The Co-operative Group chief executive Peter Marks is to retire from the business next May.
Marks will leave the company after 45 years with the wider movement and six years in his current role.
The company said it has been “transformed operationally” under his leadership after he led the acquisition and integration of Somerfield.
Marks retires shortly after acquiring the Lloyds Banking Group Verde business and leading a merger with Britannia.
The Co-operative Group said that it will now start the hunt for an internal and external candidate for his successor.
Marks’ retirement follows a series of changes within the business. Paul Pester, currently chief executive of the Lloyds Project Verde business, will become chief executive of The Co-operative Banking Group while Steve Murrells has recently started his new role as chief executive of Co-operative Food.
Marks said: “I am extremely proud of what has been achieved at The Co-operative Group over the past five years. We have transformed this business while staying true to our roots as a mutual, ensuring that we now offer value with values to millions more customers than ever before.
“Our ownership model means that the top management team has been able to take strategic decisions for the long term, in the interests of our members and customers and I am confident we have laid the foundations for the ongoing success of the group.
“Given all we have achieved, it now feels like the right time for me to stand down.”
Co-operative Group chairman Len Wardle said: “Peter has done a truly outstanding job for The Co-operative Group. He was the architect of the current strategy to ensure that we developed real scale in our key businesses. Peter has led a strong management team which has ensured that those businesses are now stronger and better able to deliver for our millions of customers.”
Marks leaves on May 18 2013.