The Vanguard trading floor is the epicentre of one of the great financial revolutions of modern times, yet it is a surprisingly relaxed place.

A few men and women gaze at Bloomberg terminals. There is a muted television or two and a view of verdant suburban Philadelphia. No one is barking orders to buy or sell stock. For a $US4.2 trillion ($5.53 trillion) mutual fund giant that is still growing rapidly, it occupies a small fraction of the space of a typical Wall Street trading hub.