ERISA requires that retirement plan documents designate who is responsible for investment of plan assets. In the case of defined benefit plans, the plan trustee or other designated fiduciary makes investment decisions, unless authority to manage the investments is delegated to one or more investment managers.

In the case of individual account plans, a plan may permit participants or beneficiaries to make investment decisions with respect to their individual accounts. It is common for 401(k) plans to provide participants with investment authority with respect to their own elective contributions.