The 1,830-square-foot house was built in 1997 in the neighborhood of Sagaponack Inland.
Castaldo is managing director focused on energy mergers and acquisitions at Bank of America.
He previously worked for seven years at Citigroup, where he most recently was in the firm's mergers and acquisitions group's director. Before that, he practiced corporate law at Simpson Thacher & Bartlett and Weil, Gotshal & Manges.
He received his bachelor's degree in economics and mathematics from Yale University and his law degree from Harvard Law School.
According to BlockShopper.com, there have been 14 home sales in Sagaponack in the past 12 months, with a median sales price of $4.2 million.
Address: 756 Sagg Road
Buyer(s): Andrew Castaldo
Seller(s): M &Amp; M L L C
Sale date: Oct. 13, 2009