# Big Six energy suppliers

The Big Six were the United Kingdom's largest retail suppliers of gas and electricity, who dominated the market following liberalisation in the late 1990s. By 2002, six companies – British Gas, EDF Energy, E.ON, RWE npower, Scottish Power and SSE – had emerged from the 15 former incumbent monopoly suppliers (the 14 regional public electricity suppliers and British Gas).
In 2008, the Big Six still had over 99% of domestic and small business customers. They were vertically integrated in electricity, owning sufficient generation capacity to supply all their customers; while in gas, only Centrica (British Gas) owned production facilities. By the third quarter of 2019, after efforts by the regulator Ofgem to promote competition, their combined share in Great Britain was 70% for electricity supply and 69% for gas. The purchase of SSE's retail business in January 2020 by OVO Energy, a competitor founded in 2009, marked the end of the original Big Six.

## The companies

Source:
| Supplier | Parent | Other brands | Former brands (including retail/supply divisions of former regional electricity boards) |
| British Gas | Centrica | Scottish Gas | |
| EDF Energy | Électricité de France | | SEEBOARD, SWEB Energy, London Electricity |
| E.ON UK including npower | E.ON for npower RWE (from 2002) Innogy (from 2016) E.ON (from 2019) | | Northern Electric, Midlands Electricity, East Midlands Electricity, NORWEB, Powergen, Yorkshire Electricity |
| OVO Energy | | | Following purchase of SSE's retail business in 2020 |
| Scottish Power | Iberdrola (from 2007) | | MANWEB |
| SSE | | | Scottish and Southern, Southern Electric, SWALEC, Scottish Hydro |

## 2014–2016 competition investigation

In June 2014, energy market regulator Ofgem referred the energy industry to the Competition and Markets Authority (CMA). The authority investigated the "six large energy firms" and published its report in June 2016. For the retail market, the report recommended:
* Removal of the requirement imposed by the 2014 Retail Market Review that limited suppliers to offering no more than four tariffs
* Establishment by Ofgem of a database of customers who have been on a "standard variable tariff" for three years or more, which competitors could use to contact those customers
* A temporary price cap for customers on prepayment meters
* Measures to support price comparison websites in the energy market.

## Consolidation to Big Five

In 2017, SSE and Npower announced a merger of their retail businesses, but this was scrapped in 2018.
Just after the failed SSE-Npower merger in late 2018, it was reported that a consolidation to the Big Five would still occur, as Npower would be acquired by default by E.ON due to the already-planned asset swap by the respective German parents, Innogy and E.ON. This was completed in 2019.

## Alternatives to the Big Six

In December 2014, Utility Warehouse, part of FTSE 250-listed company Telecom Plus became the UK's biggest independent energy supplier through a £218m deal to buy 770,000 existing customers from npower. In September 2014, First Utility (since rebranded as Shell Energy) announced it was the first independent utility supplier to reach the milestone of 1m customer accounts for gas and electricity – the equivalent of 550,000 customers, which made it the seventh-largest energy supplier in the UK and the country's biggest independent energy provider. In June 2015, a Cornwall Report stated Opus Energy had broken the dominance of the 'Big Six' energy suppliers in the business market.
The Competition and Markets Authority published an investigation into the energy supply market in June 2016, following a referral by Ofgem in June 2014. The report identified 34 suppliers of both electricity and gas to households, and described the three largest suppliers outside the Big Six as "mid-tier suppliers"; these were First Utility, OVO Energy and Utility Warehouse. Other significant suppliers (each with more than around 1% market share) were Co-operative Energy, Extra Energy and Utilita Energy (specialising in pre-pay customers). The combined market share of suppliers outside the Big Six had increased from less than 1% in 2011 to around 13% in the first quarter of 2016.
Since 2009, other entrants into the market include a number of new energy companies including Bulb Energy, Good Energy, Ecotricity, and Octopus Energy. Many of these newer entrants are seeing significant growth in customer numbers, in part due to their greater commitment to renewable energy and, in the case of Co-op Energy, community renewable energy projects.
The energy regulator Ofgem maintains a list of all licensed electricity suppliers and distribution network operators.

### Local authority-owned companies

Three of the alternative energy companies have been owned by local authorities. The first such company since 1948 was Robin Hood Energy, owned by Nottingham City Council, which entered the market in 2015. Bristol Energy, also launched in 2015, was owned by Bristol City Council. Both Robin Hood Energy and Bristol Energy were available to consumers throughout the country until their demise in 2020.
In January 2020, London Power was launched by the Mayor of London. Contrary to the other two companies, it only provides gas and electricity to London homes. London Power is not itself an energy supplier, instead it is a partnership between the Greater London Authority and a providing partner, currently Octopus Energy.

### Defunct competitor companies
#### Before 2021

By January 2019, ten small energy suppliers had ceased trading or been taken over by others, and others followed similar paths until the market turbulence in the autumn of 2021.
2016 to 2020 :
| Company | Ceased trading | Customers (approx.) | Customers transferred to |
| Affect Energy | September 2018 | 22,000 | Octopus Energy (acquisition) |
| Breeze Energy | December 2019 | 18,000 | British Gas |
| Brilliant Energy | March 2019 | 17,000 | SSE |
| Bristol Energy | September 2020 | 155,000 domestic, 4,000 business | Business: Yü Energy Domestic: Together Energy |
| Economy Energy | January 2019 | 235,000 | OVO Energy |
| ENGIE UK | January 2020 | 70,000 | Octopus Energy (acquisition of ENGIE's domestic UK customers) |
| Eversmart Energy | September 2019 | 39,000 domestic | Utilita Energy Limited |
| Extra Energy | November 2018 | 108,000 domestic, 21,000 business | ScottishPower |
| Flow Energy | May 2018 | 130,000 | Co-op Energy (acquisition) Brand continued until acquired by Octopus in 2019 |
| Future Energy | January 2018 | 10,000 | Green Star Energy |
| GB Energy Supply | November 2016 | 160,000 | Co-op Energy (acquisition) Brand continued until acquired by Octopus in 2019 |
| Green Star Energy | October 2019 | 200,000 | Shell Energy (acquisition) Green Star was a subsidiary of Canada's Just Energy |
| Iresa | July 2018 | 100,000 | Octopus Energy |
| OneSelect | December 2018 | 36,000 | Together Energy |
| Our Power | January 2019 | 31,000 | Utilita Energy |
| Robin Hood Energy | September 2020 | 112,000 domestic, 2,600 business | British Gas |
| Solarplicity | August 2019 | 60,000 | EDF Energy |
| Spark Energy | November 2018 | 290,000 | OVO Energy |
| Tonik Energy | October 2020 | 130,000 | ScottishPower |
| Toto Energy | October 2019 | 134,000 | EDF Energy |
| Usio Energy | October 2018 | 7,000 | First Utility |
| Yorkshire Energy | December 2020 | 74,000 | ScottishPower |

#### 2021–2022

Sharp increases in wholesale gas prices in summer and autumn 2021, and a consequent increase in wholesale electricity prices, led to further collapses. High prices continued into 2022. Ofgem continued to arrange for customers of those companies to be transferred to other suppliers, but when Bulb Energy failed in November 2021 a different approach was needed: with 1.7 million customers, it was the seventh biggest supplier company. Bulb was placed in "special administration" and the UK government undertook to cover its losses while a sale or restructuring was organised, with a potential cost to taxpayers of £1.7 billion.
2021 onwards :
| Company | Ceased trading | Customers (approx.) | Customers transferred to |
| Zog Energy | 1 December 2021 | 11,700 | EDF Energy |
| Simplicity Energy | January 2021 | 50,000 | British Gas Evolve |
| Green Network Energy | January 2021 | 360,000 | EDF |
| Ampoweruk Ltd | 2 November 2021, finalised 3 November | 600 or 2,600 | Yü Energy |
| Omni Energy | 3 November 2021 | under 10,000 | Utilita |
| MA Energy | 3 November 2021 | under 10,000 | SmartestEnergy Business Limited |
| Neon Reef | 16 November 2021 | 30,000 | British Gas |
| Social Energy Supply | 16 November 2021 | 5,500 | (TBA) |
| CNG-Power | 3 November 2021 | under 10,000 | (TBA) |
| Zebra Energy | 3 November 2021 | under 10,000 | (TBA) |
| Bluegreen | 1 November 2021, finalised 3 November | 5,600 | British Gas |
| Avro Energy | 22 September 2021 | 580,000 | Octopus Energy |
| Colorado Energy | 13 October 2021 | 15,000 | Shell Energy |
| Daligas | 14 October 2021 | 9,000 | Shell Energy |
| ENSTROGA | 29 September 2021 | 6,000 | E.ON Next |
| Green Supplier Limited | 22 September 2021 | 255,000 | Shell Energy |
| GOTO Energy | 18 October 2021 | 22,000 | Shell Energy |
| Hub Energy | 9 August 2021 | 6,000 domestic, 9,000 others | E.ON Next |
| Igloo Energy | 29 September 2021 | 179,000 | E.ON Next |
| MoneyPlus Energy | 7 September 2021 | 9,000 | British Gas |
| People's Energy | 14 September 2021 | 350,000 domestic, 1,000 others | British Gas |
| PFP Energy | 7 September 2021 | 82,000 domestic, 5,600 others | British Gas PFP was Places for People Energy 2014–2017 |
| Pure Planet | 13 October 2021 | 235,000 | Shell Energy |
| Symbio Energy | 29 September 2021 | 48,000 | E.ON Next |
| Together Energy (incl. Bristol Energy) | 18 January 2022 | 176,000 | British Gas |
| Utility Point | 14 September 2021 | 220,000 | EDF Energy |
| Bulb Energy | 23 November 2021 | 1,700,000 | Octopus Energy |
| Orbit Energy | 26 November 2021, finalised 29 November | 65,000 | Scottish Power |
| Entice Energy | 26 November 2021 | 5,400 | Scottish Power |