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 April, 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


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News release
Converium Holding Ltd, Zug


Zug,  Switzerland - April 13, 2007 - Converium urges shareholders to reject SCOR
offer -  hostile  approach  could  result in loss of  business  of up to USD 800
million

Converium today, after close of trading, will issue its official Board report in
accordance  with  article  29 (1) of the  Federal  Act on  Stock  Exchanges  and
Securities  Trading to the tender offer  published  last week by its  competitor
SCOR S.A. for the registered  shares in Converium held by the public.  Tomorrow,
such  official  Board report will be  published  in Neue Zurcher  Zeitung and Le
Temps.

Converium's  Board of Directors  urges its  shareholders to reject SCOR's offer,
believing it to  fundamentally  undervalue  the  Company's  franchise and growth
prospects. In addition, the Board of Directors anticipates significant business,
integration and execution risks arising from the hostility of SCOR's offer.  The
hostile   nature  of  the  bid  threatens  to  destroy  value  for   Converium's
stakeholders  and to undermine the stability of SCOR's  shares,  the bulk of its
acquisition currency.

Markus Dennler,  Chairman of Converium's  Board of Directors,  comments:  "After
careful  consideration  of SCOR's offer, we urge our shareholders to place their
confidence in our management's detailed and credible plan for sustainable future
value  creation."  Mr.  Dennler   continued:   "Our  standalone   forecasts  for
shareholder  returns outstrip SCOR's for the combined  business,  reflecting our
operational  strength and  potential  for  profitable  growth in the wake of our
recent  rating  upgrade  from  Standard & Poor's.  SCOR  wants to  deliver  that
potential  to its own  shareholders,  offering  in  exchange  a  volatile  share
currency  which could see  further  devaluation  from the risks  inherent in the
transaction.  To put it simply, our shareholders stand to score more by sticking
with Converium."

The  following  summarizes  the main  reasons  for the  Board's  recommendation.
Further details are provided in the Board report to be published in Neue Zurcher
Zeitung  and Le Temps  tomorrow  and,  after  close  of  trading,  available  on
www.converium.com.


The offer undervalues Converium

SCOR's offer does not fully reflect the long-term value of Converium's strategic
road map  announced  on February 28,  2007.  The Board of  Directors  and senior
management  of Converium  believe that  execution of the  Company's  road map to
generate a  sustainable  return on equity of 14% by 2009 will  create  long-term
shareholder  value in excess of SCOR's offer price. The recent Standard & Poor's
upgrade of the Company's  long-term  financial  strength rating to "A-" confirms
the low execution risks relating to Converium's standalone strategy.

                                       2


SCOR's offer price  represents  only a 12.3%  premium  compared with the closing
stock market price of Converium's shares on February 16, 2007, the day preceding
the announcement by SCOR of its acquisition of 32.9% of Converium's  outstanding
shares.

Reflecting the value-sensitive information publicly disclosed by Converium since
then,  the current value of the offer  represents a 0.4% discount to the closing
stock market price of Converium's shares on April 12, 2007.

Using  the  average  market  price  for  the  one-month   period   preceding  an
announcement,  the average premium observed in the most significant  unsolicited
public  offers  completed in  Switzerland  since 2005 is more than 50%,  whereas
SCOR's offer only represents a 16.0% premium.


Hostile offer carries significant business, integration and execution risks

SCOR's hostile approach is  unprecedented  in the reinsurance  arena. It entails
significant  business  and  integration  risks in terms  of staff  and  customer
retention which could mean a loss of up to USD 800 million in premium income:

     o    Most reinsurance  contracts contain change in control  provisions that
          might  successfully be enforced upon the  consummation of the offer. A
          key  example of this are the major  strategic  alliances  with  Global
          Aerospace  Underwriting  Managers Ltd.  (GAUM) and the Medical Defence
          Union  (MDU)  alone  account  for more than USD 361 million of premium
          income.

          GAUM's CEO, Tony Medniuk,  comments:  "Converium has been an important
          and highly valued partner for GAUM since 2001. Should this unsolicited
          offer be successful  the other  co-owners of the agency and members of
          the  pool  would  have  to  seriously   reassess   Converium's  future
          participation in the pool. SCOR should not consider any part of GAUM's
          business as automatically vesting to them."

          This view is echoed by Mike Saunders,  CEO of MDU: "Since 2000 the MDU
          and  its  members  have  benefited   significantly   from  a  mutually
          successful  joint  venture with  Converium due in no small part to the
          strong personal relationships developed between the companies. If SCOR
          is successful in its hostile offer for Converium,  the MDU will review
          the  relationship  in the  light of its right to  terminate  the joint
          venture following a change of control."

     o    The  hostility of the offer  carries  significant  business  risks:  a
          hostile takeover could increase attrition risk,  triggering  customers
          who want to diversify their reinsurance policies to defect.  Converium
          estimates  that this could drive a potential  premium  loss of USD 330
          million.

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     o    In addition,  SCOR's approach carries  significant  integration risks:
          its  hostility  may  trigger  an  exodus  at  every  level  of  senior
          management,  underwriters  and other valuable  specialists  which will
          amount in an additional potential premium loss of USD 110 million.

Finally,  the hostility of the offer  presents  major  execution  risks as it is
unlikely to foster a smooth and proper integration of both companies.


SCOR's shares weak acquisition currency

The offer  consideration  to be received by Converium  shareholders is uncertain
and will depend on the value of SCOR's shares at the time of the consummation of
the offer. SCOR's shares are a weak acquisition  currency, as evidenced by their
high volatility.  As the offer consideration  consists of 80% in SCOR shares and
20% in cash,  Converium  shareholders  will be  subject  to the risk of  further
volatility of SCOR's shares.  A significant  valuation  downside is presented by
the major business, integration and execution risks of the transaction.


Prospects of a combined entity are questionable

SCOR  anticipates  growing  the  combined  entity's  book of business at a lower
growth rate than that of Converium on a standalone  basis: SCOR anticipates that
the combined entity will grow at a rate of 7% per year while Converium  believes
that it would  grow as a  standalone  entity  at a rate of 17% per year over the
next two years based on regaining share of wallet of pre-downgrade  business and
acquiring new business.

SCOR  anticipates a return on tangible equity (includes a deduction for sizeable
intangibles,  such as  goodwill,  post  transaction)  of 13%  comparing  it with
Converium's return of equity target of 14% to be reached by 2009 through organic
growth.  Converium  estimates  SCOR's pro forma ROE  calculated  on a comparable
basis to that of Converium at around 11%.

Based on public information, SCOR estimates that the combined entity will barely
meet the capital  adequacy  ratio for a Standard & Poor's "A-" rated  company at
the end of 2007. This implies that the occurrence of severe natural catastrophes
in the second half of 2007 would  jeopardize the rating of the combined  entity,
whereas Converium  currently  possesses  material excess capital as a standalone
entity.


Concluding recommendation

Converium's Board of Directors therefore urges its shareholders to reject SCOR's
offer and place  their  faith in future  value  creation  from a team  which has
proven its ability to drive the business  forward.  It is a choice which favours
certainty  over  considerable  business,  execution  and  integration  risks and
preserves  value  rather  than  throwing  it away.  Those who want to score more
should allow  Converium's  management team to pursue its plan for value creation
to its exciting conclusion.

                                       4


First quarter results to be released on April 19, 2007

Converium  will release its first  quarter  2007  financial  results  before the
markets  open in Europe on Thursday,  April 19, 2007.  The release date has been
brought forward from May 8, 2007.

A webcast for the investment community and media will be held on the same day at
9.30 am Central European Time (CET).

The webcast can be accessed via the company's website www.converium.com. It will
be archived on our website at about noon time that day. The telephone  replay of
the conference  call will also be available one hour after the call for 24 hours
by dialing  +41 91 612 4330  (Europe),  +1 (1) 866 416 2558 (USA) or +44 (0) 207
108 6233 (UK) with access code: 336#.


Enquiries

Beat W. Werder                                  Marco Circelli
Head of Public Relations                        Head of Investor Relations
beat.werder@converium.com                       marco.circelli@converium.com

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
Officer
kai-uwe.schanz@converium.com                    inken.ehrich@converium.com

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


                                       5


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.

                                       6


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'.   The   specific
forward-looking  statements  cover,  among other  matters,  our combined  ratio,
return on equity and premium volume and expense reduction targets,  our plans to
use  capital  more  efficiently  and to  return  capital  to  shareholders,  the
reinsurance  market,  the Company's  operating  results,  the Company's dividend
policy,  the prospects for  improving our results,  investment  yield and market
share.   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.

                                       7


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: April 18, 2007

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