A plan administrator and a plan trustee act as fiduciaries when they possess discretionary authority to manage the plan or its assets. Other individuals may have such discretionary control although not designated plan officials, e.g., a union official who had discretionary authority over benefit plan assets through his assumption of control over plan accounts was held to be a fiduciary although not so designated. But, a corporation’s so-called "manager of employee benefits," who possesses no discretionary authority over the plan may not be a fiduciary.