<PAGE>   1

                                                                 EXHIBIT 4.11(a)

                               GUARANTEE AGREEMENT

                                 BY AND BETWEEN

                              INDYMAC BANCORP, INC.

                                  AS GUARANTOR

                                       AND

                   THE BANK OF NEW YORK, AS GUARANTEE TRUSTEE

                                   RELATING TO

                             INDYMAC CAPITAL TRUST I

                           ---------------------------

                         DATED AS OF _____________, 2001

                           ---------------------------


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                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                   PAGE
                                                                                                   ----
<S>                                                                                                <C>
ARTICLE I DEFINITIONS............................................................................    1

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

ARTICLE II TRUST INDENTURE ACT...................................................................    4

    SECTION 2.1.    Trust Indenture Act; Application.............................................    4

    SECTION 2.2.    List of Holder...............................................................    5

    SECTION 2.3.    Reports by the Guarantee Trustee.............................................    5

    SECTION 2.4.    Periodic Reports to the Guarantee Trustee....................................    5

    SECTION 2.4.    Evidence of Compliance with Conditions Precedent.............................    5

    SECTION 2.6.    Events of Default; Waiver....................................................    6

    SECTION 2.7.    Event of Default; Notice.....................................................    6

    SECTION 2.8.    Conflicting Interests........................................................    6

ARTICLE III POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE...................................    6

    SECTION 3.1.    Powers and Duties of the Guarantee Trustee...................................    6

    SECTION 3.2.    Certain Rights of Guarantee Trustee..........................................    8

    SECTION 3.3.    Compensation; Indemnity; Fees................................................    9

ARTICLE IV GUARANTEE TRUSTEE.....................................................................   10

    SECTION 4.1.    Guarantee Trustee; Eligibility...............................................   10

    SECTION 4.2.    Appointment, Removal and Resignation of the Guarantee Trustee................   10

ARTICLE V GUARANTEE..............................................................................   11

    SECTION 5.1.    Guarantee....................................................................   11

    SECTION 5.2.    Waiver of Notice and Demand..................................................   11

    SECTION 5.3.    Obligations Not Affected.....................................................   12

    SECTION 5.4.    Rights of Holders............................................................   12

    SECTION 5.5.    Guarantee of Payment.........................................................   13

    SECTION 5.6.    Subrogation..................................................................   13

    SECTION 5.7.    Independent Obligations......................................................   13
</TABLE>


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<TABLE>
<S>                                                                                                <C>
ARTICLE VI COVENANTS AND SUBORDINATION...........................................................   13

    SECTION 6.1.    Subordination................................................................   13

    SECTION 6.2.    Pari Passu Guarantees........................................................   14

ARTICLE VII TERMINATION..........................................................................   14

    SECTION 7.1.    Termination..................................................................   14

ARTICLE VIII MISCELLANEOUS.......................................................................   14

    SECTION 8.1.    Successors and Assigns.......................................................   14

    SECTION 8.2.    Amendments...................................................................   14

    SECTION 8.3.    Notices......................................................................   15

    SECTION 8.4.    Benefit......................................................................   15

    SECTION 8.5.    Governing Law................................................................   16

    SECTION 8.6.    Counterparts.................................................................   16
</TABLE>


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       GUARANTEE AGREEMENT, dated as of _____________, 2001, between INDYMAC
BANCORP, INC., a Delaware corporation (the "Guarantor"), having its principal
office at 155 North Lake Avenue, Pasadena, California 91101, and THE BANK
OF NEW YORK, as trustee (the "Guarantee Trustee"), for the benefit of the
Holders (as defined herein) from time to time of the Trust Preferred Securities
(as defined herein) of INDYMAC CAPITAL TRUST I, a Delaware statutory business
trust (the "Issuer Trust").

                                    RECITALS

       WHEREAS, pursuant to an Amended and Restated Declaration of Trust and
Trust Agreement, of even date herewith (the "Trust Agreement"), among IndyMac
Bancorp, Inc., as Depositor, the Property Trustee, the Delaware Trustee, and the
Administrative Trustees (each as named therein) and the holders from time to
time of undivided beneficial interests in the assets of the Issuer Trust, the
Issuer Trust is issuing $[_____________] aggregate Liquidation Amount (as
defined in the Trust Agreement) of its [**[__%]Preferred Securities (liquidation
amount $1,000 per Trust Preferred Security)] (the "Trust Preferred Securities"),
representing preferred undivided beneficial interests in the assets of the
Issuer Trust and having the terms set forth in the Trust Agreement; and

       WHEREAS, the Trust Preferred Securities will be issued by the Issuer
Trust, and the proceeds thereof, together with the proceeds from the issuance of
the Issuer Trust's Common Securities (as defined herein), will be used to
purchase the Debentures of the Guarantor, which Debentures will be deposited
with The Bank of New York, as Property Trustee under the Trust Agreement, as
trust assets; and

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

       NOW, THEREFORE, in consideration of the purchase of Trust Preferred
Securities by each Holder, which purchase the Guarantor hereby acknowledges
shall benefit the Guarantor, the Guarantor executes and delivers this Guarantee
Agreement for the benefit of the Holders from time to time.

                                    ARTICLE I
                                   DEFINITIONS

       SECTION 1.1. DEFINITIONS.

       For all purposes of this Guarantee Agreement, except as otherwise
expressly provided or unless the context otherwise requires:

       (a) The terms defined in this Article have the meanings assigned to them
in this Article, and include the plural as well as the singular;


<PAGE>   5

       (b) All other terms used herein that are defined in the Trust Indenture
Act, either directly or by reference therein, have the meanings assigned to them
therein;

       (c) The words "include," "includes" and "including" shall be deemed to be
followed by the phrase "without limitation";

       (d) All accounting terms used but not defined herein have the meanings
assigned to them in accordance with United States generally accepted accounting
principles;

       (e) Unless the context otherwise requires, any reference to an "Article"
or a "Section" refers to an Article or a Section, as the case may be, of this
Guarantee Agreement; and

       (f) The words "hereby," "herein," "hereof" and "hereunder" and other
words of similar import refer to this Guarantee Agreement as a whole and not to
any particular Article, Section or other subdivision.

       "Affiliate" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For the purposes of this definition,
"control," when used with respect to any specified Person, means the power to
direct the management and policies of such Person, directly or indirectly,
whether through the ownership of voting securities, by contract or otherwise;
and the terms "controlling" and "controlled" have meanings correlative to the
foregoing.

       "Board of Directors" means the board of directors of the Guarantor or any
committee of the board of directors of the Guarantor, comprised of one or more
members of the board of directors of the Guarantor or officers of the Guarantor,
or both.

       "Trust Preferred Securities" has the meaning specified in the recitals to
this Guarantee Agreement.

       "Common Securities" means the securities representing common undivided
beneficial interests in the assets of the Issuer Trust.

       "Debentures" shall have the meaning specified in the Trust Agreement.

       "Distributions" shall have the meaning specified in the Trust Agreement.

       "Event of Default" means (i) a default by the Guarantor in any of its
payment obligations under this Guarantee Agreement or (ii) a default by the
Guarantor in any other obligation hereunder that remains unremedied for 30 days.

       "Guarantee Agreement" means this Guarantee Agreement, as modified,
amended or supplemented from time to time.

       "Guarantee Payments" means the following payments or distributions,
without duplication, with respect to the Trust Preferred Securities, to the
extent not paid or made by or on behalf of the Issuer Trust: (i) any accumulated
and unpaid Distributions required to be paid on the Trust Preferred Securities,
to the extent the Issuer Trust shall have funds on hand available


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therefor at such time; (ii) the Redemption Price with respect to any Trust
Preferred Securities called for redemption by the Issuer Trust, to the extent
the Issuer Trust shall have funds on hand available therefor at such time; and
(iii) upon a voluntary or involuntary dissolution, winding-up or liquidation of
the Issuer Trust, unless Debentures are distributed to the Holders, the lesser
of (a) the Liquidation Distribution with respect to the Trust Preferred
Securities, to the extent that the Issuer Trust shall have funds on hand
available therefor at such time, and (b) the amount of assets of the Issuer
Trust remaining available for distribution to Holders on liquidation of the
Issuer.

       "Guarantee Trustee" means The Bank of New York, solely in its capacity as
Guarantee Trustee and not in its individual capacity, until a Successor
Guarantee Trustee has been appointed and has accepted such appointment pursuant
to the terms of this Guarantee Agreement, and thereafter means each such
Successor Guarantee Trustee.

       "Guarantor" has the meaning specified in the first paragraph of this
Guarantee Agreement.

       "Holder" means any Holder (as defined in the Trust Agreement) of any
Trust Preferred Securities; provided, however, that in determining whether the
holders of the requisite percentage of Trust Preferred Securities have given any
request, notice, consent or waiver hereunder, "Holder" shall not include the
Guarantor, the Guarantee Trustee, or any Affiliate of the Guarantor or the
Guarantee Trustee.

       "Indenture" means the Junior Subordinated Indenture, dated as of
______________ 2001, between IndyMac Bancorp, Inc. and The Bank of New York, as
trustee, as the same may be modified, amended or supplemented from time to time.

       "Issuer Trust" has the meaning specified in the first paragraph of this
Guarantee Agreement.

       "Liquidation Distribution" shall have the meaning specified in the Trust
Agreement.

       "List of Holders" has the meaning specified in Section 2.2(a).

       "Majority in Liquidation Amount of the Trust Preferred Securities" means,
except as provided by the Trust Indenture Act, Trust Preferred Securities
representing more than 50% of the aggregate Liquidation Amount (as defined in
the Trust Agreement) of all Trust Preferred Securities then Outstanding (as
defined in the Trust Agreement).

       "Officers' Certificate" means, with respect to any Person, a certificate
signed by the Chairman or a Vice Chairman of the Board of Directors of such
Person or the President or a Vice President of such Person, and by the
Treasurer, an Assistant Treasurer, the Secretary or an Assistant Secretary of
such Person. Any Officers' Certificate delivered with respect to compliance with
a condition or covenant provided for in this Guarantee Agreement shall include:

       (a) a statement by each officer signing the Officers' Certificate that
such officer has read the covenant or condition and the definitions relating
thereto;


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       (b) a brief statement of the nature and scope of the examination or
investigation undertaken by such officer in rendering the Officers' Certificate;

       (c) a statement that such officer has made such examination or
investigation as, in such officer's opinion, is necessary to enable such officer
to express an informed opinion as to whether or not such covenant or condition
has been complied with; and

       (d) a statement as to whether, in the opinion of such officer, such
condition or covenant has been complied with.

       "Person" means a legal person, including any individual, corporation,
estate, partnership, joint venture, association, joint stock company, company,
limited liability company, trust, business trust, unincorporated association, or
government or any agency or political subdivision thereof, or any other entity
of whatever nature.

       "Redemption Price" shall have the meaning set forth in the Trust
Agreement.

       "Responsible Officer" means, with respect to the Guarantee Trustee, any
Senior Vice President, any Vice President, any Assistant Vice President, the
Secretary, any Assistant Secretary, the Treasurer, any Assistant Treasurer, any
Trust Officer or Assistant Trust Officer or any other officer of the Corporate
Trust Department of the Guarantee Trustee and also means, with respect to a
particular matter, any other officer to whom such matter is referred because of
that officer's knowledge of and familiarity with the particular subject.

       "Successor Guarantee Trustee" means a successor Guarantee Trustee
possessing the qualifications to act as Guarantee Trustee under Section 4.1.

       "Trust Agreement" means the Amended and Restated Declaration of Trust and
Trust Agreement of the Issuer Trust referred to in the recitals to this
Guarantee Agreement, as modified, amended or supplemented from time to time.

       "Trust Indenture Act" means the Trust Indenture Act of 1939 as in force
at the date as of which this Guarantee Agreement was executed; provided,
however, that in the event the Trust Indenture Act of 1939 is amended after such
date, "Trust Indenture Act" means, to the extent required by any such amendment,
the Trust Indenture Act of 1939 as so amended.

       "Vice President," when used with respect to the Guarantor, means any duly
appointed vice president, whether or not designated by a number or a word or
words added before or after the title "vice president."

                                   ARTICLE II
                               TRUST INDENTURE ACT

       SECTION 2.1. TRUST INDENTURE ACT; APPLICATION.

       Except as otherwise expressly provided herein, the Trust Indenture Act
shall apply as a matter of contract to this Guarantee Agreement for purposes of
interpretation, construction and defining the rights and obligations hereunder,
and this Guarantee Agreement, the Guarantor and


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the Guarantee Trustee shall be deemed for all purposes hereof to be subject to
and governed by the Trust Indenture Act to the same extent as would be the case
if this Guarantee Agreement were qualified under the Trust Indenture Act on the
date hereof. Except as otherwise expressly provided herein, if and to the extent
that any provision of this Guarantee Agreement limits, qualifies or conflicts
with the duties imposed by Sections 310 to 317, inclusive, of the Trust
Indenture Act, such imposed duties shall control.

       SECTION 2.2. LIST OF HOLDERS.

       (a) The Guarantor shall furnish or cause to be furnished to the Guarantee
Trustee (a) semiannually, on or before June 30 and December 31 of each year, a
list, in such form as the Guarantee Trustee may reasonably require, of the names
and addresses of the Holders (a "List of Holders") as of a date not more than 15
days prior to the delivery thereof, and (b) at such other times as the Guarantee
Trustee may request in writing, within 30 days after the receipt by the
Guarantor of any such request, a List of Holders as of a date not more than 15
days prior to the time such list is furnished, in each case to the extent such
information is in the possession or control of the Guarantor and has not
otherwise been received by the Guarantee Trustee in its capacity as such. The
Guarantee Trustee may destroy any List of Holders previously given to it on
receipt of a new List of Holders.

       (b) The Guarantee Trustee shall comply with the requirements of Section
311(a), Section 311(b) and Section 312(b) of the Trust Indenture Act.

       SECTION 2.3. REPORTS BY THE GUARANTEE TRUSTEE.

       Within 60 days after [date] each year, commencing [date], the Guarantee
Trustee shall provide to the Holders such reports as are required by Section 313
of the Trust Indenture Act, if any, in the form and in the manner provided by
Section 313 of the Trust Indenture Act. If this Guarantee Agreement shall have
been qualified under the Trust Indenture Act, the Guarantee Trustee shall also
comply with the requirements of Section 313(d) of the Trust Indenture Act.

       SECTION 2.4. PERIODIC REPORTS TO THE GUARANTEE TRUSTEE.

       The Guarantor shall provide to the Guarantee Trustee and the Holders such
documents, reports and information, if any, as required by Section 314 of the
Trust Indenture Act and the compliance certificate required by Section 314 of
the Trust Indenture Act, in the form, in the manner and at the times required by
Section 314 of the Trust Indenture Act, provided that such documents, reports
and information shall be required to be provided to the Securities and Exchange
Commission only if this Guarantee Agreement shall have been qualified under the
Trust Indenture Act.

       SECTION 2.5. EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT.

       The Guarantor shall provide to the Guarantee Trustee such evidence of
compliance with such conditions precedent, if any, provided for in this
Guarantee Agreement that relate to any of the matters set forth in Section
314(c) of the Trust Indenture Act. Any certificate or opinion required to be
given by an officer of the Guarantor pursuant to Section 314(c)(1) may be given
in the form of an Officers' Certificate.


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       SECTION 2.6. EVENTS OF DEFAULT; WAIVER.

       The Holders of at least a Majority in Liquidation Amount of the Trust
Preferred Securities may, by vote, on behalf of the Holders of all the Trust
Preferred Securities, waive any past default or Event of Default and its
consequences. Upon such waiver, any such default or Event of Default shall cease
to exist, and any default or Event of Default arising therefrom shall be deemed
to have been cured, for every purpose of this Guarantee Agreement, but no such
waiver shall extend to any subsequent or other default or Event of Default or
impair any right consequent thereon.

       SECTION 2.7. EVENT OF DEFAULT; NOTICE.

       (a) The Guarantee Trustee shall, within 10 days after the occurrence of
an Event of Default known to the Guarantee Trustee, transmit by mail, first
class postage prepaid, to the Holders, notice of any such Event of Default known
to the Guarantee Trustee, unless such Event of Default has been cured before the
giving of such notice, provided that, except in the case of a default in the
payment of a Guarantee Payment, the Guarantee Trustee shall be protected in
withholding such notice if and so long as the board of directors, the executive
committee or a trust committee of directors and/or Responsible Officers of the
Guarantee Trustee in good faith determines that the withholding of such notice
is in the interests of the Holders.

       (b) The Guarantee Trustee shall not be deemed to have knowledge of any
Event of Default unless the Guarantee Trustee shall have received written
notice, or a Responsible Officer charged with the administration of this
Guarantee Agreement shall have obtained written notice, of such Event of
Default.

       SECTION 2.8. CONFLICTING INTERESTS.

       The Trust Agreement and the Indenture shall be deemed to be specifically
described in this Guarantee Agreement for the purposes of clause (i) of the
first proviso contained in Section 310(b) of the Trust Indenture Act.

                                   ARTICLE III
               POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE

       SECTION 3.1. POWERS AND DUTIES OF THE GUARANTEE TRUSTEE.

       (a) This Guarantee Agreement shall be held by the Guarantee Trustee for
the benefit of the Holders, and the Guarantee Trustee shall not transfer this
Guarantee Agreement to any Person except to a Successor Guarantee Trustee on
acceptance by such Successor Guarantee Trustee of its appointment to act as
Guarantee Trustee hereunder. The right, title and interest of the Guarantee
Trustee, as such, hereunder shall automatically vest in any Successor Guarantee
Trustee, upon acceptance by such Successor Guarantee Trustee of its appointment
hereunder, and such vesting and cessation of title shall be effective whether or
not conveyancing documents have been executed and delivered pursuant to the
appointment of such Successor Guarantee Trustee.


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       (b) If an Event of Default has occurred and is continuing, the Guarantee
Trustee shall enforce this Guarantee Agreement for the benefit of the Holders.

       (c) The Guarantee Trustee, before the occurrence of any Event of Default
and after the curing of all Events of Default that may have occurred, shall
undertake to perform only such duties as are specifically set forth in this
Guarantee Agreement (including pursuant to Section 2.1), and no implied
covenants shall be read into this Guarantee Agreement against the Guarantee
Trustee. If an Event of Default has occurred (that has not been cured or waived
pursuant to Section 2.6), the Guarantee Trustee shall exercise such of the
rights and powers vested in it by this Guarantee Agreement, and use the same
degree of care and skill in its exercise thereof, as a prudent person would
exercise or use under the circumstances in the conduct of his or her own
affairs.

       (d) No provision of this Guarantee Agreement shall be construed to
relieve the Guarantee Trustee from liability for its own negligent action, its
own negligent failure to act or its own willful misconduct, except that:

              (i) prior to the occurrence of any Event of Default and after the
       curing or waiving of all such Events of Default that may have occurred:

                     (A) the duties and obligations of the Guarantee Trustee
              shall be determined solely by the express provisions of this
              Guarantee Agreement (including pursuant to Section 2.1), and the
              Guarantee Trustee shall not be liable except for the performance
              of such duties and obligations as are specifically set forth in
              this Guarantee Agreement (including pursuant to Section 2.1); and

                     (B) in the absence of bad faith on the part of the
              Guarantee Trustee, the Guarantee Trustee may conclusively rely, as
              to the truth of the statements and the correctness of the opinions
              expressed therein, upon any certificates or opinions furnished to
              the Guarantee Trustee and conforming to the requirements of this
              Guarantee Agreement (but in the case of any such certificates or
              opinions that by any provision hereof or of the Trust Indenture
              Act are specifically required to be furnished to the Guarantee
              Trustee, the Guarantee Trustee shall be under a duty to examine
              the same to determine whether or not they conform to the
              requirements of this Guarantee Agreement);

              (ii) the Guarantee Trustee shall not be liable for any error of
       judgment made in good faith by a Responsible Officer of the Guarantee
       Trustee, unless it shall be proved that the Guarantee Trustee was
       negligent in ascertaining the pertinent facts upon which such judgment
       was made;

              (iii) the Guarantee Trustee shall not be liable with respect to
       any action taken or omitted to be taken by it in good faith in accordance
       with the direction of the Holders of not less than a Majority in
       Liquidation Amount of the Trust Preferred Securities relating to the
       time, method and place of conducting any proceeding for any remedy
       available to the Guarantee Trustee, or exercising any trust or power
       conferred upon the Guarantee Trustee under this Guarantee Agreement; and


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<PAGE>   11

              (iv) subject to Section 3.1(b), no provision of this Guarantee
       Agreement shall require the Guarantee Trustee to expend or risk its own
       funds or otherwise incur personal financial liability in the performance
       of any of its duties or in the exercise of any of its rights or powers,
       if the Guarantee Trustee shall have reasonable grounds for believing that
       the repayment of such funds or liability is not reasonably assured to it
       under the terms of this Guarantee Agreement or adequate indemnity against
       such risk or liability is not reasonably assured to it.

       SECTION 3.2. CERTAIN RIGHTS OF GUARANTEE TRUSTEE.

       (a) Subject to the provisions of Section 3.1:

              (i) The Guarantee Trustee may rely and shall be fully protected in
       acting or refraining from acting upon any resolution, certificate,
       statement, instrument, opinion, report, notice, request, direction,
       consent, order, bond, debenture, note, other evidence of indebtedness or
       other paper or document reasonably believed by it to be genuine and to
       have been signed, sent or presented by the proper party or parties.

              (ii) Any direction or act of the Guarantor contemplated by this
       Guarantee Agreement shall be sufficiently evidenced by an Officers'
       Certificate unless otherwise prescribed herein.

              (iii) Whenever, in the administration of this Guarantee Agreement,
       the Guarantee Trustee shall deem it desirable that a matter be proved or
       established before taking, suffering or omitting to take any action
       hereunder, the Guarantee Trustee (unless other evidence is herein
       specifically prescribed) may, in the absence of bad faith on its part,
       request and rely upon an Officers' Certificate which, upon receipt of
       such request from the Guarantee Trustee, shall be promptly delivered by
       the Guarantor.

              (iv) The Guarantee Trustee may consult with legal counsel, and the
       written advice or opinion of such legal counsel with respect to legal
       matters shall be full and complete authorization and protection in
       respect of any action taken, suffered or omitted to be taken by it
       hereunder in good faith and in accordance with such advice or opinion.
       Such legal counsel may be legal counsel to the Guarantor or any of its
       Affiliates and may be one of its employees. The Guarantee Trustee shall
       have the right at any time to seek instructions concerning the
       administration of this Guarantee Agreement from any court of competent
       jurisdiction.

              (v) The Guarantee Trustee shall be under no obligation to exercise
       any of the rights or powers vested in it by this Guarantee Agreement at
       the request or direction of any Holder unless such Holder shall have
       provided to the Guarantee Trustee such adequate security and indemnity as
       would satisfy a reasonable person in the position of the Guarantee
       Trustee against the costs, expenses (including attorneys' fees and
       expenses) and liabilities that might be incurred by it in complying with
       such request or direction, including such reasonable advances as may be
       requested by the Guarantee Trustee; provided that nothing contained in
       this Section (a)(v) shall be taken to relieve the


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<PAGE>   12

       Guarantee Trustee, upon the occurrence of an Event of Default, of its
       obligation to exercise the rights and powers vested in it by this
       Guarantee Agreement.

              (vi) The Guarantee Trustee shall not be bound to make any
       investigation into the facts or matters stated in any resolution,
       certificate, statement, instrument, opinion, report, notice, request,
       direction, consent, order, bond, debenture, note, other evidence of
       indebtedness or other paper or document, but the Guarantee Trustee, in
       its discretion, may make such further inquiry or investigation into such
       facts or matters as it may see fit.

              (vii) The Guarantee Trustee may execute any of the trusts or
       powers hereunder or perform any duties hereunder either directly or by or
       through its agents or attorneys, and the Guarantee Trustee shall not be
       responsible for any misconduct or negligence on the part of any such
       agent or attorney appointed by it with due care hereunder.

              (viii) Whenever in the administration of this Guarantee Agreement
       the Guarantee Trustee shall deem it desirable to receive instructions
       with respect to enforcing any remedy or right or taking any other action
       hereunder, the Guarantee Trustee (A) may request instructions from the
       Holders, (B) may refrain from enforcing such remedy or right or taking
       such other action until such instructions are received, and (C) shall be
       protected in acting in accordance with such instructions.

       (b) No provision of this Guarantee Agreement shall be deemed to impose
any duty or obligation on the Guarantee Trustee to perform any act or acts or
exercise any right, power, duty or obligation conferred or imposed on it in any
jurisdiction in which it shall be illegal, or in which the Guarantee Trustee
shall be unqualified or incompetent in accordance with applicable law, to
perform any such act or acts or to exercise any such right, power, duty or
obligation. No permissive power or authority available to the Guarantee Trustee
shall be construed to be a duty to act in accordance with such power and
authority.

       SECTION 3.3. COMPENSATION; INDEMNITY; FEES.

       The Guarantor agrees:

       (a) to pay to the Guarantee Trustee from time to time such reasonable
compensation for all services rendered by it hereunder as may be agreed by the
Guarantor and the Guarantee Trustee from time to time (which compensation shall
not be limited by any provision of law in regard to the compensation of a
trustee of an express trust);

       (b) except as otherwise expressly provided herein, to reimburse the
Guarantee Trustee upon request for all reasonable expenses, disbursements and
advances incurred or made by the Guarantee Trustee in accordance with any
provision of this Guarantee Agreement (including the reasonable compensation and
the expenses and disbursements of its agents and counsel), except any such
expense, disbursement or advance as may be attributable to its negligence or bad
faith; and

       (c) to indemnify the Guarantee Trustee, any Affiliate of the Guarantee
Trustee and any officer, director, shareholder, employee, representative or
agent of the Guarantee Trustee (each, an "Indemnified Person") for, and to hold
each Indemnified Person harmless against, any


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<PAGE>   13

loss, liability or expense incurred without negligence, willful misconduct or
bad faith on the part of the Indemnified Person, arising out of or in connection
with the acceptance or administration of this Guarantee Agreement, including the
costs and expenses of defending itself against any claim or liability in
connection with the exercise or performance of any of its powers or duties
hereunder.

       The Guarantee Trustee will not claim or exact any lien or charge on any
Guarantee Payments as a result of any amount due to it under this Guarantee
Agreement.

       The provisions of this Section 3.3 shall survive the termination of this
Guarantee Agreement or the resignation or removal of the Guarantee Trustee.

                                   ARTICLE IV
                                GUARANTEE TRUSTEE

       SECTION 4.1. GUARANTEE TRUSTEE; ELIGIBILITY.

       (a) There shall at all times be a Guarantee Trustee which shall:

              (i) not be an Affiliate of the Guarantor; and

              (ii) be a Person that is eligible pursuant to the Trust Indenture
       Act to act as such and has a combined capital and surplus of at least
       $50,000,000, and shall be a corporation meeting the requirements of
       Section 310(a) of the Trust Indenture Act. If such corporation publishes
       reports of condition at least annually, pursuant to law or to the
       requirements of its supervising or examining authority, then, for the
       purposes of this Section 4.1 and to the extent permitted by the Trust
       Indenture Act, the combined capital and surplus of such corporation shall
       be deemed to be its combined capital and surplus as set forth in its most
       recent report of condition so published.

       (b) If at any time the Guarantee Trustee shall cease to be eligible to so
act under Section 4.1(a), the Guarantee Trustee shall immediately resign in the
manner and with the effect set out in Section 4.2.

       (c) If the Guarantee Trustee has or shall acquire any "conflicting
interest" within the meaning of Section 310(b) of the Trust Indenture Act, the
Guarantee Trustee and Guarantor shall in all respects comply with the provisions
of Section 310(b) of the Trust Indenture Act.

       SECTION 4.2. APPOINTMENT, REMOVAL AND RESIGNATION OF THE GUARANTEE
TRUSTEE.

       (a) Subject to Section 4.2(c), the Guarantee Trustee may be appointed or
removed at any time by the action of the Holders of a Majority in Liquidation
Amount of the Trust Preferred Securities delivered to the Guarantee Trustee and
the Guarantor (i) for cause or (ii) if a Debenture Event of Default (as defined
in the Trust Agreement) shall have occurred and be continuing at any time.

       (b) Subject to Section 4.2(c), the Guarantee Trustee may resign from
office (without need for prior or subsequent accounting) by giving written
notice thereof to the Holders and the


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<PAGE>   14

Guarantor and by appointing a successor Guarantee Trustee. The Guarantee Trustee
shall appoint a successor by requesting from at least three Persons meeting the
requirements of Section 4.1(a) their expenses and charges to serve as the
Guarantee Trustee, and selecting the Person who agrees to the lowest expenses
and charges.

       (c) The Guarantee Trustee appointed hereunder shall hold office until a
Successor Guarantee Trustee shall have been appointed and shall have accepted
such appointment. No removal or resignation of a Guarantee Trustee shall be
effective until a Successor Guarantee Trustee has been appointed and has
accepted such appointment by written instrument executed by such Successor
Guarantee Trustee and delivered to the Guarantor and, in the case of any
resignation, the resigning Guarantee Trustee.

       (d) If no Successor Guarantee Trustee shall have been appointed and
accepted appointment as provided in this Section 4.2 within 60 days after
delivery to the Holders and the Guarantor of a notice of resignation, the
resigning Guarantee Trustee may petition, at the expense of the Guarantor, any
court of competent jurisdiction for appointment of a Successor Guarantee
Trustee. Such court may thereupon, after prescribing such notice, if any, as it
may deem proper, appoint a Successor Guarantee Trustee.

       (e) If a resigning Guarantee Trustee shall fail to appoint a successor,
or if a Guarantee Trustee shall be removed or become incapable of acting as
Guarantee Trustee and a replacement shall not be appointed prior to such
resignation or removal, or if a vacancy shall occur in the office of Guarantee
Trustee for any cause, the Holders of the Trust Preferred Securities, by the
action of the Holders of record of not less than 25% in aggregate Liquidation
Amount (as defined in the Trust Agreement) of the Trust Preferred Securities
then Outstanding (as defined in the Trust Agreement) delivered to such Guarantee
Trustee, may appoint a Successor Guarantee Trustee or Trustees. If no successor
Guarantee Trustee shall have been so appointed by the Holders of the Trust
Preferred Securities and accepted appointment, any Holder, on behalf of such
Holder and all others similarly situated, or any other Guarantee Trustee, may
petition any court of competent jurisdiction for the appointment of a successor
Guarantee Trustee.

                                    ARTICLE V
                                    GUARANTEE

       SECTION 5.1. GUARANTEE.

       The Guarantor irrevocably and unconditionally agrees to pay in full to
the Holders the Guarantee Payments (without duplication of amounts theretofore
paid by or on behalf of the Issuer Trust), as and when due, regardless of any
defense, right of set-off or counterclaim that the Issuer Trust may have or
assert, except the defense of payment. 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 Trust to pay such amounts
to the Holders.

       SECTION 5.2. WAIVER OF NOTICE AND DEMAND.

       The Guarantor hereby waives notice of acceptance of this Guarantee
Agreement and of any liability to which it applies or may apply, presentment,
demand for payment, any right to require a proceeding first against the
Guarantee Trustee, the Issuer Trust or any other Person


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<PAGE>   15

before proceeding against the Guarantor, protest, notice of nonpayment, notice
of dishonor, notice of redemption and all other notices and demands.

       SECTION 5.3. OBLIGATIONS NOT AFFECTED.

       The obligations, covenants, agreements and duties of the Guarantor under
this Guarantee Agreement 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 Trust of any express or implied
agreement, covenant, term or condition relating to the Trust Preferred
Securities to be performed or observed by the Issuer Trust;

       (b) the extension of time for the payment by the Issuer Trust of any
portion of the Distributions (other than an extension of time for payment of
Distributions that results from the extension of any interest payment period on
the Debentures as provided in the Indenture), Redemption Price, Liquidation
Distribution or any other sums payable under the terms of the Trust Preferred
Securities or the extension of time for the performance of any other obligation
under, arising out of, or in connection with, the Trust Preferred Securities;

       (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 Trust Preferred
Securities, or any action on the part of the Issuer Trust granting indulgence or
extension of any kind;

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

       (e) any invalidity of, or defect or deficiency in, the Trust Preferred
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 (other than payment of
the underlying obligation), it being the intent of this Section 5.3 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
the consent of, the Guarantor with respect to the happening of any of the
foregoing.

       SECTION 5.4. RIGHTS OF HOLDERS.

       The Guarantor expressly acknowledges that: (i) this Guarantee Agreement
will be deposited with the Guarantee Trustee to be held for the benefit of the
Holders; (ii) the Guarantee Trustee has the right to enforce this Guarantee
Agreement on behalf of the Holders; (iii) the


                                       12
<PAGE>   16

Holders of a Majority in Liquidation Amount of the Trust Preferred Securities
have the right to direct the time, method and place of conducting any proceeding
for any remedy available to the Guarantee Trustee in respect of this Guarantee
Agreement or exercising any trust or power conferred upon the Guarantee Trustee
under this Guarantee Agreement; and (iv) any Holder may institute a legal
proceeding directly against the Guarantor to enforce its rights under this
Guarantee Agreement without first instituting a legal proceeding against the
Guarantee Trustee, the Issuer Trust or any other Person.

       SECTION 5.5. GUARANTEE OF PAYMENT.

       This Guarantee Agreement creates a guarantee of payment and not of
collection. This Guarantee Agreement will not be discharged except by payment of
the Guarantee Payments in full (without duplication of amounts theretofore paid
by the Issuer Trust) or upon the distribution of Debentures to Holders as
provided in the Trust Agreement.

       SECTION 5.6. SUBROGATION.

       The Guarantor shall be subrogated to all rights (if any) of the Holders
against the Issuer Trust in respect of any amounts paid to the Holders by the
Guarantor under this Guarantee Agreement; 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 Guarantee Agreement, if, at the time of any such
payment, any amounts are due and unpaid under this Guarantee Agreement. 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 5.7. INDEPENDENT OBLIGATIONS.

       The Guarantor acknowledges that its obligations hereunder are independent
of the obligations of the Issuer Trust with respect to the Trust Preferred
Securities and that the Guarantor shall be liable as principal and as debtor
hereunder to make Guarantee Payments pursuant to the terms of this Guarantee
Agreement notwithstanding the occurrence of any event referred to in subsections
(a) through (g), inclusive, of Section 5.3 hereof.

                                   ARTICLE VI
                           COVENANTS AND SUBORDINATION

       SECTION 6.1. SUBORDINATION.

       The obligations of the Guarantor under this Guarantee Agreement will
constitute unsecured obligations of the Guarantor and will rank subordinate and
junior in right of payment to all Senior Debt (as defined in the Indenture) of
the Guarantor to the extent and in the manner set forth in the Indenture with
respect to the Debentures, and the provisions of Article Eighteen of the
Indenture will apply, mutatis mutandis, to the obligations of the Guarantor
hereunder. The obligations of the Guarantor hereunder do not constitute Senior
Debt (as defined in the Indenture) of the Guarantor.


                                       13
<PAGE>   17

       SECTION 6.2. PARI PASSU GUARANTEES.

       The obligations of the Guarantor under this Guarantee Agreement shall
rank pari passu with the obligations of the Guarantor under (i) any similar
guarantee agreements issued by the Guarantor on behalf of the holders of
preferred or Trust Preferred Securities issued by any business trust, (ii) the
Indenture and the Debt Securities (as defined therein) issued thereunder; and
(iii) any other security, guarantee or other agreement or obligation that is
expressly stated to rank pari passu with the obligations of the Guarantor under
this Guarantee Agreement or with any obligation that ranks pari passu with the
obligations of the Guarantor under this Guarantee Agreement.

                                   ARTICLE VII
                                   TERMINATION

       SECTION 7.1. TERMINATION.

       This Guarantee Agreement shall terminate and be of no further force and
effect upon (i) full payment of the Redemption Price of all Trust Preferred
Securities, (ii) the distribution of Debentures to the Holders in exchange for
all of the Trust Preferred Securities or (iii) full payment of the amounts
payable in accordance with Article IX of the Trust Agreement upon liquidation of
the Issuer Trust. Notwithstanding the foregoing, this Guarantee Agreement will
continue to be effective or will be reinstated, as the case may be, if at any
time any Holder is required to repay any sums paid with respect to Trust
Preferred Securities or this Guarantee Agreement.

                                  ARTICLE VIII
                                  MISCELLANEOUS

       SECTION 8.1. SUCCESSORS AND ASSIGNS.

       All guarantees and agreements contained in this Guarantee Agreement shall
bind the successors, assigns, receivers, trustees and representatives of the
Guarantor and shall inure to the benefit of the Holders of the Trust Preferred
Securities then outstanding. Except in connection with a consolidation, merger
or sale involving the Guarantor that is permitted under Article Eight of the
Indenture and pursuant to which the successor or assignee agrees in writing to
perform the Guarantor's obligations hereunder, the Guarantor shall not assign
its obligations hereunder, and any purported assignment other than in accordance
with this provision shall be void.

       SECTION 8.2. AMENDMENTS.

       Except with respect to any changes that do not adversely affect the
rights of the Holders in any material respect (in which case no consent of the
Holders will be required), this Guarantee Agreement may only be amended with the
prior approval of the Holders of not less than a Majority in Liquidation Amount
of the Trust Preferred Securities. The provisions of Article VI of the Trust
Agreement concerning meetings of the Holders shall apply to the giving of such
approval.


                                       14
<PAGE>   18

       SECTION 8.3. NOTICES.

       Any notice, request or other communication required or permitted to be
given hereunder shall be in writing, duly signed by the party giving such
notice, and delivered, telecopied or mailed by first class mail as follows:

       (a) if given to the Guarantor, to the address or telecopy number set
forth below or such other address or telecopy number as the Guarantor may give
notice to the Guarantee Trustee and the Holders:

              IndyMac Bancorp, Inc.
              155 North Lake Avenue Pasadena, CA 91101
              Attention:__________________
              Telecopy:  (626) 535-8203

       (b) if given to the Guarantee Trustee, to the address or telecopy number
set forth below or such other address or telecopy number as the Guarantee
Trustee may give notice to the Guarantor and Holders:

              The Bank of New York
              101 Barclay Street
              New York, New York 10286
              Attention: Corporate Trust Division
              Telecopy: (212) 815-5915

              with a copy to:

              IndyMac Capital Trust I

              c/o IndyMac Bancorp, Inc.
              155 North Lake Avenue Pasadena, CA 91101
              Attention:__________________
              Telecopy:  (626) 535-8203

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

       All notices hereunder 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 8.4. BENEFIT.

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


                                       15
<PAGE>   19

       SECTION 8.5. GOVERNING LAW.

       THIS GUARANTEE AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE
WITH THE LAWS OF THE STATE OF NEW YORK.

       SECTION 8.6. COUNTERPARTS.

       This instrument may be executed in any number of counterparts, each of
which so executed shall be deemed to be an original, but all such counterparts
shall together constitute but one and the same instrument.


                                       16
<PAGE>   20

       IN WITNESS WHEREOF, the parties hereto have executed this Guarantee
Agreement as of the day and year first above written.

                                        INDYMAC BANCORP, INC.,
                                         as Guarantor



                                        By:
                                           -------------------------------------
                                           Name:
                                           Title:


                                        THE BANK OF NEW YORK,
                                         as Guarantee Trustee



                                        By:
                                           -------------------------------------
                                           Name:
                                           Title:


                                       17