Public Storage (the Trust) is a real estate investment trust (REIT). The Trust�s principal business activities include the acquisition, development, ownership and operation of self-storage facilities which offer storage spaces for lease, generally on a month-to-month basis, for personal and business use, and it also has interests in commercial facilities. At December 31, 2011, its operating segments are consisted of Domestic Self-Storage, European Self-Storage and Commercial. At December 31, 2011, it has controlling indirect interests in entities that own 26 self-storage facilities in the United States with approximately two million net rentable square feet. It also has direct and indirect interests in approximately 28.9 million net rentable square feet of commercial space located in 11 states in the United States primarily owned and operated by PS Business Parks, Inc. (PSB) under the PS Business Parks name. At December 31, 2011, it has a 42% interest in PSB.