One reason why a portfolio investor may want to prefer an index fund over a managed (mutual) fund is:

1. Managed funds or mutual funds tended to perform worse than index funds.

2. The fees for managed funds tend to run about 1.5% a year compared to 0.5% or less for index funds.

3 The lower index fund fees, even at the same return, would provide an investor with a much higher return over the long run.

4. All the above statements are true.