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President & Owner

William Senné, President and owner of The Senné Company, founded his independent real estate organization in 2009 and has since methodically advanced the firm’s vision, purpose, and principles. Mr. Senné develops and implements corporate strategy across all business units, working closely with the leadership team to continually improve services, grow market share, and have a lasting positive corporate impact.

While he never takes a day off, he’ll occasionally attend a concert or go for a sail. He usually ends up back at the office before too long. William's inspiration flows from the confidence that members of his team find in their accomplishments. He is compelled to always do better than the day before, so that his team has a place where they can continue to achieve. 



Kate Pattison directs all operations at Senné Management. Since joining the company in 2013, Kate has been instrumental to its growth taking charge in business development, client service, and corporate vision efforts. She keeps things organized and running efficiently, which helps ensure that properties are properly cared for. Kate is a member of the Neighborhood Association of Back Bay, the National Association of Residential Property Managers, and the Community Association Institute. In her free time you might find Kate with her nose in a book or dancing to music, but more likely she is working!

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Director, Association Management

David Grosvenor is the head of the Condominium Association branch of the management team. Having worked in real estate management and development for over 10 years, David is an expert in building systems and customer relations. David has his bachelor's degree in Historic Preservation and Community Planning with a focus on architecture from the College of Charleston located in South Carolina. David is thrilled to be living and working in historic New York City. 

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David H. Keiran
Chief Financial Officer

David Keiran is Chief Financial Officer at Senné. David leads all of the company’s financial activities, working with the CEO to develop and manage capital structures, investor relations and corporate strategy execution. David joined Senné with over 30 years of commercial and residential industry experience with significant expertise in real estate accounting, taxation, risk management, capital sourcing, finance, investment, development, management and dispositions. He is also well versed in investment underwriting and analysis, asset and portfolio management, compliance, investor relations and reporting, budgeting and forecasting.

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Karen Hornstra manages the accounts payable and receivable for Senné, working together with David Keiran, CFO. Karen is a native Texan, but has lived in states across the US.  Karen is an avid runner, seamstress and landscaper. 

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