Exhibit 10.4

MARKET SHARE UNIT AWARD AGREEMENT
Platinum Underwriters Holdings, Ltd.
2010 Share Incentive Plan

This MARKET SHARE UNIT AWARD AGREEMENT (this “Award Agreement”) made as of this
       day of      , 20       (the “Date of Grant”) between Platinum
Underwriters Holdings, Ltd., a Bermuda company (the “Company”), and        (the
“Participant”), is made pursuant to the terms of the Company’s 2010 Share
Incentive Plan or any successor plan (the “Plan”) and, if applicable, the
Company’s Section 162(m) Performance Incentive Plan or any successor plan.

Section 1. Definitions.

(a) Capitalized terms used herein but not defined shall have the meanings set
forth in the Plan.

(b) For purposes of this Award Agreement,

(i) “Cause” means: (1) the willful and continued failure of the Participant to
substantially perform his or her duties with the Company; (2) the Participant’s
conviction of, or plea of guilty or nolo contendere to, a felony or other crime
involving moral turpitude; (3) the Participant’s engagement in any malfeasance
or fraud or dishonesty of a substantial nature in connection with his or her
position with the Company or any of its subsidiaries, or other willful act that
materially damages the reputation of the Company or any of its subsidiaries;
(4) the Participant’s breach of the restrictive covenants in any option or other
award agreement between him or her and the Company; or (5) the Participant’s
sale, transfer or hypothecation of Common Shares of the Company in violation of
the Share Ownership Guidelines adopted by the Board of Directors of the Company;
provided, however, that no such act, failure to act or event shall be treated as
“Cause” unless the Participant has been provided a detailed, written statement
of the basis for the Company’s belief that such act, failure to act or event
constitutes “Cause” and has had at least thirty (30) days after receipt of such
statement to cure such act, failure to act or event. For purposes hereof, no act
or failure to act will be considered “willful” unless it is done, or failed to
be done, in bad faith, and without reasonable belief that the act or failure to
act was in the best interest of the Company.

(ii) “Good Reason” means the occurrence of any of the following events without
the Participant’s express written consent: (1) the Company reduces the
Participant’s base salary or the target for the Participant’s annual bonus;
(2) the Company reduces the scope of the Participant’s duties, responsibilities
or authority (including reporting responsibilities); (3) any requirement of the
Company that the Participant be principally based in any location other than the
location in which the Participant is currently principally based; or (4) a
breach by the Company of any of the material provisions of any employment
agreement between the Participant and the Company; provided, however, that if
the Participant voluntarily consents to any reduction or change described above
in lieu of exercising his or her right to resign for “Good Reason” and delivers
such consent to the Company in writing, then such reduction or change shall not
constitute “Good Reason” hereunder, but the Participant shall have the right to
resign for “Good Reason” as a result of any subsequent reduction or change
described above. Notwithstanding the foregoing, no act, failure to act or event
that is capable of being cured by the Company shall be treated as “Good Reason”
unless the Company has been provided a detailed, written statement of the basis
of the Participant’s belief that such act, failure to act or event constitutes
“Good Reason” and has had at least thirty (30) days after receipt of such
statement to cure such act, failure to act or event.

(iii) “Disability” shall have the meaning set forth in Section 409(a)(2)(C) of
the Code.

Notwithstanding the foregoing, in the event that the Participant is a party to
an employment agreement with the Company that defines Cause, Good Reason or
Disability, such definition will apply to the Participant for purposes of this
Award Agreement rather than the definition set forth above.

Section 2. Share Unit Award. The Company hereby grants to the Participant a
Share Unit Award of        share units under the Plan (the “Share Units”).

Section 3. Vesting Requirements and Forfeiture.

(a) General. The Share Units shall fully vest on the third anniversary of the
Date of Grant (the “Scheduled Vesting Date”), provided that the Participant
continues to be employed by the Company or one of its subsidiaries through the
Scheduled Vesting Date.

(b) Termination of Employment.

(i) If the Participant’s employment is terminated without Cause, for Good Reason
or upon the Participant’s retirement from the Company or any of its subsidiaries
with the consent of the Committee in its sole and absolute discretion (each an
“Employment Termination”) prior to the Scheduled Vesting Date or the vesting
date in the event of a Change in Control, death or Disability (as determined
below), then the Share Units shall immediately and fully vest on the effective
date of such Employment Termination (“Employment Termination Vesting Date”).

(ii) If the Participant’s employment is terminated for Cause, the Company may
require the Participant (1) to forfeit the Share Units, which shall then be
cancelled by the Company, and (2) to return to the Company any or all of the
Common Shares (and cash reflecting dividend equivalent rights) paid to the
Participant in respect of the Share Units, in such manner and on such terms and
conditions as may be required by the Company.

(c) Change in Control, Death or Disability. If there is a Change in Control of
the Company or if the Participant’s employment is terminated due to the
Participant’s death or Disability prior to the Scheduled Vesting Date or the
Employment Termination Vesting Date, then the Share Units shall immediately and
fully vest on the effective date of such Change in Control, death or Disability.

(d) Breach of Restrictive Covenants.

(i) If the Participant breaches Section 7(a) prior to the vesting of the Share
Units, the Company may require the Participant to forfeit the Share Units, which
shall then be cancelled by the Company.

(ii) If the Participant breaches Section 7(b) or any covenant not to compete
with the Company or any of its subsidiaries to which the Participant is or
becomes subject (a “Non-Compete Covenant”) at any time, the Company may require
the Participant (1) to forfeit the Share Units, which shall then be cancelled by
the Company, and (2) to return to the Company any or all of the Common Shares
(and cash reflecting dividend equivalent rights) paid to the Participant in
respect of the Share Units, in such manner and on such terms and conditions as
may be required by the Company.

Section 4. Payment of Award.

(a) Payment. This Share Unit Award shall be payable in that number of Common
Shares determined by multiplying the number of Share Units by the Performance
Multiplier. For purposes of this Award Agreement, the “Performance Multiplier”
shall be as follows:

(i) In the case of a Share Unit Award that vests on a Scheduled Vesting Date or
on an Employment Termination Vesting Date, the Performance Multiplier shall be
the average of the closing prices of the Common Shares on the New York Stock
Exchange or, if the Common Shares are not traded on the New York Stock Exchange,
such other exchange or securities market on which the Common Shares are traded
(the “Exchange”) for the twenty trading days ending on the last day of the
fiscal quarter immediately preceding the third anniversary of the Date of Grant
divided by the average of the closing prices of the Common Shares on the
Exchange for the twenty trading days ending on the last day of the fiscal
quarter immediately preceding the Date of Grant (the denominator, the “Initial
Share Price”);

(ii) In the case of a Share Unit Award that vests on death or Disability, the
Performance Multiplier shall be the average of the closing prices of the Common
Shares on the Exchange for the twenty trading days ending on the last day of the
fiscal quarter in which such death or Disability occurs divided by the Initial
Share Price; and

(iii) In the case of a Share Unit Award that vests on a Change in Control, the
Performance Multiplier shall be the average of the closing prices of the Common
Shares on the Exchange for the twenty trading days ending on the day immediately
preceding the effective date of such Change in Control divided by the Initial
Share Price.

Notwithstanding the foregoing, (1) the maximum number of Common Shares payable
in respect of the Share Units under this Share Unit Award shall be 150% of the
Share Units and (2) no Common Shares shall be payable in respect of the Share
Units under this Share Unit Award if the Performance Multiplier is less than
50%. This Share Unit Award will be paid as soon as practicable following the
last day used to determine the numerator of the Performance Multiplier in
Sections 4(a)(i), 4(a)(ii) or 4(a)(iii), as applicable (the “Last Day”), the
date that the Share Units fully vest, and, other than in the case of a Change in
Control, death or Disability, the date that the Committee shall have certified
the performance results governing this Share Unit Award, but in all events prior
to the March 15 of the calendar year following the year in which the Last Day
occurs. In the event that the Common Shares were not traded on an Exchange
during any period or portion thereof used in the determination of a Performance
Multiplier hereunder, the Board of Directors of the Company shall determine in
good faith such Performance Multiplier in whatever manner it considers
appropriate.

(b) Fractional Shares. No fractional Common Share shall be issued upon the
payment of this Share Unit Award. Any such fractional Common Share to which the
Participant would otherwise be entitled hereunder shall be rounded up to one
Common Share, which shall be included in the payment of Common Shares to the
Participant in respect of the Share Units.

(c) Dividend Equivalent Rights. Dividend equivalent rights shall be deemed to
accumulate on the Share Units under this Share Unit Award from the Date of
Grant. Accordingly, upon the payment of Common Shares to the Participant in
respect of the Share Units in accordance with this Section 4, the Participant
shall receive a payment in cash equal to the dividends that would have been paid
on such Common Shares if they had been outstanding since the Date of Grant.

(d) Withholding. The payment in respect of the Share Units shall be made to the
Participant after deduction of applicable withholding taxes in the amount
determined by the Company, which shall be withheld at the applicable
supplemental wage withholding rate, or such other rate as determined by the
Company, provided that such amount shall not exceed the Participant’s estimated
federal, state and local tax obligation with respect to payment in respect of
the Share Units. In lieu of the foregoing, the Company may allow the Participant
to pay the applicable withholding taxes to the Company in such other form as
approved by the Company.

Section 5. Restrictions on Transfer. No portion of the Share Units may be sold,
assigned, transferred, encumbered, hypothecated or pledged by the Participant,
other than to the Company as a result of forfeiture of the Share Units as
provided herein.

Section 6. Limitation of Rights. The Participant shall not have any privileges
of a shareholder of the Company with respect to the Share Units. Nothing in this
Award Agreement shall confer upon the Participant any right to continue as an
employee of the Company or any subsidiary or to interfere in any way with any
right of the Company to terminate the Participant’s employment at any time.

Section 7. Restrictive Covenants. The effectiveness of this Award Agreement is
conditioned upon the Participant honoring the following restrictive covenants
(the “Restrictive Covenants”). These Restrictive Covenants are not intended to
amend or supersede the terms of any noncompetition or other restrictive covenant
agreed to between the Company and the Participant or to which the Participant is
subject.

(a) Nondisclosure of Confidential Information. The Participant acknowledges that
during the course of the Participant’s employment with the Company and/or its
subsidiaries (collectively, the “Companies”) the Participant has had or will
have access to and knowledge of certain information that the Companies consider
confidential, and that the release of such information to unauthorized persons
would be extremely detrimental to the Companies. As a consequence, the
Participant hereby agrees and acknowledges that the Participant owes a duty to
the Companies not to disclose, and agrees that without the prior written consent
of the Company, at any time following the date hereof, either during or after
the Participant’s employment with any of the Companies, the Participant will not
communicate, publish or disclose, to any person anywhere or use, any
Confidential Information (as hereinafter defined), except as may be necessary or
appropriate to conduct the Participant’s duties to the Companies (provided the
Participant is acting in good faith and in the best interests of the Companies)
or as may be required by law or judicial process. The Participant will use best
efforts at all times to hold in confidence and to safeguard any Confidential
Information from falling into the hands of any unauthorized person. The
Participant will return to the Companies all Confidential Information in the
Participant’s possession or under the Participant’s control whenever any of the
Companies shall so request, and in any event will promptly return all such
Confidential Information if the Participant’s relationship with the Companies is
terminated for any or no reason and will not retain any copies thereof. For
purposes hereof, the term “Confidential Information” shall mean any information
used by or belonging or relating to the Companies that is not known generally to
the industry in which the Companies are, or may be, engaged and which the
Companies maintain on a confidential basis, including, without limitation, any
and all trade secrets and proprietary information, information relating to the
business and services, any employee information, customer lists and records,
business processes, procedures or standards, know-how, manuals, business
strategies, records, financial information, in each case, whether or not reduced
to writing or stored electronically, as well as any information that the
Companies advise the Participant should be treated as confidential.

(b) Non-Solicitation and Non-Hire of Employees. The Participant agrees that for
a period beginning on the date hereof and ending 12 months following the date of
the Participant’s termination of employment with the Companies for any reason,
the Participant shall not, on the Participant’s own behalf or on behalf of any
other person or entity, without the prior written consent of the Company,
directly or indirectly, solicit, hire or cause to be solicited or hired by an
enterprise with which Participant may ultimately become associated, or
participate in or promote the solicitation of, interfere with, attempt to
influence or otherwise affect the employment of, any employee of the Companies
whose annual compensation exceeds $100,000.

(c) Representation of Participant. Upon the acceptance by the Participant of the
Common Shares paid in respect of the Share Units, the Participant shall be
deemed to represent that the Participant has not engaged in nor has any
intention of engaging in any action that would constitute a violation of the
Restrictive Covenants or any Non-Compete Covenant.

(d) Injunctive Relief. The Participant acknowledges and agrees that the
Restrictive Covenant provisions of this Section 7 are reasonable and necessary
for the successful operation of the Companies. The Participant further
acknowledges that if the Participant breaches any provision of the Restrictive
Covenants, the Companies will suffer irreparable injury. It is therefore agreed
that the Company shall have the right to enjoin any such breach or threatened
breach, without posting any bond, if so ordered by a court of competent
jurisdiction. The existence of this right to injunctive and other equitable
relief shall not limit any other rights or remedies that the Company may have at
law or in equity including, without limitation, the right to monetary,
compensatory and punitive damages. In addition to any means at law or equity
available to the Company to enforce the Restrictive Covenants, the Company shall
retain any rights it may have under this Award Agreement for a breach of the
Restrictive Covenants including, without limitation, the right to cancel this
Share Unit Award and, in the event of a breach of Section 7(b) or any
Non-Compete Covenant, the right to require the Participant to return to the
Company any or all of the Common Shares (and cash reflecting dividend equivalent
rights) paid to the Participant in respect of the Share Units, in such manner
and on such terms and conditions as may be required by the Company. If any
provision of this Section 7 is determined by a court of competent jurisdiction
to be not enforceable in the manner set forth herein, the Participant and the
Company 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
provision of this Section 7 is held to be invalid or unenforceable, such
invalidity or unenforceability shall not affect the validity or enforceability
of any other provision of this Section 7.

Section 8. Changes in Capitalization. This Share Unit Award shall be subject to
the provisions of the Plan relating to adjustments for changes in corporate
capitalization.

Section 9. Notices. Any notice hereunder by the Participant shall be given to
the Company in writing and such notice shall be deemed duly given only upon
receipt thereof by the Secretary of the Company. Any notice hereunder by the
Company shall be given to the Participant in writing and such notice shall be
deemed duly given only upon receipt thereof at such address as the Participant
may have on file with the Company.

Section 10. Construction. This Award Agreement and the Share Unit Award
evidenced hereby are granted by the Company pursuant to the Plan and are in all
respects subject to the terms and conditions of the Plan. The Participant hereby
acknowledges that a copy of the Plan has been delivered to the Participant and
the Participant accepts the Share Units hereunder subject to all terms and
provisions of the Plan, which are incorporated herein by reference. In the event
of a conflict or ambiguity between any term or provision contained herein and a
term or provision of the Plan, then the Plan shall govern and prevail. The
construction of and decisions under the Plan and this Award Agreement are vested
in the Committee, whose determinations shall be final, conclusive and binding
upon the Participant.

Section 11. Governing Law. This Award Agreement and the Share Unit Award
evidenced hereby shall be governed by, and construed in accordance with, the
laws of the State of New York, excluding the choice of law rules thereof.

Section 12. Counterparts. This Award Agreement may be executed in counterparts,
each of which shall be deemed to be an original but all of which together shall
constitute one and the same instrument.

Section 13. Binding Effect. This Award Agreement shall be binding upon and inure
to the benefit of the legatees, distributees, and personal representatives of
the Participant and the successors of the Company.

Section 14. Entire Agreement. This Award Agreement and the Plan constitute the
entire agreement between the parties with respect to the subject matter hereof
and thereof, merging any and all prior agreements.

[SIGNATURES ON FOLLOWING PAGE]

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IN WITNESS WHEREOF, the Company and the Participant have executed this Award
Agreement effective as of the date first above written.

PLATINUM UNDERWRITERS HOLDINGS, LTD.

By:                                                             

Name:

Title:

PARTICIPANT

By:                                                              

Name:

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