On the heels of a fantastic $181.8 million sale of Impressionist and modern art, where collectors lapped up Renoirs, Picassos, and Giacometti, Sotheby's posted a sobering net loss of $57.8 million (89 cents a share). This is worse than the $47 million loss (73 cents a share) it delivered a year earlier. Revenue was off 41% to $44.9 million for the quarter. But it could have been much worse. The elimination of price guarantees helped the auction house protect itself from paying for unsold lots.