The boss of Ulster Bank parent company Royal Bank of Scotland has announced he is resigning after more than five-and-a-half years at the helm, saying it is the "right time" to step down.
Ross McEwan has a year's notice period and will stay in the post until a successor has been appointed to ensure an "orderly handover".
Belfast man and former Danske Bank chief executive Gerry Mallon has been tipped as a possible external candidate.
Mr Mallon became the chief executive of Tesco Bank in July last year after nearly two years as chief executive of Ulster Bank in the Republic. He previously led Danske Bank in Northern Ireland for seven years.
The news of Mr McEwan's departure came ahead of the lender's annual general meeting.
Mr McEwan said he had achieved the strategy set out when he joined the bank, having returned it to profitability and put it on a firmer footing.
"After over five and a half very rewarding years, and with the bank in a much stronger financial position, it is time for me to step down as CEO," he added.
"It is never easy to leave somewhere like RBS. However, with much of the restructuring done and the bank on a strong and profitable footing, I have delivered the strategy that I set out in 2013 and now feels like the right time for me to step aside and for a new CEO to lead the bank."
RBS chairman Sir Howard Davies said the search for Mr McEwan's successor would start immediately, with the bank considering both internal and external candidates.
Alison Rose, deputy chief executive of NatWest Holdings, is seen as the leading internal candidate. Her appointment late last year sparked intense speculation she was being lined up as a successor to Mr McEwan.
Analyst John Cronin, of stockbrokers Goodbody, said Mr Mallon could be approached as an external candidate.
But he added: "Given he did not stay at RBS for a very long time as head of Ulster Bank, as well as the fact that he has only been in situ at Tesco Bank since last July, I think it would be seen by the RBS board as too big a step, too soon.
"With that said, Gerry is clearly a very capable chief executive and I believe we will see him continue to rise to great heights in the banking world."