E.ON Next Completes Ovo Energy Takeover: What the ‘Big Three’ Energy Market Means for Households

The UK household energy market took another step towards consolidation on Thursday, 8 October 2026, when E.ON Next completed its purchase of Ovo Energy. The deal was cleared by Britain’s competition watchdog, but the clearance did not silence concerns that a market once celebrated for its crowd of challenger brands is becoming a place where a handful of large players set the terms. Almost three-quarters of households in Great Britain are now served by just three suppliers.

This guide explains what happened, what the numbers show, why the “Big Six becomes Big Three” framing is attracting so much attention, and what it means for customers, for the suppliers and for regulators. It is written for readers who want the context behind the headline, not just the headline itself.

What Happened: The Deal in Brief

E.ON Next, the retail arm of E.ON UK, already supplied around 5.6 million households. With the acquisition of Ovo Energy, which serves about 4 million households, it will hold roughly 25% of the household energy market, equivalent to 13.45 million gas and electricity accounts. That makes it Great Britain’s second-largest energy supplier, narrowly behind Octopus Energy, which holds around 26% of the market, or 14.3 million accounts.

British Gas, once the undisputed leader of the market, now sits third with about 23% of the market, or 12.5 million accounts. Put together, the three largest suppliers serve close to three-quarters of households. When EDF Energy and Scottish Power are added, about 90% of Great Britain’s household supply market is held by only five companies.

For Ovo’s customers, the immediate message is continuity. There will be no immediate change to their tariffs, accounts or service as a result of the completion. Over the longer term, integration decisions on billing systems, customer service and branding will determine whether customers notice any difference.

Key Numbers at a Glance

• E.ON Next before the deal: about 5.6 million households.
• Ovo Energy: about 4 million households.
• Combined E.ON Next: about 25% of the market, or 13.45 million accounts.
• Octopus Energy: about 26% of the market, or 14.3 million accounts.
• British Gas: about 23% of the market, or 12.5 million accounts.
• Top five suppliers combined: about 90% of household supply.

These figures come from reporting by The Guardian on the completion of the deal. Market share numbers are usually expressed in accounts, and because many households hold separate gas and electricity accounts, they should be read as shares of accounts rather than shares of homes.

From Big Six to Big Three: How the Market Got Here

To understand why this deal matters, it helps to go back a decade. In 2016, the so-called “Big Six” suppliers (British Gas, EDF Energy, E.ON UK, SSE, Scottish Power and npower) dominated roughly 85% of the market. That year, a landmark investigation by the Competition and Markets Authority (CMA) warned that customers were overpaying by roughly £1.4 billion to £1.7 billion every year because of weak competition.

The policy response, over the following years, was to encourage new entrants. A wave of start-ups arrived, led by Octopus, Ovo and Bulb Energy. For a while, the strategy appeared to work: customers had more choice, more innovative tariffs and better-rated customer service from the challengers than from the incumbents.

Then the market began to shrink again. SSE sold its household supply business to Ovo in 2019, giving the challenger a large base of customers overnight. During the 2021/22 energy crisis, dozens of suppliers went bust as wholesale prices soared and fixed-price tariffs became loss-making. Bulb Energy became the biggest casualty when it entered administration in 2022, and Octopus took on around 1.5 million of its customers, which helped it become the biggest supplier in the market.

About 30 firms dropped out of the market in total. The result is the structure we see today: a market where the biggest names are a mix of an ambitious former challenger (Octopus), a European utility’s UK arm (E.ON Next), and the legacy incumbent (British Gas), with EDF and Scottish Power making up the rest of the top five.

Why the Watchdog Cleared It

The competition watchdog cleared the takeover, but reporting on the decision makes clear it did so despite concerns that fewer suppliers could reduce the incentive to lower bills and reduce the choice available to customers. Clearance does not mean the concerns disappeared; it means the regulator concluded that the deal did not cross the legal threshold for blocking it.

There are several reasons regulators may reach that conclusion in a market like this one. First, the retail energy market has a price cap that limits what suppliers can charge on standard variable tariffs, which weakens the argument that a larger supplier could simply raise prices. Second, suppliers buy energy on wholesale markets whose prices they do not control. Third, the alternative to a deal in some circumstances is not a more competitive market but a weaker supplier, or one that exits altogether, after the experience of 2021/22.

That last point is not abstract. The cost of supplier failure is real and is ultimately socialised across bill payers. A larger, better-capitalised supplier is less likely to collapse, and that has value of its own.

The Competition Concern: “Three Versions of the Same Thing”

Tom Goswell, the energy supply lead at the consultancy Cornwall Insight, captured the tension in his response to the deal: “The big six have become the big three, and there have been questions raised over how this will impact household choice and the health of the market.”

He also acknowledged the other side of the argument: “Larger suppliers do bring with them a degree of stability, and after about 30 firms dropped out of the market, leaving customers wondering who would be sending their next bill, stability is not something to dismiss lightly.”

His central worry is about incentives. As he put it, the concern with fewer suppliers is that “the pressure to compete eases off, taking with it some of the incentive to keep prices low and offer something different.” The test over the next few years, he said, will be whether households who shop around “find a genuine range of deals waiting for them rather than three versions of the same thing.”

That is a useful way to frame the question. The market does not need dozens of suppliers to be competitive. What it needs is suppliers that differ meaningfully in price, product and service, and customers who feel able to switch between them.

E.ON’s Response

Chris Norbury, chief executive of E.ON UK, rejected the idea that the market lacks competition. He described it as “fiercely competitive” and said the company’s “flexibility and scale” would allow it to “deliver for customers now and to transform for the energy system to come.”

The phrase “the energy system to come” points to the strategic logic behind the deal. Suppliers are no longer just sellers of gas and electricity. They are increasingly competing to sell smart meters, time-of-use tariffs, electric vehicle charging, heat pumps, solar panels and home batteries. Those products require investment in technology and customer data, and scale helps pay for them. A supplier with 13 million accounts has a stronger base on which to build those services than one with 4 million.

What It Means for Customers

If you are an Ovo customer

You do not need to do anything. Your existing tariff, direct debit and online account continue as normal. Watch for communications over the coming months about any changes to branding, apps or customer service channels, and keep an eye on the end date of any fixed-term deal you hold.

If you are a customer of another supplier

The practical advice is the same as it has always been: compare the market regularly. Even with fewer suppliers, there remain meaningful differences between tariffs, particularly between fixed and variable deals and between suppliers who offer smart-tariff discounts. The Big Three plus EDF and Scottish Power are joined by a long tail of smaller suppliers that can still be competitive for particular customer types.

If you are on a smart or time-of-use tariff

This is where scale could help customers. The ability to shift demand to cheaper hours relies on suppliers being able to forecast and manage large volumes of consumption. Bigger suppliers may be better placed to invest in those systems, though the benefits only reach customers if competitive pressure forces suppliers to pass them on.

The Wider Context: Energy Costs Are Back in Focus

The timing of the deal is notable. Energy and fuel costs are already under pressure. Reporting this week describes oil prices jumping more than 5% to around $105 a barrel amid Middle East tensions and a hurricane threat off the US coast, with diesel at UK pumps reaching £2 a litre last week. Those pressures feed into wholesale energy costs, inflation and, ultimately, household bills.

In that environment, any suggestion that competition is weakening is politically sensitive. Governments across the political spectrum have been under pressure to show they are protecting households from price shocks, and a consolidating supplier market gives critics a ready-made argument that bill payers are more exposed than they should be.

What Regulators and Policymakers May Watch Next

• Switching rates: if fewer customers switch, the competitive discipline on pricing weakens.
• Tariff diversity: do suppliers continue to offer meaningfully different products, or do offers converge?
• Financial resilience: the regulator, Ofgem, has tightened capital requirements for suppliers since the 2021/22 failures, and larger balance sheets are part of the stability argument.
• Customer service standards: integrations of this scale can disrupt billing and support, and complaints data will show whether that happens.
• New entrants: whether the market remains open enough for new challengers to emerge.

Lessons for Business and Governance Readers

For readers following corporate governance and mergers, the deal illustrates several recurring themes.

Merger clearance is a legal test, not a verdict on market health. A transaction can be lawful and still alter the competitive dynamics of an industry in ways regulators will continue to monitor.

Market structure follows market shocks. The proliferation of challengers after 2016 and the consolidation after 2021/22 show how external shocks reshape industries, and how policy designed for one environment can look different in another.

Scale and competition can pull in opposite directions. The same factors that make a supplier stable, such as a large customer base and strong balance sheet, can reduce the intensity of rivalry. Boards weighing acquisitions should expect scrutiny on both sides of that trade-off.

Integration is where value is won or lost. Customers will judge the combined business on whether bills, apps and support work smoothly, not on the strategic rationale.

Frequently Asked Questions

Who is now the biggest energy supplier in Great Britain?

Octopus Energy remains the largest, with about 26% of the household market, narrowly ahead of the enlarged E.ON Next at about 25% and British Gas at about 23%.

Will my Ovo tariff or price change?

No immediate changes have been announced for Ovo’s 4 million households. Prices for most customers are also shaped by the regulated price cap and by the terms of any fixed deal you already hold.

Why did the watchdog allow the deal?

The competition watchdog cleared the takeover while acknowledging concerns about reduced choice and incentives. Clearance means the deal did not meet the threshold for being blocked, not that the concerns were dismissed.

Is the energy market less competitive than before?

Concentration is higher than it was a few years ago, with about 90% of household supply held by five companies. Whether competition is weaker depends on whether prices, products and switching behaviour show it. Analysts say the next few years will be the test.

The Bottom Line

E.ON Next’s completion of its Ovo Energy takeover reshapes the top of the Great Britain household energy market and closes another chapter in the story of the post-2016 challenger boom. Supporters of the deal point to stability, scale and the investment needed for the energy transition. Critics point to a market where three suppliers serve nearly three-quarters of homes and where the incentive to cut prices may be weaker.

Both views can be true at once, which is why the aftermath matters more than the announcement. Customers can protect themselves by comparing tariffs regularly, and regulators will be watching whether the market delivers the real choice its defenders promise. As oil and fuel prices stay elevated, the spotlight on how well this market serves households is only going to get brighter.

Sources: reporting from The Guardian (8 October 2026) on the completion of the E.ON Next and Ovo Energy deal, including comments from Cornwall Insight and E.ON UK.