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).[1]
In 2008, the Big Six still had over 99% of domestic and small business customers.[1] 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.[1] 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.[2][3] 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.[4]
- ^ a b c "Energy Supply Probe – Initial Findings Report" (PDF). Ofgem. 6 October 2008. pp. 27–30. Archived (PDF) from the original on 31 October 2008. Retrieved 1 November 2021.
- ^ "Electricity supply market shares by company: Domestic (GB)". Ofgem. 1 January 2020. Archived from the original on 6 February 2020. Retrieved 6 February 2020.
- ^ "Gas supply market shares by company: Domestic (GB)". Ofgem. 1 January 2020. Archived from the original on 6 February 2020. Retrieved 6 February 2020.
- ^ "New UK energy giant created in SSE-Ovo deal". BBC News: Business. 13 September 2019. Retrieved 16 September 2019.