Billionaire Carl Icahn’s daughter Michelle and her husband Michael Nevin just sold their Upper West Side duplex at a loss — closing the deal during the height of the coronavirus pandemic.

The co-op, at 10 W. 66th St. near Lincoln Center, was last asking $3.99 million and sold for $3.65 million.

The couple bought the 28th-floor unit for $4.27 million — down from its then-asking price of $4.5 million — in 2018, according to property records.

But they never lived there, sources say. (They bought it from opera legend Marilyn Horne, who had reportedly nabbed it for $126,000 in the 1970s.)

The 2,175-square-foot duplex features an entry foyer, an oversized living room with the private terrace, a windowed eat-in chef’s kitchen, formal dining room and stunning park views.

Activist investor Icahn moved himself and his hedge fund to Miami in the fall of 2019, even though he still owns two penthouse apartments in Manhattan’s Museum Tower, overlooking the Museum of Modern Art.

Michelle’s sale went into contract before coronavirus hit New York, but the walk-through and closing were done remotely, all online, at the height of the pandemic. The 33-story building comes with a rooftop sundeck and a bike room. The buyers are David Khayat and Karen Bouhadana. The listing brokers were Douglas Elliman’s Michael Lorber and Alexander Boriskin.