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Mark joined TTR Sotheby’s International Realty in January, 2011 as CEO & Managing Partner, building further on a distinguished career as a widely recognized leader in the Washington real estate community. Prior to joining the firm, Mark served as Executive Vice President at WEST*GROUP, one of the region’s leading commercial real estate development firms. After 23 years at WEST*GROUP, Mark played a leading role in the sale and disposition of the historic $1.5 billion WEST*GROUP portfolio. Today, Mark is focused on corporate management, strategic marketing, business development, and the cultivation of enhanced resources to expand the unique relationships, expertise and global services which TTR Sotheby’s International Realty offers to its associates and clients. Mark has also been personally responsible for a number of the firm's record-setting transactions including the $45 million sale of the Kimsey Estate in 2020, the $43 million sale of the historic Merrywood Estate in 2018, and the $35 million sale of the Schar Estate in 2017, among others. Together, these represent three of the top four sales in the history of the Washington region. These and other significant transactions rank Mark among the top real estate professionals worldwide. He is listed as one of the 200 most influential leaders in residential real estate by The Swanepoel Power 200 (SP200) and as one of Washington's most influential business leaders in the Washington Business Journal's Power 100. Mark serves as a member of the Board of Directors and the Executive Committee of Bright MLS, Inc., the largest multiple listing service in the United States. In the non-profit world, Mark also has established a leadership role and serves as Chairman of the Board for Teach for America in the DC Region. He also serves on the boards of Halcyon, the INOVA Schar Cancer Institute, and the Hillwood Estate and Museum. Previously, Mark served on the Board of Visitors George Mason University where he chaired the Real Estate Committee, the Board of Directors of the Fairfax County Economic Development Authority, the Board of Directors of the Wolf Trap Foundation, and the Board of Trustees of the Potomac School. Lowham is a native of Wyoming and prior to joining WEST*GROUP, he worked in the Corporate Finance Department of Kidder, Peabody & Company in New York. He earned his undergraduate degree in Economics from Stanford University and a Masters in Business Administration from the Stanford Graduate School of Business.