EXHIBIT 32.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER

PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Sotheby’s on Form 10-Q for the period ended June 30, 2011 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, William F. Ruprecht, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that, to my knowledge:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the registrant.

/s/ William F. Ruprecht

William F. Ruprecht

President and Chief Executive Officer

Sotheby’s

August 4, 2011