Entertainment mogul David Geffen has sold his duplex penthouse in Manhattan for $37.5 million, just a little more than a year after purchasing it for $31.5 million. A deed filed with the city on May 14 shows that the 12-room, 5,000-square-foot apartment at 810 Fifth Avenue sold for what is the second-most-expensive co-op sale in New York City’s history, after only Rupert Murdoch’s $44 million purchase in 2005 of a triplex penthouse in the building at 834 Fifth Avenue in Manhattan. Records show that the buyer is Pete Peterson, who co-founded the Blackstone Group. In March 2006, Geffen, 64, paid $31.5 million to buy the duplex penthouse co-op in the 13-story building at 810 Fifth Avenue from investment advisor John Foster and his wife Lynn, according to city records. Features in the three-bedroom unit include Central Park views, four baths, a formal dining room, a library, a double-wide living room with fireplaces, and a large reception room on the second level with a sprawling terrace, the New York Post reported. The duplex penthouse was once part of a triplex that the late Gov. Nelson Rockefeller once owned; Foster was reported to have purchased the apartment from the estate of Rockefeller’s ex-wife in 2000 for about $16 million, and then renovated the unit. Reports indicated that Geffen never moved into the unit. Check out the New York Observer’s recent coverage of Geffen’s purchase here and the New York Post’s coverage of it here and here.