Boston Properties Inc. has completed the previously announced sale of a 45 percent ownership interest in Times Square Tower for a gross purchase price of $684 million in cash.

In connection with the sale, Boston Properties formed a joint venture with an affiliate of Norges Bank. In addition to retaining a 55 percent interest in the venture, Boston Properties will provide customary property management and leasing services for the venture. The property is unencumbered by debt, and Boston Properties expects that it would distribute at least the amount of proceeds necessary to avoid paying a corporate level tax on the gain realized from the sale.

Boston Properties developed and completed the 1.25 million-square-foot Times Square Tower in 2004. It is currently 99 percent leased.