Anglo Irish Bank's chief operating officer Tiarnan O'Mahoney is to resign from the bank by the end of the year.
Mr O'Mahoney has been with Anglo Irish for almost 20 years, joining the board in 1993. Earlier this year he lost out to David Drumm in the race to succeed chief executive Sean Fitzpatrick.
Mr Fitzpatrick, who is himself retiring to become chairman from January, paid tribute to Mr O'Mahoney's contribution to the bank.
Mr O'Mahoney told RTE radio he had to look at what was best for him, for the bank and for David Drumm. He said he had been doing the job as number two for a long time and could not see himself having the enthusiasm to continue doing that.
Asked about his future plans, he said he would be looking at raising some equity in the new year, and would probably consider something in the capital markets area.
