He’s leaving home.

Famed ex-Beatle Paul McCartney and his wife, Nancy Shevell, have sold their penthouse on New York’s Fifth Avenue for about $8.5 million, roughly 45% less than what they paid for it in 2015, according to a person familiar with the situation.

Mr. McCartney, 79, and Ms. Shevell, 62, bought the co-op apartment for $15.5 million. They listed the unit for $12 million last June but reduced the price to $10.5 million in September, according to listings website StreetEasy. The buyer’s identity couldn’t be determined.

The duplex is located at 1045 Fifth Avenue, a bronze-glass apartment building overlooking the Central Park reservoir. The boutique, 12-unit building has a modern facade on a corridor better known for its classic prewar co-ops. 

The apartment was listed for sale as a white box; the listing described it as “a clean palette,” and “ready for your architect to create a one-of-a-kind custom residence.”

The unit was once the home of the building’s original developer, the late Manny Duell, records show. Mr. Duell, who built the structure in 1967, presented the apartment as a gift to his wife, according to the listing. Mr. McCartney and Ms. Shevell purchased the unit from Mr. Duell’s children. The unit is situated above the tree line of the park and has about 40 feet of floor-to-ceiling windows with terraces, according to the listing. 

Serena Boardman of Sotheby’s International Realty represented the sellers. CB Whyte of Douglas Elliman represented the buyer. Both agents declined to comment. 

Mr. McCartney wasn’t available for comment. He recently released a two-volume memoir, “The Lyrics”  which reflects on his lifetime of creative output. Ms. Shevell is a former member of the board of the New York Metropolitan Transportation Authority.