Newcastle-based Atom Bank, the UK’s first digital-only bank, is searching for a new chief executive following the announcement that co-founder and CEO Mark Mullen has stepped down.

Mullen “will remain available to support the company until the end of the year.”

Atom’s chief financial officer Andrew Marshall will move into the role of Interim CEO.

“Andrew has been at Atom for over 10 years, serving as Chief Financial Officer for the last four years, and has been central to the running and success of the bank,” said Atom.

On Mullen, the company said: “Mark has led Atom since its founding in 2014, building the UK’s first digital-only bank into a profitable, scalable business that has lent over £5.8bn to customers and is a significant contributor to UK economic growth.

“His vision for a bank devoted to customer service has led Atom to become the UK’s highest rated bank on Trustpilot, consistently achieving market-leading Net Promoter Scores. The board is grateful for Mark’s significant contributions and the strong foundation he has established.

“After more than a decade of building and leading Atom, Mark and the board have agreed that now is the right time for new leadership to shape and drive the next phase of Atom’s growth. Mark will remain available to support the company until the end of the year.

“Andrew Marshall, Chief Financial Officer, will move into the role of Interim CEO. Andrew has been at Atom for over 10 years, serving as Chief Financial Officer for the last four years, and has been central to the running and success of the bank.

“The board will be initiating a market search to appoint a successor with a focus on identifying a leader who is well placed to drive long term-growth and value creation. An announcement of a permanent appointment will be made in due course.”