Norwich-based insurance giant Aviva has said that up to 800 jobs could go in the latest round of restructuring.
The insurance group, which employs 18,500 people in the UK, warned jobs could be lost under a restructuring being overseen by new chairman John McFarlane.
Aviva said its record of keeping role reductions to a minimum meant the figure was likely to be lower.
Mr McFarlane, who has already begun the process of jettisoning non-core businesses, hopes to save £400 million by 2014 through simplifying the business.
But unions have hit out at the move, saying staff were paying "the price of boardroom failure", a union said today.
David Fleming, national officer for the Unite union, said: "Our members face being asked to pay the price of boardroom failure and Unite is dismayed that what started out as a shareholders' revolt on executive pay will result in a jobs cull. This is totally unacceptable."
The cost-cutting drive will focus on removing layers of management, while Aviva has said it could guarantee only 70% of the jobs in the UK life and pensions department.