A 401k plan generally involves four parties: the contributing employees, the sponsoring employer, a plan administrator, and various investment advisors.
A 401k plan aims to grow employees’ contributions through investments for retirement. To better manage a plan’s ongoing operation, once the plan has been set up by the employer for employee participation, the employer will usually appoint a plan administrator to take care of the plan with tasks such as recording keeping and accounting, providing customer service, giving educational seminars, etc…
But the actual investment of the plan contributions are managed by a group of investment companies, such as mutual fund brokerages (Vanguard, Fidelity, and ShareBuilder are a few), that the plan administrator has contracted with.
There are two major 401k fees in connection with plan administration and investment management.