<PAGE>   1

                     WASHINGTON MUTUAL FINANCE CORPORATION

                                       AND

                        THE BANK OF NEW YORK, AS TRUSTEE

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

                             Senior Debt Securities

                                    Indenture

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

                            Dated as of June 8, 2000



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        INDENTURE, dated as of June 8, 2000 (the "Indenture"), between
WASHINGTON MUTUAL FINANCE CORPORATION, a corporation duly organized and
existing under the laws of the State of Delaware (herein called the "Company"),
having its principal offices at 8900 Grand Oak Circle, Tampa, Florida
33637-1050, and THE BANK OF NEW YORK, a New York banking corporation, as Trustee
(herein called the "Trustee").

                             RECITALS OF THE COMPANY

        The Company has duly authorized the execution and delivery of this
Indenture to provide for the issuance from time to time of its unsecured
debentures, notes or other obligations for money so borrowed (herein called the
"Securities"), to be issued in one or more series as in this Indenture provided.

        All things necessary to make this Indenture a valid agreement of the
Company, in accordance with its terms, have been done.

                   NOW, THEREFORE, THIS INDENTURE WITNESSETH:

        For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually covenanted and agreed, for the
equal and proportionate benefit of all Holders of the Securities or of any
series thereof, as follows:

PARAGRAPH A. INCORPORATION BY REFERENCE

        Articles I through XIV of the Washington Mutual Finance Corporation.
Standard Multiple-Series Indenture Provisions dated as of June __, 1999 (herein
called the "Standard Provisions"), a copy of which is attached hereto as Annex
"A", are hereby incorporated herein by reference with the same force and effect
as though fully set out herein.

PARAGRAPH B. ADDITIONAL PROVISIONS

        1.     Section 1.11 of the Standard Provisions is hereby amended by
inserting ", holders of Senior Debt" after the word "hereunder" on the third
line thereof.

        2.     Section 2.2 of the Standard Provisions is hereby amended by
deleting the words "[full name of Trustee] " and inserting the words "The Bank
of New York."

        3.     Section 1.5, subsection (b), of the Standard Provisions is hereby
amended by deleting the words "the address of its principal office specified in
the first paragraph of this instrument" and inserting the words 1201 Third
Avenue, Suite 1500, Seattle, Washington 98101, Attention: Executive Vice
President and General Counsel."

        4.     Section 6.14 of the Standard Provisions is hereby amended by
deleting the words "[full name of Trustee]" and inserting the words "The Bank
of New York."

        5.     The following provision, which constitutes part of this
Indenture, is numbered to conform with the format of the Standard Provisions.

               Section 6.15. Corporate Trust Office. At the date of this
        Indenture, the Corporate Trust Office of the Trustee is located at 101
        Barclay Street, New York, New York 10286.



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        IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed, and their respective corporate seals to be hereunto affixed and
attested, all as of the day and year first above written.

                                       WASHINGTON MUTUAL FINANCE CORPORATION





                                       By                /s/
                                          --------------------------------------
                                          Authorized Signatory



[SEAL]

Attest



              /s/
------------------------------
Assistant Secretary



                                       THE BANK OF NEW YORK,
                                       as Trustee


                                       By
                                          --------------------------------------
                                          Title: Authorized Signatory

[SEAL]

Attest



-------------------------------
Title: Assistant Vice President




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STATE OF WASHINGTON  )
                           ) ss
COUNTY OF KING       )

        On the 8th day of June, 2000, before me personally came Richard D. Lodge
to me known, who, being by me duly sworn, did depose and say that he is Senior
Vice President of WASHINGTON MUTUAL FINANCE CORPORATION, one of the corporations
described in and which executed the foregoing instrument; that he knows the seal
of said corporation; that the seal affixed to said instrument is such corporate
seal; that it was so affixed by authority of the Board of Directors of said
corporation, and that he signed his name thereto by like authority.


                                                /s/
                                       -----------------------------------------
                                       Notary Public









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        IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed, and their respective corporate seals to be hereunto affixed and
attested, all as of the day and year first above written.

                                       WASHINGTON MUTUAL FINANCE CORPORATION



                                       By:
                                           -------------------------------------
                                           Authorized Signatory



[SEAL]

Attest



------------------------------
Secretary



                                       THE BANK OF NEW YORK,
                                       as Trustee



                                       By        /s/
                                           -------------------------------------
                                           Title:  Authorized Signatory

[SEAL]

Attest


    /s/
------------------------------
Title: Assistant Secretary






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STATE OF NEW YORK         )
                          ) ss
COUNTY OF NEW YORK        )

        On the 7th day of June, 2000, before me personally came Stephen J.
Giorlando to me known, who, being by me duly sworn, did depose and say that he
is Vice President of THE BANK OF NEW YORK, one of the corporations described in
and which executed the foregoing instrument; that he knows the seal of said
corporation; that the seal affixed to said instrument is such corporate seal;
that it was so affixed by authority of the Board of Directors of said
corporation, and that he signed his name thereto by like authority.



                                                        /s/
                                       -----------------------------------------
                                       Notary Public






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