American Financial Realty Trust (AFR) has agreed to sell a 36-story Boston office building for roughly $800 million. The State Street Financial Center, a Class-A office building, was sold to a private real estate investment firm based in the Northeast. AFR declined to name the buyer.

AFR owns a 70% interest in the 1.1 million sq. ft. property. That interest is carried through a joint venture with IPC U.S. Real Estate Investment Trust. One possible reason that the buyer remains unnamed is that IPC has the right of first refusal on the sale.

In August, AFR announced that it would carry out a major corporate restructuring plan. Many analysts suspected that the Jenkintown, Pa.-based REIT would seek a buyer earlier this year. Shares in AFR were trading around $12 this afternoon, up 1.29% for the day.