Board of Directors

Steven Vondran is the President and Chief Executive Officer of American Tower Corporation. Prior to this role, he was the Executive Vice President and Global Chief Operating Officer of American Tower. Mr. Vondran has held various leadership positions since joining the company in 2000, including serving as American Tower’s Executive Vice President and President, U.S. Tower Division, which included overseeing the U.S. data center business. As a member of the Corporate legal team, Mr. Vondran served in a variety of roles until August 2004, when he was appointed Senior Vice President of U.S. Leasing Operations. Later, in August 2010, he assumed the role of Senior Vice President, General Counsel for the U.S. Tower Division. Mr. Vondran joined the Cellular Telecommunications Industry Association (CTIA) board of directors in September 2018, and he served on the board of the Wireless Infrastructure Association (WIA) between 2018 and 2024. Mr. Vondran is a member of the Business Roundtable. Prior to joining us, Mr. Vondran was an associate at the law firm of Lewellen & Frazier LLP, served as a telecommunications consultant with the firm of Young & Associates, Inc., and was a Law Clerk to the Hon. John Stroud on the Arkansas Court of Appeals. He received his J.D. with high honors from the University of Arkansas at Little Rock School of Law and a Bachelor of Arts in Economics and Business from Hendrix College.

Ms. Reeve has been a Director since March 2002 and was appointed as Chair of the Board in May 2020. She served as the Lead Director of the Board from May 2004 to May 2020. In May 2009, Ms. Reeve was reappointed to the Nominating and Corporate Governance Committee, having served on that Committee from August 2002 to February 2005. From April 2004 to June 2016, Ms. Reeve served on the Compensation Committee and served as its Chairperson from April 2004 to May 2009. Ms. Reeve also served on the Audit Committee from August 2002 to July 2007. From November 1989 to August 2004, Ms. Reeve was the President and Chief Executive Officer and a Director of Lightbridge, Inc., a global provider of mobile business solutions, offering products and services for the wireless communications industry. Prior to joining Lightbridge in 1989, Ms. Reeve spent 11 years as a consultant and in a series of executive positions at the Boston Consulting Group, Inc. Ms. Reeve previously served on the board of Frontier Communications Corporation from October 2010 to April 2021, including as the company’s Chairperson between April 2016 and April 2021, and served on the board of Sonus Networks, Inc. from August 2013 to May 2017.

Ms. Chambliss has been a Director since March 2022 and was appointed to the Compensation Committee in May 2022. She currently serves as the Senior Vice President of IBM Consulting in the Americas. She previously served as the Global Chief Operating Officer and Senior Vice President for IBM Consulting. Ms. Chambliss served in various other senior leadership roles at IBM from late 2002, including as the Chief Technology Officer for IBM Global Business Services (GBS) and as the Managing Partner for the Industrial and Distribution Markets in GBS within the United States. Ms. Chambliss joined IBM through the acquisition of PricewaterhouseCoopers (PwC) Consulting, where she was a Partner. Ms. Chambliss was an Independent Director on the Board of Directors for CoreSite Realty Corporation from September 2016 through December 2021, when it was acquired by American Tower. She graduated from Virginia Tech with a degree in Management Science and a specialization in Decision Support Systems.

Ms. Clarke has been a Director and member of the Audit Committee since December 2021. She is the Chair of Africa.com LLC, a media holding company launched in 2010 with an extensive array of platforms that reach a global audience interested in African content and community. Prior to founding Africa.com, Ms. Clarke was a Managing Director in the investment banking division of Goldman Sachs & Co. for over 12 years, where she led corporate finance and merger & acquisition transactions for corporate clients in the industrials and real estate sectors (1989 to 1995 and 2004 to 2010, respectively). Ms. Clarke currently serves on the board of directors of Arthur J. Gallagher & Co., the global insurance brokerage with operations in 56 countries. She served on the board of Australian fintech, Change Financial from 2016 to 2020, and as board chair from 2018 to 2020. She also served on the board of Cim Finance, a financial services company, from 2016 to 2020. She served on President Obama’s Advisory Council on Doing Business in Africa from 2014 to 2016. She is a member of the Council on Foreign Relations and the Chair of the Advisory Board of the Smithsonian National Museum of African Art.

Mr. Frank has been a Director and member of the Audit Committee since January 2021. He was appointed to the Nominating & Corporate Governance Committee in May 2023, and in May 2024, he was appointed as its Chair. Mr. Frank is a Partner at Banneker Partners, a private equity firm focused in the enterprise software sector. He served as the Chief Executive Officer of Turning Technologies, an education technology company, from June 2019 to September 2021, and has led other enterprise software and services companies, such as Kibo Software, as Chief Executive Officer, from January 2016 to December 2018, and Aptean Software, as Chief Operating Officer, from October 2011 to December 2015. Prior to that, Mr. Frank was a member of the Executive Committee and held a series of leadership positions at Alcatel-Lucent, between February 2005 and October 2012, including Global President of Solutions and Marketing, President of the Professional Services Division and Chief Technology Officer of Alcatel North America. During his tenure with Alcatel-Lucent, he was also responsible for the joint engagement with Reliance Industries in Mumbai, India. Mr. Frank previously held positions at AT&T Bell Laboratories, BellSouth Telecommunications and venture-backed communications startups, Broadband Office and Masergy Communications. He currently serves on the board of directors of Orbcomm, Inc. and Calero-MDSL, and as a member of the Board of Councilors for the Marshall School of Business at the University of Southern California. He has previously served on the boards of industry organizations, including Alliance for Telecommunications Industry Solutions, the Telecommunications Management Forum and the USC Center for Telecommunications Management.

Mr. Hormats has been a Director since October 2015. He was appointed to the Nominating and Corporate Governance Committee in February 2016 and served as its Chair from May 2021 until May 2024. Mr. Hormats is a Visiting Lecturer at Yale University’s School of Management. He was appointed Managing Director of Tiedemann Advisors in March 2020, following his five-year tenure as a member of Tiedemann’s Investment Advisory Committee, and served as such until July 2022, after which he continued to serve as an advisor through 2023. He was a Vice Chairman of Kissinger Associates, Inc., a strategic international consulting firm, from 2013 to 2019. From 2009 to 2013, he served as Under Secretary of State for Economic Growth, Energy and the Environment. Prior to that, he was Vice Chairman, Goldman Sachs (International) and Managing Director of Goldman, Sachs & Co., which he joined in 1982. Mr. Hormats formerly served as Assistant Secretary of State for Economic and Business Affairs, Ambassador and Deputy U.S. Trade Representative and Senior Deputy Assistant Secretary for Economic and Business Affairs. He also formerly served as a senior staff member for International Economic Affairs on the National Security Council. He served as a Director of Grace Therapeutics, LLC, a private biopharmaceutical company until December 2020. He has served on the Board of Visitors of the Fletcher School of Law and Diplomacy and the Dean's Council of the John F. Kennedy School of Government. He also formerly served as Director of Human Genome Sciences, Inc. Mr. Hormats is a member of the Council on Foreign Relations and the Economic Club of New York.

Ms. Lieblein was appointed as a Director in June 2017. She was appointed to the Compensation Committee in May 2021, and in May 2024, she was appointed as its Chair. From June 2017 to May 2021, Ms. Lieblein served on the Audit Committee. Ms. Lieblein most recently served as Vice President, Global Quality of General Motors Company (GM), a multinational corporation that designs, manufactures, markets and distributes vehicles, from November 2014 to December 2015. Ms. Lieblein joined GM in 1978 and has held a variety of leadership positions in engineering, supply chain management and international operations. Ms. Lieblein’s leadership positions have included serving as Vice President, Global Purchasing and Supply Chain from 2012 to 2014, GM Brazil President from 2011 to 2012, GM Mexico President from 2008 to 2011 and Vehicle Chief Engineer from 2004 to 2008. Ms. Lieblein also served on the board of directors of Southwest Airlines Co. from 2016 to 2022. She currently serves as a director of Honeywell International, Inc. and of Cox Enterprises, Inc.

Mr. Macnab has been a Director since December 2014. Mr. Macnab was appointed to the Compensation Committee in May 2018 and served as its Chair from May 2019 to May 2024. From December 2014 to December 2019, Mr. Macnab served on the Audit Committee. From February 2004 to April 2017, Mr. Macnab served as Chief Executive Officer of National Retail Properties, Inc., a publicly traded Real Estate Investment Trust (REIT), and served as Chairman of the Board from February 2008 to April 2017. Prior to joining National Properties, Mr. Macnab was the Chief Executive Officer, President and a Director of JDN Realty Corporation, also a publicly traded REIT, from April 2000 through March 2003. Mr. Macnab previously served as a director of DDR Corp. and Eclipsys Corporation. He also previously served on the board of directors and as Chair of the Governance Committee of the Cadillac Fairview Corporation Limited, a private company and a wholly owned subsidiary of the Ontario Teachers' Pension Plan. Mr. Macnab is currently a director of VICI Properties, Inc. and Independence Realty Trust, Inc.

Mr. Ray has been a Director since March 2024. He was appointed to the Compensation Committee in May 2024. Mr. Ray currently serves on the board of directors, compensation committee and environmental, social and governance committee of Ziff Davis, a vertically focused digital media and internet company. Mr. Ray most recently served as T-Mobile’s President of Technology until 2023. Mr. Ray joined T-Mobile (then VoiceStream) in April 2000 and, from December 2010 to November 2019, served as its Chief Technology Officer. Prior to that, Mr. Ray served as Network Vice President for Pacific Bell Mobile Services. He also serves on the U.S. President’s National Security Telecommunications Advisory Committee (NSTAC). Mr. Ray has served as Chairperson of the Board of Governors of 5G Americas, as well as the Vice Chairman of the Cellular Telecommunications Industry Association (CTIA). In addition, he has served as a member of the National Telecommunications and Information Administration’s Commerce Spectrum Management Advisory Committee (CSMAC) and the Federal Communications Commission’s Communications Security, Reliability and Interoperability Council (CSRIC).

Ms. Reed has been a Director since May 2007. In November 2007, Ms. Reed was appointed to the Audit Committee and served as its Chair from May 2015 to May 2024. Ms. Reed is currently serving as a healthcare services consultant. Ms. Reed previously served as the Senior Vice President, Finance and Chief Financial Officer of Medco Health Solutions, Inc., a leading pharmacy benefit manager, until March 2008. Upon joining Medco in 1988, Ms. Reed served in finance and accounting roles of increasing responsibility and was appointed Senior Vice President, Finance in 1992 and Chief Financial Officer in 1996. Prior to joining Medco, Ms. Reed's experience included finance roles at Aetna/American Re-Insurance Co.,CBS Inc., Standard and Poor's Corp. and Unisys/Timeplex Inc. Ms. Reed served on the board of directors of DynaVox until 2011 and on the board of directors of Health Management Associates, Inc. until 2014. Ms. Reed also served on the board of directors of Mallinckrodt plc and of Waters Corporation. She also served as a Trustee for St. Mary's College of Notre Dame, Indiana until April 2015.

Mr. Tanner has been a Director since September 2019. He was appointed to the Audit Committee in December 2019, and in May 2024, he was appointed as its Chair. Mr. Tanner served as Executive Vice President and Chief Financial Officer of Lockheed Martin Corporation from September 2007 until February 2019. Mr. Tanner joined Lockheed Martin in 1982 and, prior to being appointed Chief Financial Officer, held a variety of finance leadership positions at Lockheed Martin, including as Vice President of Finance and Business Operations, Lockheed Martin Aeronautics, from April 2006 to September 2007 and Vice President of Finance and Business Operations, Lockheed Martin Electronic Systems, from May 2002 to March 2006. Mr. Tanner is also a Director of Truist Financial Corporation (formerly SunTrust Banks, Inc.).