associated with such legal proceedings are described in more detail in note M, "Contingencies and Commitments," in IBM's 2018 Annual Report to Stockholders. The company believes it has adopted appropriate risk management and compliance programs. Legal and compliance risks, however, will continue to exist and additional legal proceedings and other contingencies, the outcome of which cannot be predicted with certainty, may arise from time to time. Risk Factors Related to IBM Securities: The company and its subsidiaries issue debt securities in the worldwide capital markets from time to time, with a variety of different maturities and in different currencies. The value of the company's debt securities fluctuates based on many factors, including the methods employed for calculating principal and interest, the maturity of the securities, the aggregate principal amount of securities outstanding, the redemption features for the securities, the level, direction and volatility of interest rates, changes in exchange rates, exchange controls, governmental and stock exchange regulations and other factors over which the company has little or no control. The company's ability to pay interest and repay the principal for its debt securities is dependent upon its ability to manage its business operations, as well as the other risks described under this Item 1A. entitled "Risk Factors." There can be no assurance that the company will be able to manage any of these risks successfully. The company also issues its common stock from time to time in connection with various compensation plans, contributions to its pension plan and certain acquisitions. The market price of IBM common stock is subject to significant volatility, due to other factors described under this Item 1A. entitled "Risk Factors," as well as economic and geopolitical conditions generally, trading volumes, speculation by the press or investment community about the company's financial condition, and other factors, many of which are beyond the company's control. Since the market price of IBM's common stock fluctuates significantly, stockholders may not be able to sell the company's stock at attractive prices. In addition, changes by any rating agency to the company's outlook or credit ratings can negatively impact the value and liquidity of both the company's debt and equity securities. The company does not make a market in either its debt or equity securities and cannot provide any assurances with respect to the liquidity or value of such securities. The company's corporate headquarters are located at an owned site in Armonk, New York. As of December 31, 2018, in aggregate, the company owns or leases facilities for current use consisting of approximately 75 million square feet worldwide. At December 31, 2018, IBM's manufacturing and development facilities in the United States had aggregate floor space of approximately 7 million square feet, of which 4 million was owned and 3 million was leased. Outside the U.S., similar facilities totaled more than 6 million square feet, of which 3 million was owned and 3 million was leased. The company's facilities are utilized for current operations of all its segments. Although improved production techniques, productivity gains, divestitures and infrastructure reduction actions have resulted in reduced manufacturing floor space, continuous maintenance and upgrading of facilities is essential to maintain technological leadership, improve productivity and meet customer demand. Refer to note M, "Contingencies and Commitments," on pages 115 to 117 of IBM's 2018 Annual Report to Stockholders, which is incorporated herein by reference. Not applicable. Item 4. Mine Safety Disclosures:  Item 3. Legal Proceedings:  Item 2. Properties:  Item 1B. Unresolved Staff Comments:  Not applicable. 18