The lone bidder who spent $101 million at Sotheby’s last Tuesday night for Giacometti’s “Chariot,’’ a 1950 sculpture of a spindly woman riding atop a chariot, was the hedge fund billionaire Steven A. Cohen, experts with knowledge of the sale said Monday. The sculpture, which came from the collection of Alexander Goulandris, a member of the Greek shipping family, is considered among the artist’s finest.

“It’s one of the great 20th-century sculptures,’’ said William Acquavella, the Manhattan art dealer.