Form 6-K SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Report of Foreign Private Issuer Pursuant to Rule 13a-16 or 15d-16 of the Securities Exchange Act of 1934 For the month of March, 2007 CONVERIUM HOLDING AG ------------------------------------------ (Translation of registrant's name into English) Dammstrasse 19 CH-6301 Zug Switzerland ------------------------------------------------------- (Address of principal executive offices) Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F. Form 20-F X Form 40-F ------- ------- Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934. Yes No X ------- ------- If "Yes" is marked, indicate the file number assigned to the registrant in connection with Rule 12g3-2(b): 82- Not Applicable Disclosure of shareholdings pursuant to Art. 20 SESTA Zurich Cantonal Bank reduces its holding of Converium's registered shares to below 5% Zug, Switzerland - March 5, 2007 - Converium Holding Ltd has been notified that Zurich Cantonal Bank, Tessinerplatz 7, 8002 Zurich, Switzerland, has reduced its holding of registered shares of Converium Holding Ltd, Zug to below 5%. Contacts: Marco Circelli Head of Investor Relations marco.circelli@converium.com Phone +41 (0) 44 639 91 31 Fax +41 (0) 44 639 71 31 Beat Werder Head of Public Relations beat.werder@converium.com Phone +41 (0) 44 639 90 22 Fax +41 (0) 44 639 70 22 www.converium.com SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. CONVERIUM HOLDING AG By: /s/ Inga Beale Name: Inga Beale Title: CEO By: /s/ Christian Felderer Name: Christian Felderer Title: General Legal Counsel Date: March 6, 2007