Executive Vice President
Mark Sullivan is a native of Metropolitan Washington, DC, whose experience in the commercial real estate industry allows him to lead the Colliers International DC agency team to success. Mark offers clients the highest quality service through a strategic, thoughtful and proactively analytical approach. He uses his vast knowledge of historic and present market news, trends, and statistics to create added value for his clients. Over the course of his career thus far, Mark has represented approximately eight million square feet of office projects on behalf of both local developers and institutional owners/advisers, as well as completed over six million square feet of leasing transactions.
He began his career in 1994 with Cushman & Wakefield’s predecessor(s) (DTZ, Cassidy Turley and Cassidy & Pinkard) as a market analyst covering
downtown Washington, DC before moving to brokerage in 1996. Prior to joining Colliers, Mark served as an Executive Managing Director of Cushman
& Wakefield’s Washington, DC office where he specialized in office leasing.
- CREBA’s Rookie of the Year
- CREBA’s Leasing Transaction of the Year- DC (2004, 2008, 2018)
- CREBA’s Multi-Million Dollar Club
- Top 10 Leasing Agents in Washington, DC (2005, 2008, 2009, 2010, 2015, and 2018)
BS, Urban Studies & Planning - Virginia Commonwealth University
Memberships & Involvements
- CREBA Board of Directors (2009-2014) - Treasurer (2011), President (2013), Executive Committee (2011-2014), and President’s Council (2016-2018)
Senior Vice President
Matthew M. Venos is a member of the Washington, D.C. Landlord Agency Leasing team. In addition to the day-to-day management of listings, he excels in strategy, transaction analysis, and lease negotiation. Matthew’s legal background provides a unique insight and strength when negotiating agreements and positions him to strengthen his clients’ position in all aspects of the leasing process.
Prior to joining Colliers, Matthew spent 12 years at Cushman & Wakefield as part of the Landlord Agency Team where he completed over 6 million square feet of transactions.
Martha Naughten started working in the commercial real estate industry in 2010 and since then has proven to be a top performer among her peers. In 2019 alone, alongside her teammates, she executed 60 lease transactions totaling approximately 1.1 MSF at a collective lease value of $811 million. With her team at Colliers International, Martha specializes in landlord lease transactions. She is uniquely skilled at developing a holistic vision for her clients’ portfolios and has a strong understanding of asset management, both of which allow her clients to maximize asset value. In an article written about her by CREBA, Martha was noted for her “positive attitude, remarkable professionalism, strong problem-solving skills, and pleasant demeanor”.
Martha is very involved in the industry through organizations like CREW’s Member Services Committee and CREBA’s DC chapter. She also actively supports the greater DC community through a local charity called A Wider Circle and mentorship programs at her high school alma mater. Martha has been an adjunct professor at the University of Maryland, Master’s of Real Estate Development program since 2017.
Prior to joining Colliers International, Martha was a Senior Director at Carr Properties and formerly with JBG Smith and Vornado Realty Trust.