Aviva chief executive Mark Wilson is stepping down from the top job and will exit in April 2019.
The UK insurance, pensions, investments and asset management firm said Wilson and its board have mutually agreed that Wilson will leave the group.
Aviva has commenced searching for Wilson's successor and appointed non-executive chair Adrian Montague in the meantime.
Montague will lead three executive directors: Andy Briggs (UK Insurance chief executive), Thomas Stoddard (chief financial officer) and Maurice Tulloch (International Insurance chief executives).
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Montague commented: "We have agreed with Mark this is the right time for a new leader to ensure Aviva delivers to its full potential. Our priority is to ensure, with our new chief executive, that we have the right strategy, focus, capabilities and leadership."
After the new chief executive is appointed, the board said Montague will revert to his role of non-executive chair.
Wilson was named chief executive in January 2013 with a mandate to turn the company around, the board said.
"Under his leadership, Aviva has been reshaped to significantly improve its financial performance and balance sheet strength," it said.
Wilson was responsible for streamlining Aviva's 28 markets to 14, growing operating profit and strengthening the balance sheet.
"The board and Mark believe that given the turnaround has been successfully completed, it is time for new leadership to take the group to the next phase of its development," the board said in a statement.
Wilson said: "When I joined Aviva, the company was in poor health. Aviva is very different today. I have achieved what I wanted to achieve and now it's time for me to move on to new things. It has been an honour to lead Aviva through this period of immense change."
He added that he was happy to leave the company in a strong position from which it can thrive.
In Australia, Aviva Investors runs multi-strategy funds and fixed income funds.
Aviva Investors is the global asset management arm of Aviva plc. It had US$482 billion ($648 billion) in assets under management as at March end.