, it sets the regulatory framework within which suppliers operate, including the price cap mechanism that governs default tariff rates for domestic customers. A more concentrated market could prompt Ofgem to reconsider its approach to competition thresholds and supplier obligations.

The timeline for CMA review is uncertain. Phase 1 investigations typically take around 40 working days from the point of referral, according to CMA guidance. If the authority identifies concerns, a Phase 2 investigation could extend the process by several months. E.ON and Ovo will likely need to demonstrate that the merger does not reduce consumer choice or raise barriers for smaller suppliers seeking to compete.

Smaller energy companies and consumer groups may raise objections. The consolidation of nearly 10 million accounts under a single brand could make it harder for independent suppliers to achieve the scale necessary to negotiate competitive wholesale contracts, potentially widening the gap between large and small players.

What this means for business energy buyers

The domestic retail market and the business energy market are distinct but interconnected. A supplier with 9.6 million household accounts commands significant purchasing power in wholesale markets, and that scale advantage can flow through to its commercial energy division.

For SMEs negotiating business energy contracts, the emergence of a dominant E.ON-Ovo entity presents a mixed picture.

On one hand, greater scale can drive operational efficiencies. A larger supplier may be able to offer more competitive fixed-rate contracts, invest more heavily in digital account management, and absorb wholesale price shocks more effectively than a smaller rival. E.ON's backing by its German parent company, one of Europe's largest energy groups, adds financial depth that Ovo lacked as an independent.

On the other hand, reduced competition at the top of the market could erode the incentive to compete aggressively on price and service. The period following the collapse of dozens of smaller suppliers during the 2021-2022 energy crisis already narrowed the field. If the market settles into a Big Three structure, business energy brokers may find fewer genuinely differentiated offers to put before their clients.

Switching dynamics

Ofgem data has consistently shown that switching rates among both domestic and business customers tend to be higher when the market is more fragmented. A consolidated market with three large players and a long tail of small challengers may reduce the practical choices available, particularly for SMEs outside major urban centres where broker coverage is thinner.

Operators and finance directors should monitor the CMA's review closely. The conditions attached to any approval, such as requirements to divest certain customer books or maintain service commitments, could materially shape the competitive landscape for business energy over the next two to three years.

The broader pattern

This deal fits a wider pattern of consolidation in UK utilities. The retail energy market has contracted sharply from the peak of more than 70 licensed suppliers in the late 2010s to a much smaller field today. Each wave of consolidation has shifted bargaining power towards larger incumbents.

Whether that concentration ultimately benefits or harms business customers depends on the regulatory framework that accompanies it. The CMA and Ofgem face a consequential decision: permit the creation of a clear market leader and trust that competition from Octopus and British Gas will discipline pricing, or intervene to preserve a broader competitive field. The outcome will shape UK energy procurement for years to come.