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 December, 2005

                              CONVERIUM HOLDING AG
                   ------------------------------------------
                 (Translation of registrant's name into English)

                                 Baarerstrasse 8
                                   CH-6300 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





Patinex AG acquires voting rights of 12.49% in Converium
Disclosure of shareholdings pursuant to Art. 20 SESTA

Zug, December 21, 2005

Converium Holding Ltd, Zug, has been notified that Patinex AG, Egglirain 24,
8832 Wilen, Switzerland, has acquired 12.49% of voting rights in Converium
Holding AG (5.06% in the form of 7,425,000 registered shares and 7.43% in the
form of purchase rights with entitlement to purchase 10,900,000 registered
shares).



Contacts:

Zuzana Drozd
Head of Investor Relations
zuzana.drozd@converium.com
--------------------------
Phone    +41 (0) 44 639 91 20
Fax      +41 (0) 44 639 71 20


Esther Gerster
Head of Public Relations
esther.gerster@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/ Terry Clarke
                                             ----------------
                                             Name:      Terry Clarke
                                             Title:     CEO


                                        By:  /s/ Christian Felderer
                                             ----------------------
                                             Name:      Christian Felderer
                                             Title:     General Legal Counsel



Date: December 22, 2005