Richard Ward is to resign as CEO of Lloyd's of London.
Having been in the role for almost eight years, his resignation will take effect at the end of December 2013.
The Council of Lloyd's and franchise board aim to appoint a successor before the end of this year.
Ward commented: "It has been a huge privilege to lead this great institution, and I am very proud of what has been achieved in my time as chief executive."
He added: "This has not been an easy decision to make but, as Lloyd's longest-serving CEO, I believe it is now right to hand over the reins to someone else to take Lloyd's into its next chapter.
"I'd like to take this opportunity to thank my management team, Lloyd's staff and the entire market for their support throughout my time at the helm."
John Nelson, chairman of Lloyd's, said: "I want to pay tribute to Richard, on behalf of the Council of Lloyd's and the market, for the truly outstanding service he has given over such a long period of time.
"The Lloyd's market is in a significantly stronger position that when he joined, and Richard deserves great credit for this, as does the management team. This early announcement allows us to select a successor in a timely manner."
