Auction house Sotheby's has widened its third-quarter net loss to $29.7 million comparied to the year-ago quarter, when it posted a net loss of $19.4 million, the company announced in its earnings report after trading ended Monday.

Diluted loss per share was $0.44 versus $0.29 a year ago. Market consensus had the company posting a net loss of around $0.35 per share.

The wider loss was blamed on higher general and administrative expenses and lower auction commission revenues, according to the New York-headquartered company in its earnings statement.

Sothyby's total revenues for the three-month period ending Sept. 30 was $58.2 million versus $73.1 million in the corresponding 2010 quarter, as its auction and related revenues slipped 4 percent o $52.9 million.

Sotheby's noted that auction sales in the third quarter traditionally only represent between 7 and 10 percent of annual auction sales, and the third quarter usually serves as a period of loss for the company.