He pledged to raise taxes on the rich, which helped Democrat Bill de Blasio win the mayoralty of New York, one of America's most expensive cities.
But that pledge also has some worried that higher-income New Yorkers will flee the city to seek lower taxes in the suburbs.
"If there is a major change in tax policy, it will definitely impact the real estate market. There's no question about that," said Dolly Lenz who has brokered more than $8 billion in Big Apple deals.
But she does not think such a change will happen.