If market are completely efficient, it will mean that all the publicly available information as well as privately information have already been discounted into the stock price so, There is no scope for making any additional rate of return, because intrinsic valuation is equal to the fair valuation of the market and there is no price discrepancies so there is is passive investment which will be advocated.

When the markets are completely efficient, it will mean that portfolio manager should always try to look for passive management rather than active management of the fund, because passive management will help him in order to match with the index rate of return whereas, active investment will be leading to under-performance in respect to the overall market.

There is a role of portfolio manager in order to manage with the risk associated with investment and the allocation so portfolio manager will be trying to ascertain the overall amount of risk associated with investment and he will allocate on the overall investment into various different types of classes in order to minimise the risk and channelize the fund in optimum index fund, which will be helping the investor in order to maximize the rate of return so there will always be a need of passive portfolio fund manager.