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                                                                    EXHIBIT 10.4

                            AGGREGATE EXCESS OF LOSS
                             RETROCESSION AGREEMENT

                                     Between

                     Platinum Underwriters Reinsurance, Inc.

                                       And

                        Mountain Ridge Insurance Company

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Mountain Ridge/Liberty Mutual
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                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
ARTICLE                                            PAGE
<S>                                                <C>
I                        COMMENCEMENT AND
                         TERMINATION                 1

II                       DEFINITIONS                 1

III                      COVER                       2

IV                       TERRITORY                   2

V                        PREMIUM                     2

VI                       REPORTS AND REMITTANCES     3

VII                      ERRORS AND OMISSIONS        3

VIII                     ACCESS TO RECORDS           3

IX                       OFFSET                      4

X                        ARBITRATION                 4

XI                       CURRENCY                    5

XII                      INSOLVENCY                  5

XIII                     ENTIRE AGREEMENT            6

XIV                      SEVERABILITY                6

XV                       GOVERNING LAW               7
</TABLE>

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                            AGGREGATE EXCESS OF LOSS
                             RETROCESSION AGREEMENT
                    (Hereinafter referred to as "Agreement")

This Agreement made and entered into by and between Platinum Underwriters
Reinsurance, Inc. (hereinafter called the "Retrocessionaire") and Mountain Ridge
Insurance Company (hereinafter called the "Retrocedant").

WITNESSETH:

In consideration of the mutual covenants hereinafter contained and upon the
terms and conditions hereinafter set forth, the parties hereto agree as follows:

The retrocessionaire hereby reinsures the Retrocedant to the extent and on the
terms and conditions and subject to the exceptions and limitations hereinafter
set forth and nothing hereinafter shall in any manner create any obligations or
establish any rights against the Retrocessionaire in favor of any third parties
or any persons not parties to this Agreement, including the Underlying Reinsured
under the Underlying Agreements as hereafter defined.

                                    ARTICLE I

COMMENCEMENT AND TERMINATION

This agreement is coextensive and coterminous with the Underlying Agreement and
shall remain in full force and effect until all obligations and liabilities
incurred by Retrocedent under the Underlying Agreement are fully performed and
discharged and after the Underlying Reinsured under the Underlying Agreement has
satisfied its obligations to the Retrocedent. The Retrocessionaire shall then be
fully discharged and released of all obligations and liabilities hereunder.

                                   ARTICLE II

DEFINITIONS

  a)     "Quarterly Reports" as used herein, shall have the meaning provided in
         the Underlying Agreement in the SETTLEMENTS & REPORTS Article.

  b)     "Settlement(s)" as used herein, shall have the meaning defined in the
         SETTLEMENTS & REPORTS Article.

  c)     "Maintenance Fees" as used herein, shall have the meaning provided in
         the Underlying Agreement.

  d)     "Ultimate Net Losses" as used herein, shall have the same meaning as
         the "Aggregate Net Losses" in the Underlying Agreement.

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  e)     "Underlying Agreement" as used herein, shall refer to the Whole Account
         Aggregate Excess of Loss Reinsurance Agreement entered into by and
         between Liberty Mutual Insurance Company (therein referred to as the
         "Company" herein referred to as "Underlying Reinsured") and to which
         the Retrocedent is a party (therein as "Reinsurer") incepted on January
         1, 2001. The Underlying Agreement is attached hereto and identified as
         APPENDIX I.

  f)     "Funds Withheld Account" as used herein, shall have the meaning
         provided in the Underlying Agreement.

                                   ARTICLE III

COVER

Subject to the terms and conditions of this Agreement, the Retrocessionaire will
indemnify the Retrocedent for 100% of Aggregate Ultimate Net Loss paid by the
Retrocedent under the Underlying Agreement in excess of the Funds Withheld
Account.

Ultimate Net Losses recoverable under this Agreement shall be reduced by an
amount equal to, if positive,

         -        the Maintenance Fees received by the Retrocedant on or after
                  January 1, 2003, less

         -        the letter of credit cost incurred by the Retrocedant on or
                  after January 1, 2003 under the Underlying Agreement.

All exclusions contained in the Underlying Agreement are incorporated herein by
reference.

                                   ARTICLE IV

TERRITORY

This Agreement shall apply to losses occurring within the territorial limits of
the Underlying Agreement.

                                   ARTICLE V

PREMIUM

In consideration of the reinsurance provided under this Agreement, the
Retrocedent shall pay to the Retrocessionaire a flat premium of $100,000. The
Premium shall be payable within thirty (30) days upon signing this Agreement.

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                                   ARTICLE VI

REPORTS AND REMITTANCES

  a)     The Retrocedent agrees, within fifteen (15) days after receipt of
         Quarterly Reports, from the Underlying Reinsured, it will advise the
         Retrocessionaire of Ultimate Net Losses incurred by Retrocedent
         pursuant to the Underlying Agreement and to furnish the
         Retrocessionaire with such particulars and estimates regarding same as
         are in the possession of the Retrocedent.

  b)     Within fifteen (15) days after receipt of Retrocedent's request for an
         amount equal to the Ultimate Net Losses in excess of the Retention that
         have been paid or are immediately due and payable since the last report
         the Retrocessionaire shall remit said amount ("Settlement(s)") to the
         Retrocedent. All salvages, subrogations, recoveries or reimbursements
         recovered or received subsequent to a Settlement under this Agreement
         shall be applied as if recovered or received prior to the Settlement
         and all necessary adjustments shall be made by the parties hereto.
         Subrogation and salvage shall always be applied in the reverse order of
         the parties' priority in the Settlement; i.e. the Retrocessionaire will
         be reimbursed before reimbursing the Retrocedent for its portion of the
         Settlement under its retention.

                                   ARTICLE VII

ERRORS AND OMISSIONS

Clerical errors or omissions on the part of the Retrocedent shall not invalidate
the reinsurance under this Agreement, provided such errors or omissions are
corrected promptly under discovery thereof, but the liability of the
Retrocessionaire under this Agreement shall in no event exceed the limits
specified herein.

                                  ARTICLE VIII

ACCESS TO RECORDS

The Retrocedent shall place at the disposal of the Retrocessionaire at all
reasonable times, and the Retrocessionaire shall have the right to inspect
through its designated representatives, during the term of this Agreement and
thereafter, all books, records and papers of the Retrocedent in connection with
any reinsurance hereunder, or the subject matter hereof. This right shall
survive termination of this Agreement and shall continue as long as either party
has any rights or obligations under this Agreement.

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                                  ARITICLE IX

OFFSET

Each party hereto shall have and may exercise at any time and from time to time
the right to offset any balance or balances whether on account of premiums,
interest, or on account of losses or otherwise due from each party to the other
party hereto under this Agreement and the party asserting the right to offset
shall have and may exercise such right whether the balance or balances due or to
become due to such party from the other are on account of premiums, interest, or
on account of losses or otherwise and regardless of the capacity whether as
assuming the reinsurer or as ceding insurer in which each party hereto, offset
shall only be allowed in accordance with the applicable law of the state having
jurisdiction over the insolvency.

                                    ARTICLE X

ARBITRATION

As a condition precedent to any right of action hereunder, any dispute arising
out of this Agreement, whether arising before or after termination, shall be
submitted to the decision of a board of arbitration composed of two arbitrators
and an umpire, meeting in New York, New York unless otherwise agreed.

The members of the board of arbitration shall be active or retired,
disinterested officials of insurance or reinsurance companies. Each party shall
appoint its arbitrator, and the two arbitrators shall choose an umpire before
instituting the hearing. If the respondent fails to appoint its arbitrator
within four weeks after being requested to do so by the claimant, the latter
shall also appoint the second arbitrator. If the two arbitrators fail to agree
upon the appointment of an umpire within four weeks after their nominations,
each of them shall name three, of whom the other shall decline two, and the
decision shall be made by drawing lots.

The claimant shall submit its initial brief within 20 days from appointment of
the umpire. The respondent shall submit its brief within 20 days thereafter, and
the claimant may submit a reply brief within 10 days after filing of the
respondent's brief.

The board shall make its decision with regard to the custom and usage of the
insurance and reinsurance business. The board shall issue its decision in
writing based upon a hearing in which evidence may be introduced without
following strict rules of evidence, but in which cross-examination and rebuttal
shall be allowed. The board shall make its decision within 60 days following the
termination of the hearings unless the parties consent to an extension. The
majority decision of the board shall be final and binding upon all parties to
the proceeding. Judgment may be entered upon the award of the board in any court
having jurisdiction thereof.

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Each party shall bear the expense of its own arbitrator and shall jointly and
equally bear with the other party the expense of the umpire. The remaining costs
of the arbitration proceedings shall be allocated by the board.

It is agreed that the jurisdiction of the arbitrators to make or render any
decision or award shall be limited by the limit of liability expressly
hereinbefore set forth, and that the arbitrators shall have no jurisdiction to
make any decision or render any award exceeding such expressly stated limit of
liability of the Reinsurer.

                                   ARTICLE XI

CURRENCY

All amounts due to either party hereunder shall be payable in United States
currency.

Amounts paid or received by the Company in any other currency shall be converted
to United States Dollars at the rate of exchange at the date such transaction is
entered on the books of the Company.

                                   ARTICLE XII

INSOLVENCY

In the event of the insolvency of the Company, reinsurance hereunder shall be
payable by the Reinsurer on the basis of the liability of the Company under any
policy or contract reinsured without diminution because of the insolvency of the
Company. It is agreed, however, that the liquidator or receiver or statutory
successor of the insolvent Company shall give written notice of the pendency of
a claim against the insolvent Company on the policy reinsured within a
reasonable time after such claim is filed in the insolvency proceeding and that
during the pendency of such claim the Reinsurer may investigate such claim and
interpose, at their own expense, in the proceeding where such claim is to be
adjudicated any defense or defenses which they may deem available to the Company
or its liquidator or receiver or statutory successor. The expense thus incurred
by the Reinsurer shall be chargeable, subject to court approval, against the
insolvent Company as part of the expense of liquidation to the extent of a
proportionate share of the benefit, which may accrue to the Company solely as a
result of the defense undertaken by the Reinsurer.

The reinsurance shall be payable by the Reinsurer directly to the Company or to
its liquidator, receiver or statutory successor, except as provided by Section
4118 of the New York Insurance Law or except (a) where the Contract specifically
provides another payee of such reinsurance in the event of the insolvency of the
Company or (b) where the Reinsurer with the consent of the direct insured or
insureds have assumed such policy obligations of the Company as direct
obligations of the Reinsurer to the payees under such policies and in
substitution for the obligations of the Company to such payees.

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                                  ARTICLE XIII

ENTIRE AGREEMENT

This Agreement embodies the entire agreement between the parties as to the
subject matter hereof. No waiver, modification, variation, change or amendment
to this Agreement will be binding on either party unless reduced to writing
signed by a duly authorized officer of each party.

                                   ARTICLE XIV

SEVERABILITY

If any provision of this Agreement shall be rendered illegal or unenforceable by
the laws, regulations or public policy of any state, such provision shall be
considered void in such state, but this shall not affect the validity or
enforceability of any other provision of this Agreement or the enforceability of
such provision in any other jurisdiction.

                                   ARTICLE XV

GOVERNING LAW

This Agreement and any modification hereof in writing by endorsement or
otherwise shall be governed in all respects, including but not limited to
performance, administration and interpretation, in accordance with the laws of
Vermont.

IN WITNESS HEREOF the parties hereto have caused this Agreement to be executed
in duplicate by their duly authorized representatives.

On this 11th day of June, 2003

By: /s/ Mark Wigmore              Attest: /s/ Angela Kinamore
   -----------------------                ---------------------

Title: President, Mountain Ridge Insurance Co.

and on this 11th day of June, 2003

By: /s/ Mangyu Hur                Attest: /s/ Gary French
    ---------------------                 ---------------------

Title: Vice President, Platinum Underwriters Reinsurance Inc.

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