Wisconsin-based Northwestern Mutual Life Insurance Co. is reportedly exploring a possible sale of its Russell Investments asset management business. Russell Investments has $247 billion in assets under management.

Sources told Reuters on Tuesday that Northwestern Mutual is discussing selling its Russell Investments subsidiary because it has decided it is not a core part of its business.

Russell Investments provides pension consulting, investment management, transition management services and indexes such as the Russell 1000 Global Index, the report said.

Sources said that if Northwestern Mutal decides to go ahead with a sale, it is unclear if the asset management business would be sold in its entirety or broken up, Reuters said.

It could not also be determined how much Northwestern Mutual would receive if it decides to sell the the firm. Northwestwern Mutual bought Russell Investments, which was then called Frank Russell Company, in 1999 for $1.2 billion, the report said.

Sources also said that Russell Investments would not be alone in selling its index business. British investment bank Barclays PLC is also exploring a sale of its index business.