NEW YORK — A sculpture of a stainless steel heart hanging from a golden bow sold Wednesday for $23.6 million, becoming the most expensive piece by a living artist ever auctioned, a Sotheby's spokeswoman said.

The bright magenta "Hanging Heart" sculpture, considered one of Jeff Koons' most important works, also set a records for Koons at auction, Sotheby's spokeswoman Lauren Gioia said.

The previous record for a living artist was Damien Hirst's "Lullaby Spring," which sold for $19.5 million at Sotheby's in London in June. Hirst's piece was a stainless steel cabinet containing 6,136 handcrafted and painted pills.

The Koons work was bought by the Gagosian Gallery, which had picked up his "Diamond (Blue)" sculpture for $11.8 million at a Christie's auction on Tuesday.

"Hanging Heart," nearly 9 feet tall and weighing more than 3,500 pounds, is from Koons' "Celebration" series, inspired by celebratory milestones such as birthdays and anniversaries. The "Diamond (Blue)" also is from the series.

"Koons is an artist who doesn't allow compromise, and 'Hanging Heart' is all about making an impossibility possible," said Tobias Meyer, head of Sotheby's contemporary art department.

The sculpture was offered for sale by a private American collector and had a pre-sale estimate of $15 million to $20 million. Its sale price included an auction house commission.