Mutual of Omaha Insurance Co. is the latest company to be sued over the affiliated investment products in its 401(k) plan.

The proposed class action accuses Mutual of Omaha of filling its 401(k) plan with affiliated investment funds that were essentially funds offered by third parties plus an extra layer of fees that went to the Nebraska-based insurer. The company also tacked on extra layers of fees to unaffiliated funds in the 401(k) plan, according to the complaint.

These extra...