The Bayford Group, an investment company which owns Gulf Gas and Power, has acquired challenger brand E (Gas and Electricity).
According to Companies House, Leeds-based Bayford took ownership of the supplier from E Holdings Limited on 9 March.
Birmingham-based E has more than 300,000 customers and employs around 150 people.
Last year both E and failed supplier Economy Energy, along with consultancy firm Dyball Associates, were found by Ofgem to have breached competition law.
The three companies were fined £870,000 collectively by the regulator after they infringed the Competition Act 1998.
Between January and September 2016 Economy Energy, E and Dyball Associates had an anti-competitive agreement preventing the two suppliers actively targeting one another’s customers through face-to-face sales.
Bayford’s acquisition of E comes in the same week EDF Energy acquired the 190,000 customers of iSupply Energy from Swedish state-owned renewables giant Vattenfall.