Boston Properties, a real estate investment trust, reported a net loss of $91.6 million for the quarter ended Dec. 31, compared to net income of $123.8 million for the same period in 2007 – a $215.4 million negative swing.

In the fourth quarter, the company recognized non-cash impairment charges aggregating a loss of approximately $188.3 million, representing the "other-than-temporary decline in the fair values below the carrying values of certain of the company’s investments in unconsolidated joint ventures," the company said.

Net income available to common shareholders was $125.2 million for 2008, compared to $1.3 billion for 2007. Net income available for the year ended 2007 included slightly more than $1 billion related to gains on sales of real estate and discontinued operations.

As of Dec. 31, 2008, the company’s portfolio consisted of 147 properties comprising approximately 49.8 million square feet, including 10 properties under construction totaling 3.8 million square feet and one hotel. The overall percentage of leased space for the 136 properties in service as of Dec. 31 was 94.5 percent.