The Hartford has signed a definitive agreement to sell its retirement plans business to Massachusetts Mutual Life Insurance Company for $400 million.

The sale is expected to close by the end of 2012, subject to regulatory approvals and other customary closing conditions. The purchase price is based on the future income stream from the enforced book of business for the retirement plans unit, said Hartford company spokesman Thomas Hambrick.

The deal is the second of three units The Hartford wants to sell to streamline its business and focus on property casualty, group benefits and mutual funds, Hambrick added.

In late July, the company confirmed it is selling independent broker-dealer network Woodbury Financial Services to American International Group Inc.'s Advisor Group. In April, the company said it was selling its annuity business to Forethought Financial Group, a Houston-based financial services company. The Hartford also is selling its life insurance business but has not announced a buyer yet.

The Hartford Retirement Plans business is primarily a defined contribution business with $54.9 billion in assets under management as of June 30. The business serves more than 33,000 plans with more than 1.5 million participants, and has a strong presence in the small to mid-sized corporate 401(k) and tax-exempt markets. It also provides administrative services for defined-benefit programs. As a result of the agreement, The Hartford's Retirement Plans employees will become part of MassMutual's Retirement Services Division.

The Hartford, Conn.-based firm announced in March that its Board of Directors had evaluated its business lines and concluded some businesses should be sold.

-Dorothy Hinchcliff