Document:

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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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Mountain Ridge/Liberty Mutual
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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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Mountain Ridge/Liberty Mutual
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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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                                                                    EXHIBIT 10.5

                      PLATINUM UNDERWRITERS HOLDINGS, LTD.
                             The Belvedere Building
                                69 Pitts Bay Road
                             Pembroke HM 08 Bermuda

                                             June 20, 2003

Gregory E. A. Morrison
42 Buttermere Road
London, Ontario Canada N6G4L1

Dear Gregory:

         I am writing this letter (the "Letter Agreement") to confirm the terms
and conditions of your employment with Platinum Underwriters Holdings, Ltd., a
Bermuda corporation ("Platinum") and Platinum Underwriters Bermuda, Ltd., a
Bermuda corporation ("Platinum Bermuda").

1.       Term of Employment.

         Your employment will commence on June 1, 2003 (the "Effective Date")
and, subject to termination as provided in Section 11, shall end on the third
anniversary of the Effective Date; provided that on the third anniversary of the
Effective Date and each anniversary thereafter, the term of your employment
shall automatically be extended by an additional year unless Platinum or you
give the other party written notice, at least 30 days prior to the applicable
anniversary of the Effective Date, that you or it does not want the term to be
so extended. Such employment period, as extended, shall hereinafter be referred
to as the "Term."

2.       Title and Duties.

         During the Term, you will serve as President and Chief Executive
Officer of Platinum and Chief Executive Officer of Platinum Bermuda and will
have such duties and responsibilities and power and authority as those normally
associated with such positions, plus any additional duties, responsibilities
and/or power and authority assigned to you by the Board of Directors of Platinum
(the "Board"). In addition, you will be the Chairman of the Board of all
Platinum subsidiaries. Platinum will use its best efforts to nominate you for
election to the Board at its 2003 annual meeting of shareholders.

3.       Base Salary.

         During the Term, Platinum will pay you a base salary (the "Base
Salary") at an annual rate of US$650,000 (the "Base Salary"), payable in
accordance with Platinum's payroll practices as in effect from time to time.
Your Base Salary may be reviewed from time to time by the Board for possible
merit increase.

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4.       Bonus.

         (a)      Sign-On Bonus. You will receive a one-time sign-on bonus of
                  US$150,000, payable within five (5) days following the signing
                  of this Letter Agreement.

         (b)      Annual Incentive. For the remainder of the 2003 fiscal year,
                  you will be paid a minimum annual bonus of US$650,000,
                  provided that you remain employed until December 31, 2003 (the
                  "Minimum Bonus"). During each fiscal year of the Term
                  thereafter, you will be eligible for an annual performance
                  bonus pursuant to the terms of Platinum's annual incentive
                  plan (the "Annual Bonus"). Your Annual Bonus will have an
                  incentive target equal to 100% of Base Salary (the "Target
                  Bonus") with the range of bonus payout to be from 0% to 200%
                  of Base Salary, depending upon the achievement of performance
                  criteria established under Platinum's annual incentive plan.
                  The Minimum Bonus and the Annual Bonus will generally be paid
                  following the end of the applicable fiscal year, part in cash
                  and part in restricted stock units or other equity incentives,
                  as determined by the Compensation Committee of the Board.

         (c)      Long-Term Incentive. Platinum currently intends to establish a
                  long-term incentive plan for its key employees, including its
                  Chief Executive Officer. The terms of such plan and the timing
                  of its implementation have not yet been established. If a
                  long-term plan is established by the Board, you will be a
                  participant in the plan.

5.       Share Option Grant.

         Effective as of May 13, 2003, you have been granted an option to
purchase 400,000 of Platinum's common shares under the terms of Platinum's 2002
Share Incentive Plan (the "Option Grant"). The Option Grant (i) has a term of
ten years from the date of grant, (ii) has an exercise price of US$26.00 per
share, the closing sales price of the Platinum common shares on the New York
Stock Exchange on the trading day immediately preceding the date of grant and
(iii) vests in equal annual installments on each of the first four anniversaries
of the date of grant, based on your continued employment with Platinum. The
specific terms of your Option Grant will be provided for in an option agreement
between you and Platinum that has been approved by the Compensation Committee
under the 2002 Share Incentive Plan, the form of which agreement is attached
hereto.

6.       Share Ownership.

         You agree to purchase from Platinum 20,000 of Platinum's common shares
at a purchase price of US$26.00 per share (the "Purchased Shares") within 60
days following the signing of this Letter Agreement. You agree to enter into a
purchase agreement in connection with such purchase containing representations,
warranties and covenants typical for such an agreement. You represent, warrant,
acknowledge and agree that (i) you have had the opportunity to ask questions of,
and receive information from, representatives of Platinum concerning Platinum
and your investment in Platinum, (ii) by reason of your business or financial
experience you are capable of evaluating information and data relating to
Platinum and the merits or risks of an investment in Platinum and of protecting
your own interest in connection with an investment in Platinum and that you are
able to bear the economic risk of such investment in Platinum, (iii) you are an
"accredited investor" as

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defined in Regulation D promulgated under the Securities Act of 1933, as amended
(the "Act"), (iv) you are purchasing the Purchased Shares for your own account,
for investment only, and not with a view to, or for resale in connection with,
any distribution thereof, (v) the Purchased Shares may not be sold, transferred,
pledged or otherwise disposed of without registration under the Act and
applicable state securities laws or in accordance with applicable exemptions
therefrom, (vi) any transfer of the Purchased Shares is subject to Platinum
receiving an opinion of counsel satisfactory to it, and (vii) the certificates
representing the Purchased Shares will bear legends referring to restrictions on
transferability and sale and a notation will be made on the appropriate records
of Platinum and Platinum's transfer agent so that transfers of the Purchased
Shares will not be effected on those records without compliance with those
restrictions. You acknowledge that the Board is considering adopting share
ownership requirements for senior executives of Platinum.

7.       Employee Benefits.

         During the Term, you and your eligible dependents will receive benefits
substantially similar to the employee benefit plans that are generally available
to senior executives of Platinum, subject to the terms and conditions of such
plans. The Board reserves the right to amend or terminate any employee benefit
plan at any time, and to adopt any new plan.

8.       Moving/Housing.

         Platinum will pay you $50,000 associated with your relocation to
Bermuda. Upon your establishment of a residence in Bermuda, you will be entitled
to reimbursement of your actual and reasonable housing and living expenses up to
US$25,000 per month (the "Monthly Reimbursement") during the Term.

9.       Perquisites.

         Platinum will reimburse you for reasonable dues and fees for a golf and
a health club membership during the Term, as well as such other perquisites and
fringe benefits as may be approved by the Compensation Committee of the Board
from time to time. Platinum will reimburse you for reasonable expenses
associated with the review of this Letter Agreement by your advisors. Platinum
will reimburse you for the reasonable school fees associated with the attendance
of your children at high schools in Bermuda.

10.      Business Expenses.

         During the Term, Platinum shall reimburse you for all reasonable
expenses and disbursements in carrying out your duties and responsibilities
under this Letter Agreement in accordance with Company policy for senior
executives as in effect from time to time.

11.      Termination of Employment.

         (a)      Termination for Good Reason or Without Cause. If you terminate
                  your employment during the Term for "Good Reason" (as defined
                  below) or if your employment is terminated during the Term by
                  Platinum without "Cause," (as defined below) you will receive,
                  beginning one month following the effective date of any such
                  termination, monthly salary continuation payments for the
                  "Severance Period" (as

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                  defined below) equal to one-twelfth (1/12) of the sum of (i)
                  100% of your then-current Base Salary and (ii) the greater of
                  (a) your then-current Target Bonus and (b) the amount of
                  Annual Bonus payable to you (without regard to equity-based
                  deferrals) for the fiscal year immediately preceding the year
                  during which the effective date of your termination of your
                  employment occurs (or, in the event such termination occurs
                  during 2003, the amount of your Minimum Bonus). For purposes
                  hereof, the Severance Period shall be the lesser of (1)
                  twenty-four (24) months, or (2) the number of full months
                  remaining in the Term on the effective date of termination of
                  employment; provided, however that the Severance Period shall
                  not be less than twelve (12) months. You will also be paid any
                  earned but unpaid Base Salary or other amounts (including
                  reimbursements expenses and any vested amounts or benefits
                  under Platinum's employee benefit plans or programs) accrued
                  or owing through the date of termination. The foregoing
                  payment will be conditioned upon you executing and honoring a
                  standard waiver and release of claims in favor of Platinum in
                  a form determined by Platinum. Any vested and unexercised
                  options to purchase Platinum's common shares held by you as of
                  the effective date of such termination will remain exercisable
                  for the greater of 45 days from such date or May 31, 2006
                  whichever is later. Any unvested options to purchase
                  Platinum's common shares and any unvested equity incentive
                  awards held by you as of the effective date of such
                  termination will be immediately forfeited.

         (b)      Termination Other than for Good Reason. If you terminate your
                  employment during the Term other than for Good Reason, you
                  will receive no further payments, compensation or benefits
                  under this Letter Agreement, except you will be eligible to
                  receive, upon the effectiveness of such termination, amounts
                  (including reimbursable expenses and any vested amounts or
                  benefits under Platinum's employee benefit plans or programs)
                  accrued or owing prior to the effectiveness of such
                  termination. Any vested and unexercised options to purchase
                  Platinum's common shares held by you as of the effective date
                  of such termination will remain exercisable for 45 days from
                  such date. Any unvested options to purchase Platinum's common
                  shares and any unvested equity incentive awards held by you as
                  of the effective date of such termination will be immediately
                  forfeited.

         (c)      Termination for Cause. If your employment is terminated by
                  Platinum during the Term for Cause, you will receive no
                  further payments, compensation or benefits under this Letter
                  Agreement, except you will be eligible to receive, upon the
                  effectiveness of such termination, amounts (including
                  reimbursable expenses and any vested amounts or benefits under
                  Platinum's employee benefit plans or programs) accrued or
                  owing prior to the effectiveness of your termination. All
                  vested and unvested options to purchase Platinum's common
                  shares and other equity incentive awards held by you as of the
                  effective date of such termination will be immediately
                  forfeited.

         (d)      Death or Disability. Upon the termination of your employment
                  during the Term on account of your death or Disability, you or
                  your beneficiaries will receive (i) any unpaid Base Salary
                  through the date of termination plus a pro-rata portion
                  through the date of termination of your Target Bonus (or
                  Minimum Bonus, if applicable) for

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                  the year of termination, (ii) all other unpaid amounts
                  (including reimbursable expenses and any vested amounts or
                  benefits under Platinum's employee benefit plans or programs)
                  accrued or owing prior to the effectiveness of such
                  termination. In addition, the unvested portion of any
                  outstanding options to purchase Platinum's common shares or
                  other equity incentive awards held by you shall fully vest as
                  of the date of such termination and, along with any previously
                  vested grants, will be exercisable for one year from the
                  effectiveness of such termination.

         (e)      Definitions.

                           (i)      Cause. For purposes of this Letter
                                    Agreement, "Cause" means (i) your willful
                                    and continued failure to substantially
                                    perform your duties hereunder; (ii) your
                                    conviction of, or plea of guilty or nolo
                                    contendere to, a felony or other crime
                                    involving moral turpitude; or (iii) your
                                    engagement in any malfeasance or fraud or
                                    dishonesty of a substantial nature in
                                    connection with your position with Platinum
                                    or its subsidiaries, or other willful act
                                    that materially damages the reputation of
                                    Platinum or its subsidiaries; provided,
                                    however, no such act, omission or event
                                    shall be treated as "Cause" under this
                                    Letter Agreement unless you have been
                                    provided a detailed, written statement of
                                    the basis for Platinum's belief that such
                                    act, omission or event constitutes "Cause"
                                    and have had at least a thirty (30) day
                                    period to take corrective action. For
                                    purposes of this Section, no act or failure
                                    to act will be considered "willful" unless
                                    it is done, or omitted to be done, in bad
                                    faith and without reasonable belief that the
                                    action was in the best interests of
                                    Platinum.

                           (ii)     Good Reason. For purposes of this Letter
                                    Agreement, "Good Reason" means (i) Platinum
                                    reduces your Base Salary or your Target
                                    Bonus (or Minimum Bonus, if applicable)
                                    without your express written consent; (ii)
                                    Platinum reduces the scope of your duties,
                                    responsibilities or authority without your
                                    express written consent; (iii) Platinum
                                    requires you to report to anyone other than
                                    the Board; (iv) Platinum requires you to be
                                    principally based other than in Platinum's
                                    offices in Bermuda; (v) Platinum breaches
                                    any other material provision of this Letter
                                    Agreement; and (vi) Platinum elects not to
                                    extend the term of this Letter Agreement;
                                    provided, however, that if you voluntarily
                                    consent to any reduction or change described
                                    above in lieu of exercising your right to
                                    resign for Good Reason and deliver such
                                    consent to Platinum in writing, then such
                                    reduction, transfer or change shall not
                                    constitute "Good Reason" hereunder, but you
                                    shall have the right to resign for Good
                                    Reason under this Letter Agreement as a
                                    result of any subsequent reduction described
                                    above.

                           (iii)    Disability. For purposes of this Letter
                                    Agreement, "Disability" means a termination
                                    of your employment by Platinum if you have
                                    been rendered incapable of performing your
                                    duties to Platinum by reason of any
                                    medically determined physical or mental
                                    impairment that can be expected

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                                    to result in death or that can be expected
                                    to last for a period of either (i) six or
                                    more consecutive months from the first date
                                    of your absence due to the disability or
                                    (ii) nine or more months during any
                                    twelve-month period.

12.      Covenants.

         In exchange for the remuneration outlined above, in addition to
providing service to Platinum as set forth in this Letter Agreement, you agree
to the following covenants:

         (a)      Confidentiality. During the period of your employment and
                  following any termination of your employment for any reason,
                  you will keep confidential any trade secrets and confidential
                  or proprietary information of Platinum (and its subsidiaries
                  and affiliates) which are now known to you or which hereafter
                  may become known to you as a result of your employment or
                  association with Platinum and will not at any time, directly
                  or indirectly disclose any such information to any person,
                  firm or corporation, or use the same in any way other than in
                  connection with the business of Platinum (or its subsidiaries
                  or affiliates) during, and at all times after, the termination
                  of your employment. For purposes of this Letter Agreement,
                  "trade secrets and confidential or proprietary information"
                  means information unique to Platinum (or its subsidiaries or
                  affiliates) which has a significant business purpose and is
                  not known or generally available from sources outside Platinum
                  (or its subsidiaries or affiliates) or typical of industry
                  practice, but shall not include any of the foregoing (i)
                  information that becomes a matter of public record or is
                  published in a newspaper, magazine or other periodical
                  available to the general public, other than as a result of any
                  act or omission of you or (ii) information that is required to
                  be disclosed by any law, regulation or order of any court or
                  regulatory commission, department or agency, provided that you
                  give prompt notice of such requirement to Platinum (or its
                  subsidiaries or affiliates), as appropriate, to enable
                  Platinum (or its subsidiaries or affiliates), as appropriate,
                  to seek an appropriate protective order or confidential
                  treatment.

         (b)      Non-Competition. You further covenant that during the period
                  of your employment with Platinum and for the fifteen month
                  period following termination of your employment for any
                  reason, you will not, without the express written approval of
                  Platinum, anywhere where Platinum (or its subsidiaries of
                  affiliates) has engaged in business during the term of your
                  employment with Platinum, for yourself or on behalf of any
                  other person, partnership, company or corporation, directly or
                  indirectly, acquire any financial or beneficial interest, be
                  employed by, or own, manage, operate or control any entity
                  which is primarily engaged in the reinsurance business;
                  provided, however, you may have an interest in up to 2% of the
                  capital stock of a corporation whose capital stock is traded
                  publicly.

         (c)      Non-Solicitation. You further covenant that during the term of
                  your employment with Platinum and during the fifteen month
                  period following termination of your employment for any
                  reason, you will not, directly or indirectly, hire, or cause
                  to be hired by an employer with whom you may ultimately become
                  associated, any senior executive of Platinum (or its
                  subsidiaries or affiliates) at the time of termination of

                                       6

<PAGE>

                  your employment with Platinum (defined for such purposes to
                  include executives that report directly to you or that report
                  directly to such executives that report directly to you).

         (d)      Enforcement. You acknowledge that if you breach any provision
                  of this Section 12, Platinum (or its subsidiaries or
                  affiliates) will suffer irreparable injury. It is therefore
                  agreed that Platinum (or its subsidiaries or affiliates) shall
                  have the right to enjoin any such breach, without posting any
                  bond, if permitted by a court of the applicable jurisdiction.
                  You hereby waive the adequacy of a remedy at law as a defense
                  to such relief. The existence of this right to injunctive, or
                  other equitable relief, shall not limit any other rights or
                  remedies which Platinum (or its subsidiaries or affiliates)
                  may have at law or in equity including, without limitation,
                  the right to monetary, compensatory and punitive damages. You
                  acknowledge and agree that the provisions of this Section 12
                  are reasonable and necessary for the successful operation of
                  Platinum. In the event an arbitrator or a court of competent
                  jurisdiction determines that you have breached your
                  obligations in any material respect under this Section 12,
                  Platinum, in addition to pursuing all available remedies under
                  this Letter Agreement, at law or otherwise, and without
                  limiting its right to pursue the same shall cease all payments
                  to you under this Letter Agreement. If any provision of this
                  Section 12 is determined by a court of competent jurisdiction
                  to be not enforceable in the manner set forth in this Letter
                  Agreement, you and Platinum agree that it is the intention of
                  the parties that such provision should be enforceable to the
                  maximum extent possible under applicable law. If any
                  provisions of this Section 13 are held to be invalid or
                  unenforceable, such invalidation or unenforceability shall not
                  affect the validity or enforceability of any other provision
                  of this Letter Agreement (or any portion thereof).

13.      Representations. By signing this Letter Agreement where indicated
         below, you represent that you are not subject to any employment
         agreement or noncompetition agreement that would prevent you from
         performing your obligations under this Letter Agreement nor that could
         subject Platinum to any present or future liability or obligation to
         any third party as a result of the execution of this Letter Agreement
         and your appointment to the positions with Platinum described above.

14.      Miscellaneous Provisions.

         (a)      This Letter Agreement may not be amended or terminated without
                  the prior written consent of you and Platinum.

         (b)      This Letter Agreement may be executed in any number of
                  counterparts which together will constitute but one agreement.

         (c)      This Letter Agreement will be binding on and inure to the
                  benefit of our respective successors and, in your case, your
                  heirs and other legal representatives. Other than as provided
                  herein, the rights and obligations described in this Letter
                  Agreement may not be assigned by either party without the
                  prior written consent of the other party.

                                       7

<PAGE>

         (d)      Subject to Section 12(d) of this Letter Agreement, all
                  disputes arising under or related to this Letter Agreement
                  will be settled by arbitration under the Commercial
                  Arbitration Rules of the American Arbitration Association then
                  in effect as the sole and exclusive remedy of either party.
                  Such arbitration shall be held in New York City. Any judgment
                  on the award rendered by such arbitration may be entered in
                  any court having jurisdiction over such matters. Each party's
                  costs and expenses of such arbitration, including reasonable
                  attorney fees and expenses, shall be borne by such party,
                  unless you are, in whole, and not in part, the prevailing
                  party in the award entered in such arbitration, in which case,
                  all such costs and expenses shall be borne by Platinum.

         (e)      All notices under this Letter Agreement will be in writing and
                  will be deemed effective when delivered in person, or five (5)
                  days after deposit thereof in the mails, postage prepaid, for
                  delivery as registered or certified mail, addressed to the
                  respective party at the address set forth below or to such
                  other address as may hereafter be designated by like notice.
                  Unless otherwise notified as set forth above, notice will be
                  sent to each party as follows:

                  Gregory Morrison, to:

                  The address maintained in Platinum's records

                  Platinum, to:

                  Platinum Underwriters Holdings, Ltd.
                  The Belvedere Building
                  69 Pitts Bay Road
                  Pembroke HM 08, Bermuda
                  P.O. Box HM 3012
                  Hamilton HM MX, Bermuda
                  Attention: General Counsel

         In lieu of personal notice or notice by deposit in the mail, a party
may give notice by confirmed telegram, telex or fax, which will be effective
upon receipt.

         (f)      This Letter Agreement will be governed by and construed and
                  enforced in accordance with the laws of the State of New York
                  without reference to rules relating to conflict of laws.

         (g)      This Letter Agreement supercedes any inconsistent provisions
                  of any plan or arrangement that would otherwise be applicable
                  to you to the extent such provisions would limit any rights
                  granted to you hereunder or expand any restrictions imposed on
                  you hereby.

         This Letter Agreement is intended to be a binding obligation upon
Platinum and yourself. If this Letter Agreement correctly reflects your
understanding, please sign and return one copy to me for Platinum's records.

                                       8

<PAGE>

                                       Platinum Underwriters Holdings, Ltd.

                                       By: /s/ Michael E. Lombardozzi
                                           ------------------------------------
                                       Michael E. Lombardozzi
                                       Executive Vice President, General Counsel
                                       and Corporate Secretary

The above Letter Agreement correctly reflects our understanding, and I hereby
confirm my agreement to the same.

/s/ Gregory E. A. Morrison
--------------------------------
Gregory E. A. Morrison

Dated as of June 20, 2003

                                       9

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