Exhibit 4.16(a)

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                      COMMON SECURITIES GUARANTEE AGREEMENT

                                 XL CAPITAL LTD

                         Dated as of [        ], 20[  ]

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                                TABLE OF CONTENTS

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                                    ARTICLE I

                         DEFINITIONS AND INTERPRETATION

SECTION 1.1    Definitions Interpretation......................................1

                                   ARTICLE II

                                    GUARANTEE

SECTION 2.1    Guarantee.......................................................2
SECTION 2.2    Waiver of Notice and Demand.....................................3
SECTION 2.3    Obligations Not Affected........................................3
SECTION 2.4    Rights of Holders...............................................3
SECTION 2.5    Guarantee of Payment............................................3
SECTION 2.6    Subrogation.....................................................4
SECTION 2.7    Independent Obligations.........................................4

                                   ARTICLE III

                    LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 3.1    Limitation of Transactions......................................4
SECTION 3.2    Ranking.........................................................4

                                   ARTICLE IV

                                   TERMINATION

SECTION 4.1    Termination.....................................................5

                                    ARTICLE V

                                  MISCELLANEOUS

SECTION 5.1    Successors and Assigns..........................................5
SECTION 5.2    Amendments......................................................5
SECTION 5.3    Notices.........................................................5
SECTION 5.4    Benefit.........................................................6
SECTION 5.5    Governing Law...................................................6
SECTION 5.6    No Recourse Against Certain Persons.............................6


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                      COMMON SECURITIES GUARANTEE AGREEMENT

            GUARANTEE AGREEMENT (this "COMMON SECURITIES GUARANTEE"), dated as
of [       ], 20[  ], is executed and delivered by XL Capital Ltd, a Cayman
Islands exempted limited company (the "GUARANTOR"), for the benefit of the
Holders (as defined herein) from time to time of the Common Securities (as
defined herein) of XL Capital Trust [  ], a Delaware business trust (the
"ISSUER").

            WHEREAS, pursuant to an amended and restated Declaration of Trust
(the "DECLARATION"), dated as of [       ], 20[  ], among the Trustees of the
Issuer named therein, the Guarantor, as sponsor, and the holders from time to
time of undivided beneficial interests in the assets of the Issuer, the Issuer
is issuing on the date hereof [    ] common securities having an aggregate
liquidation amount of $[       ] designated the [    ]% Common Securities (the
"COMMON SECURITIES");

            WHEREAS, as incentive for the Holders to purchase the Common
Securities, the Guarantor desires to irrevocably and unconditionally agree, to
the extent set forth in this Common Securities Guarantee, to pay to the Holders
of the Common Securities the Guarantee Payments (as defined herein) and to make
certain other payments on the terms and conditions set forth herein; and

            WHEREAS, the Guarantor is also executing and delivering a guarantee
agreement (the "PREFERRED SECURITIES GUARANTEE") for the benefit of the holders
of the Preferred Securities (as defined herein), which terms include, among
other things, that if an Event of Default (as such term is defined in the
Indenture) has occurred and is continuing, the rights of Holders of the Common
Securities to receive Guarantee Payments under this Common Securities Guarantee
are subordinated to the rights of holders of Preferred Securities to receive
guarantee payments under the Preferred Securities Guarantee.

            NOW, THEREFORE, in consideration of the purchase by each Holder of
Common Securities, which purchase the Guarantor hereby agrees shall benefit the
Guarantor, the Guarantor executes and delivers this Common Securities Guarantee
for the benefit of the Holders.

                                    ARTICLE I

                         DEFINITIONS AND INTERPRETATION

SECTION 1.1 DEFINITIONS INTERPRETATION.

            In this Common Securities Guarantee, unless the context otherwise
requires:

            (a) capitalized terms used in this Common Securities Guarantee but
      not defined in the preamble above have the respective meanings assigned to
      them in this Section 1.1;

            (b) terms defined in the Declaration as at the date of execution of
      this Common Securities Guarantee have the same meaning when used in this
      Common Securities Guarantee unless otherwise defined in this Common
      Securities Guarantee;

            (c) a term defined anywhere in this Common Securities Guarantee has
      the same meaning throughout;

            (d) all references to "the Common Securities Guarantee" or "this
      Common Securities Guarantee" are to this Common Securities Guarantee as
      modified, supplemented or amended from time to time;

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            (e) all references in this Common Securities Guarantee to Articles
      and Sections are to Articles and Sections of this Common Securities
      Guarantee unless otherwise specified; and

            (f) a reference to the singular includes the plural and vice versa.

            "GUARANTEE PAYMENTS" shall mean the following payments or
distributions, without duplication, with respect to the Common Securities, to
the extent not paid or made by the Issuer: (i) any accrued and unpaid
Distributions that are required to be paid on such Common Securities, to the
extent the Issuer has funds available therefor, (ii) the redemption price,
including all accrued and unpaid Distributions to the date of redemption (the
"REDEMPTION PRICE"), to the extent the Issuer has funds available therefor, with
respect to any Common Securities called for redemption by the Issuer, and (iii)
upon a voluntary or involuntary dissolution, winding-up or termination of the
Issuer (other than in connection with the distribution of Subordinated Notes to
the Holders in exchange for Common Securities as provided in the Declaration),
the lesser of (a) the aggregate of the liquidation amount and all accrued and
unpaid Distributions on the Common Securities to the date of payment, to the
extent the Issuer has funds available therefor, and (b) the amount of assets of
the Issuer remaining available for distribution to Holders in liquidation of the
Issuer (in either case, the "LIQUIDATION Distribution"). If an Event of Default
(as defined in the Indenture) has occurred and is continuing, the rights of
Holders of the Common Securities to receive Guarantee Payments under this Common
Securities Guarantee are subordinated to the rights of holders of Preferred
Securities to receive guarantee payments under the Preferred Securities
Guarantee.

            "HOLDER" shall mean any holder, as registered on the books and
records of the Issuer, of any Common Securities.

            "INDENTURE" means the Indenture dated as of June 2, 2004, between
the Guarantor and The Bank of New York, as Trustee, and the First Supplemental
Indenture thereto pursuant to which certain subordinated debt securities of the
Guarantor are to be issued to the Property Trustee (as defined in the
Declaration), as from time to time amended.

            "PROPERTY TRUSTEE" shall have the meaning ascribed to such term in
the Declaration.

            "SUBORDINATED NOTES" means the series of subordinated debt
securities of the Guarantor designated the [ ]% Subordinated Deferrable Interest
Notes due [       ], 20[  ] held by the Property Trustee.

            "PREFERRED SECURITIES" shall mean the securities representing
preferred undivided beneficial interests in the assets of the Issuer.

            "XL" shall mean XL Capital Ltd, a Cayman Islands exempted limited
company.

                                   ARTICLE II

                                    GUARANTEE

SECTION 2.1 GUARANTEE

            The Guarantor irrevocably and unconditionally agrees to pay in full
to the Holders the Guarantee Payments (without duplication of amounts
theretofore paid by the Issuer), as and when due, regardless of any defense,
right of set-off or counterclaim which the Issuer may have or assert. The
Guarantor's obligation to make a Guarantee Payment may be satisfied by direct
payment of the required amounts by the Guarantor to the Holders or by causing
the Issuer to pay such amounts to the Holders.


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SECTION 2.2 WAIVER OF NOTICE AND DEMAND

            The Guarantor hereby waives notice of acceptance of this Common
Securities Guarantee and of any liability to which it applies or may apply,
presentment, demand for payment, any right to require a proceeding first against
the Issuer or any other Person before proceeding against the Guarantor, protest,
notice of nonpayment, notice of dishonor, notice of redemption and all other
notices and demands.

SECTION 2.3 OBLIGATIONS NOT AFFECTED

            The obligations, covenants, agreements and duties of the Guarantor
under this Common Securities Guarantee shall in no way be affected or impaired
by reason of the happening from time to time of any of the following:

            (a) the release or waiver, by operation of law or otherwise, of the
      performance or observance by the Issuer of any express or implied
      agreement, covenant, term or condition relating to the Common Securities
      to be performed or observed by the Issuer;

            (b) the extension of time for the payment by the Issuer of all or
      any portion of the Distributions, Redemption Price, Liquidation
      Distribution or any other sums payable under the terms of the Common
      Securities or the extension of time for the performance of any other
      obligation under, arising out of, or in connection with, the Common
      Securities (other than an extension of time for payment of Distributions
      or other sum payable that results from the extension of any interest
      payment period on the Subordinated Notes permitted by the Indenture);

            (c) any failure, omission, delay or lack of diligence on the part of
      the Holders to enforce, assert or exercise any right, privilege, power or
      remedy conferred on the Holders pursuant to the terms of the Common
      Securities, or any action on the part of the Issuer granting indulgence or
      extension of any kind;

            (d) the voluntary or involuntary liquidation, dissolution, sale of
      any collateral, receivership, insolvency, bankruptcy, assignment for the
      benefit of creditors, reorganization, arrangement, composition or
      readjustment of debt of, or other similar proceedings affecting, the
      Issuer or any of the assets of the Issuer;

            (e) any invalidity of, or defect or deficiency in, the Common
      Securities;

            (f) the settlement or compromise of any obligation guaranteed hereby
      or hereby incurred; or

            (g) any other circumstance whatsoever that might otherwise
      constitute a legal or equitable discharge or defense of a guarantor;

it being the intent of this Section 2.3 that the obligations of the Guarantor
hereunder shall be absolute and unconditional under any and all circumstances.

            There shall be no obligation of the Holders to give notice to, or
obtain consent of, the Guarantor with respect to the happening of any of the
foregoing.

SECTION 2.4 RIGHTS OF HOLDERS

            The Guarantor expressly acknowledges that any Holder of Common
Securities may institute a legal proceeding directly against the Guarantor to
enforce its rights under this Common Securities Guarantee, without first
instituting a legal proceeding against the Issuer or any other Person.

SECTION 2.5 GUARANTEE OF PAYMENT

            This Common Securities Guarantee creates a guarantee of payment and
not of collection.


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SECTION 2.6 SUBROGATION

            The Guarantor shall be subrogated to all (if any) rights of the
Holders of Common Securities against the Issuer in respect of any amounts paid
to such Holders by the Guarantor under this Common Securities Guarantee;
PROVIDED, HOWEVER, that the Guarantor shall not (except to the extent required
by mandatory provisions of law) be entitled to enforce or exercise any rights
which it may acquire by way of subrogation or any indemnity, reimbursement or
other agreement, in all cases as a result of payment under this Common
Securities Guarantee, if, at the time of any such payment, any amounts are due
and unpaid under this Common Securities Guarantee. If any amount shall be paid
to the Guarantor in violation of the preceding sentence, the Guarantor agrees to
hold such amount in trust for the Holders and to pay over such amount to the
Holders.

SECTION 2.7 INDEPENDENT OBLIGATIONS

            The Guarantor acknowledges that its obligations hereunder are
independent of the obligations of the Issuer with respect to the Common
Securities and that the Guarantor shall be liable as principal and as debtor
hereunder to make Guarantee Payments pursuant to the terms of this Common
Securities Guarantee notwithstanding the occurrence of any event referred to in
subsections (a) through (g), inclusive, of Section 2.3 hereof.

                                   ARTICLE III

                    LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 3.1 LIMITATION OF TRANSACTIONS

            (a) So long as any Common Securities remain outstanding, if (i) the
Guarantor shall be in default with respect to its Guarantee Payments or other
obligations hereunder, or (ii) if an Event of Default (as defined in the
Indenture) shall exist then (a) the Guarantor shall not declare or pay any
dividend on, or make any distributions with respect to, or redeem, purchase,
acquire or make a liquidation payment with respect to, any of its capital stock
and (b) the Guarantor shall not make any payment of interest, principal or
premium, if any, on or repay, repurchase or redeem any debt securities issued by
the Guarantor which rank PARI PASSU with or junior to the Subordinated Notes.

            (b) Notwithstanding subsection 3.1(a) or any other language to the
contrary contained in this Common Securities Guarantee, nothing shall prevent
the Guarantor from: (i) declaring or paying any dividend on, or making any
distribution with respect to, or redeeming, purchasing, acquiring or making a
liquidation payment with respect to, any of its capital stock in or with (x)
securities of the Guarantor (including capital stock) that rank junior to such
capital stock or (y) securities (including capital stock) of XL or (ii) paying
any interest, principal or premium on, or repaying, repurchasing or redeeming,
any debt securities issued by the Guarantor which rank PARI PASSU with or junior
to the Subordinated Notes, with (x) securities of the Guarantor (including
capital stock) that rank junior to such debt securities or (y) securities
(including capital stock) of XL.

SECTION 3.2 RANKING

            This Common Securities Guarantee will constitute an unsecured
obligation of the Guarantor and will rank (i) subordinate and junior in right of
payment to all other liabilities of the Guarantor, including the Subordinated
Notes and the Preferred Securities Guarantee, except those liabilities of the
Guarantor made PARI PASSU or subordinate by their terms, (ii) PARI PASSU with
the most senior preferred stock issued from time to time by the Guarantor and
with any guarantee now or hereafter entered into by the Guarantor in respect of
any preferred stock of any Subsidiary or Affiliate of the Guarantor, except the
Preferred Securities Guarantee, and (iii) senior to the Guarantor's common
stock.


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                                   ARTICLE IV

                                   TERMINATION

SECTION 4.1 TERMINATION

            This Common Securities Guarantee shall terminate upon the first to
occur of (i) full payment of the Redemption Price of all Common Securities, (ii)
the distribution of Subordinated Notes to the Holders of all of the Common
Securities or (iii) the full payment of the amounts payable in accordance with
the Declaration upon liquidation of the Issuer. Notwithstanding the foregoing,
this Common Securities Guarantee will continue to be effective or will be
reinstated, as the case may be, if at any time any Holder of Common Securities
must restore payment of any sums paid under the Common Securities or under this
Common Securities Guarantee.

                                    ARTICLE V

                                  MISCELLANEOUS

SECTION 5.1 SUCCESSORS AND ASSIGNS

            All guarantees and agreements contained in this Common Securities
Guarantee shall bind the successors, assigns, receivers, trustees and
representatives of the Guarantor and shall inure to the benefit of the Holders
of the Common Securities then outstanding.

SECTION 5.2 AMENDMENTS

            Except with respect to any changes which do not adversely affect the
rights of Holders (in which case no consent of Holders will be required), this
Common Securities Guarantee may only be amended with the prior approval of the
Holders of at least a majority in liquidation amount of all the outstanding
Common Securities. The provisions of Section 12.2 of the Declaration with
respect to meetings of Holders of the Securities apply to the giving of such
approval.

SECTION 5.3 NOTICES

            All notices provided for in this Common Securities Guarantee shall
be in writing, duly signed by the party giving such notice, and shall be
delivered, telecopied or mailed by registered or certified mail, as follows:

            (a) if given to the Issuer, in care of the Regular Trustees at the
      Issuer's mailing address set forth below (or such other address as the
      Issuer may give notice of to the Holders of the Common Securities):

                   XL Capital Trust I
                   c/o XL Capital Ltd
                   XL House
                   One Bermudiana Road
                   Hamilton HM11
                   Bermuda
                   Attention: Paul S. Giordano

            (b) if given to the Guarantor, at the Guarantor's mailing address
      set forth below (or such other address as the Guarantor may give notice of
      to the Holders of the Common Securities):


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                   XL Capital Ltd
                   XL House
                   One Bermudiana Road
                   Hamilton HM11
                   Bermuda
                   Attention: Paul S. Giordano

            (c) if given to any Holder of Common Securities, at the address set
      forth on the books and records of the Issuer.

            All such notices shall be deemed to have been given when received in
person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid except that if a notice or other document is refused delivery or
cannot be delivered because of a changed address of which no notice was given,
such notice or other document shall be deemed to have been delivered on the date
of such refusal or inability to deliver.

SECTION 5.4 BENEFIT

            This Common Securities Guarantee is solely for the benefit of the
Holders of the Common Securities and is not separately transferable from the
Common Securities.

SECTION 5.5 GOVERNING LAW

            THIS COMMON SECURITIES GUARANTEE SHALL BE GOVERNED BY, AND CONSTRUED
AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

SECTION 5.6 NO RECOURSE AGAINST CERTAIN PERSONS

            No past, present or future director, officer, employee or
stockholder, as such, of the Guarantor or any successor thereof shall have any
liability for any obligations of the Guarantor under this Preferred Securities
Guarantee or for any claim based on, in respect of, or by reason of, such
obligations or their creation and all such liability is hereby waived and
released. Such waiver and release are part of the consideration for the issue of
this Common Securities Guarantee and the Common Securities.


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            IN WITNESS WHEREOF, XL CAPITAL LTD has caused this Common Securities
Guarantee Agreement to be duly executed as a deed the day and year first before
written.


By: ______________________________
    Name:
    Title:


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