Bill McNabb, the departing chief executive of Vanguard, has revealed he promised staff there would be no job cuts at the investment giant when he first became CEO at the height of the financial crisis.

McNabb, who was appointed chief of the Pennsylvania-based company just two weeks before Lehman Brothers collapsed in 2008, said he moved quickly to guarantee employees that their jobs would be safe at a time when a huge number of redundancies were being reported elsewhere.