Alexandria Real Estate Equities is a real estate investment trust primarily engaged in the acquisition, development, and leasing of urban offices on science and technology campuses throughout the United States. The company redevelops offices, warehouses, and shell space for its tenants in areas close to high concentrations of specialized research institutions and businesses. The majority of Alexandria's real estate portfolio is split between the Greater Boston and San Francisco areas. The company derives nearly all of its income in the form of revenue from its tenant companies. Alexandria's largest customers in terms of revenue are public biotechnology, multinational pharmaceutical, life science product, and academic and medical research entities.