A five-bedroom penthouse at the Time Warner Center first listed for $65 million last year has sold for $37.5 million, just over half the asking price. The sale of the 8,300-square-foot home is the biggest residential deal in the city in the last year. Nothing has sold for more than $35 million since a Fifth Avenue co-op was bought last July for $48.84 million, according to appraiser Jonathan Miller. The seller, investor Gerhard Andlinger, bought the home for $25 million in March 2005. The apartment was purchased under the name Southerndown, Inc.