In 2015, the best apartment flippers saw seven-figure gains within 18 months of buying their units, according to data compiled by listings website CityRealty. Among them were Robert and Kathleen Kaswell, founder of a real estate firm and a former CEO of Nine West Group, respectively. The husband and wife profited more than 50% on their unit in Walker Tower, located at 212 W. 18th St. in Chelsea.
