Sotheby's said Friday it was offering staff voluntary severance packages to cut costs, despite selling more than $1.15 billion of art in the New York November auction season.

"After a review over the summer, the leadership of Sotheby's determined that the company would benefit from a lower and more flexible cost structure," it said in a short statement.

"With this in mind, we elected to begin limited cost reduction with voluntary separation programs that enable staff who choose to leave to do so with enhanced benefits."

The firm, which was founded in 18th century London but is now headquartered in New York, paid tribute to the "tremendous talent" of staff who had contributed to "outstanding results" this season.

"We look forward to entering the promising new year fresh, optimistic, and ready to invest to realize even more success," it added.

Sotheby's parted with $1.15 billion of impressionist, modern, post-war and contemporary art, narrowly beating the $1.05 billion of Christie's, in just over a week of November auctions in New York.

Christie's sold the top two star lots of the season -- a Modigliani nude for $170 million, making it the second most expensive work of art ever sold at auction, and Roy Lichtenstein's "Nurse" for $96 million.