Energy broker Utilitywise has gone into administration, putting 1,000 jobs at risk.
The firm, which helps business clients to procure gas and electricity, said it had been unable to raise enough cash to cover its debts.
It also said a plan to sell the business had fallen through.
The collapse of Utilitywise (UTW) comes after a last-ditch rescue bid by the Newcastle-based company’s founder, Geoffrey Thompson.
Last month, it emerged it needed £10m to keep its business afloat, after coming up against “unexpected challenges and legacy issues”.
After failing to clinch the investment from shareholders, the company put itself up for sale at the end of January.
But in a statement on its website on Wednesday, it said the formal sale process for the group announced by the board “did not result in any offers”.
“Consequently, the directors of UTW sought the appointment of administrators.”
The firm has appointed FTI Consulting to handle the administration process and said its energy brokerage business would stop trading immediately.
However, its other subsidiary companies will continue trading while buyers for those parts of the group are sought.
Mr Thompson, who stepped down from the board two years ago, built UTW from a bedroom in South Shields into a multi-million-pound business listed on the AIM stock exchange.
According to a report in the Sunday Telegraph, the firm had recently warned staff it could not guarantee it could pay them in March.