PS Business Parks, Inc. (PSB) is a fully-integrated, self-advised and self-managed real estate investment trust (REIT) and acquires, owns, operates and develops commercial properties, primarily multi-tenant flex, office and industrial space. PSB is in the commercial property business, with 85 business parks consisting of multi-tenant flex, industrial and office space. PS Business Parks, L.P. (the Operating Partnership) owns all of its assets. As of December 31, 2010, it owned and operated approximately 21.8 million rentable square feet of commercial space, consisting of 85 business parks, located in eight states: Arizona, California, Florida, Maryland, Oregon, Texas, Virginia and Washington. It focuses on owning concentrated business parks. During the year ended December 31, 2010, it acquired Shady Grove Executive Center, Austin Flex Portfolio, Parklawn Business Park, Tysons Corporate Center, Westpark Business Campus, and sold a 131,000 square foot office building.