Corporate Property Associates 18 - Global Incorporated ("CPA:18 - Global") and, together with its consolidated subsidiaries, we, us, or our, is a publicly owned, non-traded REIT that invests in a diversified portfolio of income-producing commercial properties and other real estate-related assets, both domestically and outside the United States. As a REIT, we are not subject to U.S. federal income taxation as long as we satisfy certain requirements, principally relating to the nature of our income and the level of our distributions, among other factors. We conduct substantially all of our investment activities and own all of our assets through CPA:18 Limited Partnership, a Delaware limited partnership, which is our Operating Partnership. In addition to being a general partner and a limited partner of the Operating Partnership, we also own a 99.97% capital interest in the Operating Partnership. WPC-CPA:18 Holdings, LLC ("CPA:18 Holdings"), also known as the Special General Partner, a subsidiary of our sponsor, W. P. Carey Inc. ("WPC"), holds the remaining 0.03% special general partner interest in the Operating Partnership.
Our primary investment strategy is to acquire, own, and manage a portfolio of commercial real estate properties. Our single-tenant, net-leased properties are leased to a diversified group of companies on a single-tenant, net-leased basis and generally require the tenant to pay substantially all of the costs associated with operating and maintaining the property, such as maintenance, insurance, taxes, structural repairs, and other operating expenses.
In addition, our portfolio at December 31, 2018 included self-storage and multi-family investments (comprised of multi-family residential properties, student housing development projects, and student housing operating properties), which we refer to as our Operating Properties.