Former Morgan Stanley CEO John Mack and his wife Christy have put their Upper East Side abode on the market for a whopping $80M, making it the most expensive townhouse currently on sale in New York City. If sold at the listed price, the deal would break the city's townhouse record, previously set in June 2019 when 14 East 67th Street, a 22,000-square-foot mansion, was sold for $77.1 million.