Nearly forty years after pointing the finger at active managers, there are still too many of them around, according to Burton Malkiel, author of A Random Walk Down Wall Street.

Malkiel, the Chemical Bank Chairman's Professor of Economics at Princeton University and board member at Vanguard, said: "I think the optimum passive level is three-quarters. The core of any portfolio ought to be managed passively. In the US at best there is only a quarter to a third of money indexed."