AMP's expected announcement on Monday that Catherine Brenner will step down as chairman of the embattled company is unlikely to be enough to stave off an investor revolt at its annual general meeting next week.

The latest AMP board meeting on Sunday is believed to have agreed on the need for the chairman to exit as a way to demonstrate the board's accountability and to respond to the pressure on the company, which has lost $2.2 billion in market capitalisation over the last week.