Form 6-K

                             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 April, 2007

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

                                 Dammstrasse 19
                                   CH-6301 Zug
                    (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


News release
Converium Holding Ltd, Zug

Zug,  Switzerland  - April 17, 2007 - Converium  Files  Lawsuit  Against SCOR
S.A. and Patinex AG Alleging  Violations of United States Securities Laws.

On April 16, 2007,  Converium  filed a complaint in the United  States  District
Court for the  Southern  District  of New York  against  SCOR and  Patinex.  The
complaint alleges that the defendants  violated Sections 13(d), 14(d), and 14(e)
of the Securities Exchange Act of 1934, as amended, because, among other things,
(i)  SCOR  has  unlawfully  and  unfairly  excluded  Converium's  United  States
shareholders,   a  group  which  we  believe  represents  approximately  22%  of
Converium's  outstanding shares, from participating in SCOR's unsolicited tender
offer, and (ii) defendants failed to make proper  disclosures in connection with
their purchase and ownership of Converium securities.

Converium  is seeking an  expedited  discovery  and  briefing  schedule so as to
permit a hearing  on a motion for  preliminary  injunction  prior May 22,  2007,
which  (unless   extended)  is  currently  the  last  date  on  which  Converium
shareholders  may tender shares in  connection  with SCOR's  unsolicited  tender

Among  other  things,   Converium  is  seeking  an  order  enjoining  SCOR  from
consummating  the  offer  until  SCOR  and  Patinex  have  complied  with  their
obligations  under the  Williams  Act,  including  SCOR  extending  the offer to
Converium's United States shareholders and ADS holders.


Beat W. Werder                                  Marco Circelli
Head of Public Relations                        Head of Investor Relations             

Phone:     +41 44 639 90 22                     Phone:      +41 44 639 91 31
Fax:       +41 44 639 70 22                     Fax:        +41 44 639 71 31

Dr. Kai-Uwe Schanz Inken Ehrich
Chief Communication & Corporate Development     Investor Relations Specialist

Phone:     +41 44 639 90 35                     Phone:      +41 44 639 90 94
Fax:       +41 44 639 70 35                     Fax:        +41 44 639 70 94


About Converium

Converium is an independent  international  multi-line  reinsurer  known for its
innovation,  professionalism  and service.  Today  Converium  employs  about 500
people in 15 offices  around  the globe and is  organized  into  three  business
segments:  Standard Property & Casualty Reinsurance,  Specialty Lines and Life &
Health Reinsurance.  Converium has an "A-" ("strong")  financial strength rating
(outlook  stable) from Standard & Poor's and a "B++"  financial  strength rating
(outlook positive) from A.M. Best Company.


Important Disclaimers

This document contains forward-looking statements as defined in the U.S. Private
Securities Litigation Reform Act of 1995. It contains forward-looking statements
and  information  relating  to the  Company's  financial  condition,  results of
operations,   business,   strategy  and  plans,  based  on  currently  available
information. These statements are often, but not always, made through the use of
words or  phrases  such as  `seek  to',  `expects',  `aims'  `should  continue',
`believes',  `anticipates',  `estimates'  and  `intends'.  Such  statements  are
inherently subject to certain risks and uncertainties. Actual future results and
trends could differ  materially  from those set forth in such  statements due to
various  factors.  Such factors include our ability to refinance our outstanding
indebtedness   and  increase  our  use  of  hybrid  capital;   uncertainties  of
assumptions used in our reserving process; risk associated with implementing our
business  strategies and our capital  improvement  measures;  cyclicality of the
reinsurance industry; the occurrence of natural and man-made catastrophic events
with a frequency or severity exceeding our estimates; acts of terrorism and acts
of war;  changes in economic  conditions,  including  interest and currency rate
conditions that could affect our investment  portfolio;  actions of competitors,
including  industry   consolidation  and  development  of  competing   financial
products;  a decrease in the level of demand for our  reinsurance  or  increased
competition  in our  industries or markets;  our ability to expand into emerging
markets; our ability to enter into strategic investment partnerships;  a loss of
our key employees or executive  officers  without  suitable  replacements  being
recruited  within a suitable  period of time;  our  ability to address  material
weaknesses we have  identified in our internal  control  environment;  political
risks in the  countries in which we operate or in which we reinsure  risks;  the
passage of additional  legislation  or the  promulgation  of new regulation in a
jurisdiction  in which we or our clients operate or where our  subsidiaries  are
organized;  the  effect  on us and the  insurance  industry  as a result  of the
investigations  being carried out by the US Securities and Exchange  Commission,
New York's Attorney General and other governmental  authorities;  our ability to
regain past  customers  following any rating  upgrades and the resolution of the
investigations  being carried out by the US Securities and Exchange  Commission,
New York's Attorney General and other governmental  authorities;  changes in our
investment  results due to the changed  composition  of our  invested  assets or
changes in our investment policy;  failure of our  retrocessional  reinsurers to
honor their  obligations or changes in the credit  worthiness of our reinsurers;
our failure to prevail in any current or future  arbitration or litigation;  and
extraordinary   events   affecting  our  clients,   such  as  bankruptcies   and
liquidations, and other risks and uncertainties, including those detailed in the
Company's filings with the U.S. Securities and Exchange  Commission  (including,
but not  limited  to,  our  Annual  Report  on Form  20-F  filed  with  the U.S.
Securities and Exchange Commission) and the SWX Swiss Exchange. The Company does
not assume any obligation to update any forward-looking statements, whether as a
result of new information, future events or otherwise.



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: April 18, 2007