Workers suing Mutual of Omaha Insurance Co. over affiliated investment funds in the company’s 401(k) plan are moving forward with their proposed class action.

The workers put forth enough facts to show that Mutual of Omaha acted disloyally when it paid above-market rates to a subsidiary that acted as a plan service provider, Senior Judge Joseph F. Bataillon of the U.S. District Court for the District of Nebraska said Dec. 31.

Bataillon’s decision declining to dismiss the case followed a...