<PAGE>

                                   EXHIBIT 4.10

        [If the Holder of this Security is a depository, such as The Depository
Trust Company ("DTC") or a nominee of DTC, this Security is a Global Security
and insert the following two legends:

        THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITORY (AS
DEFINED IN THE INDENTURE) OR A NOMINEE THEREOF. THIS GLOBAL SECURITY IS
EXCHANGEABLE FOR SECURITIES REGISTERED IN THE NAME OF A PERSON OTHER THAN THE
DEPOSITORY OR ITS NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE
INDENTURE AND, UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR
SECURITIES IN DEFINITIVE FORM, THIS GLOBAL SECURITY MAY NOT BE TRANSFERRED
EXCEPT AS A WHOLE BY THE DEPOSITORY TO A NOMINEE OF THE DEPOSITORY, OR BY A
NOMINEE OF THE DEPOSITORY TO THE DEPOSITORY OR ANOTHER NOMINEE OF THE
DEPOSITORY, OR BY THE DEPOSITORY OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITORY
OR A NOMINEE OF SUCH SUCCESSOR DEPOSITORY.

        UNLESS THE SECURITY IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF [THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"),] TO THE COMPANY (AS
DEFINED BELOW) OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT,
AND ANY SECURITY ISSUED IS REGISTERED IN THE NAME OF [CEDE & CO. OR IN] SUCH
[OTHER] NAME AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF [THE DEPOSITORY]
[DTC] (AND ANY PAYMENT IS MADE TO [CEDE & CO. OR TO] SUCH [OTHER] ENTITY AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF [THE DEPOSITORY] [DTC]), ANY
TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON
IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF[, CEDE & CO.,] HAS AN
INTEREST HEREIN.]

        [If this security is an Original Issue Discount Security, insert -- FOR
PURPOSES OF SECTION 1273 AND 1275 OF THE UNITED STATES INTERNAL REVENUE CODE,
THE AMOUNT OF ORIGINAL ISSUE DISCOUNT ON THIS SECURITY IS ___% OF ITS PRINCIPAL
AMOUNT, THE ISSUE DATE IS __________, AND THE YIELD TO MATURITY IS ___%. [[THE
METHOD USED TO DETERMINE THE AMOUNT OF ORIGINAL ISSUE DISCOUNT APPLICABLE TO THE
SHORT ACCRUAL PERIOD OF __________ TO __________, IS ___% OF THE PRINCIPAL
AMOUNT OF THIS SECURITY.]]

NO. ___  $__________

                               SAFECO CORPORATION

                             [Designation of Series]

        SAFECO Corporation, a Washington corporation (hereinafter called the
"Company", which term includes any successor corporation under the Indenture
referred to below), for value received, hereby promises to pay to
______________, or registered assigns, the principal sum of



<PAGE>

______________ Dollars ($________) on ______________,____ [If the Security is to
bear interest prior to Maturity, insert -- , and to pay interest thereon from
______ or from the most recent Interest Payment Date to which interest has been
paid or duly provided for, semiannually on _________ and __________ in each
year, commencing _____________, [If the Security is to bear interest at a fixed
rate, insert -- at the rate of ___% per annum] [If the Security is to bear
interest at an adjustable rate, insert -- at a rate per annum computed or
determined in accordance with the provisions below], until the principal hereof
is paid or made available for payment [If applicable, insert --, and (to the
extent that the payment of such interest shall be legally enforceable) at the
rate of ___% per annum on any overdue principal and premium and on any overdue
installment of interest from the dates such amounts are due until they are paid
or made available for payment and such interest shall be payable on demand]. [If
applicable, insert -- Interest on this Security shall be computed on the basis
of a 360-day year of twelve 30-day months. If any Interest Payment Date or the
maturity date falls on a day that is not a Business Day, the required payment
shall be made on the next Business Day as if it were made on the date such
payment was due and no interest shall accrue on the amount so payable for the
period from and after such Interest Payment Date or the maturity date, as the
case may be, to such next Business Day.] The interest so payable and punctually
paid or duly provided for on any Interest Payment Date will, as provided in such
Indenture, be paid to the Person in whose name this Security (or one or more
Predecessor Securities) is registered at the close of business on the regular
record date for such interest, which shall be ______________ or ______________
(whether or not a Business Day), as the case may be, next preceding such
Interest Payment Date. Any such interest which is payable but not punctually
paid or duly provided for on any Interest Payment Date shall forthwith cease to
be payable to the registered Holder hereof on the relevant regular record date
by virtue or having been such holder, and may be paid to the Person in whose
name this Security (or one or more Predecessor Securities) is registered at the
close of business on a subsequent special record date (which shall be at least
10 days before the payment date) for the payment of such defaulted interest to
be fixed by the Company, notice whereof shall be given to the Holders of
Securities of this series not less than 10 days prior to such Special Record
Date, or may be paid at any time in any other lawful manner not inconsistent
with the requirements of any securities exchange on which the Securities may be
listed, and upon such notice as may be required by such exchange, all as more
fully provided in such Indenture.

        [If the Security is not to bear interest prior to Maturity, insert - -
The principal of this Security shall not bear interest except in the case of a
default in payment of principal upon acceleration or redemption or at the Stated
Maturity and in such case the overdue principal of this Security shall bear
interest at the rate of ___% per annum (to the extent that the payment of such
interest shall be legally enforceable), which shall accrue from the date of such
default in payment to the date payment of such principal has been made or duly
provided for. Interest on any overdue principal shall be payable on demand. Any
such interest on any overdue principal that is not so paid on demand shall bear
interest at the rate of ___% per annum (to the extent that the payment of such
interest shall be legally enforceable), which shall accrue from the date of such
demand for payment to the date payment of such interest has been made or duly
provided for, and such interest shall also be payable on demand.]

        Payment of the principal of and [If applicable, insert - - any such]
interest on this Security will be made at the office or agency of the Company
maintained for that purpose in The Borough of Manhattan, The City of New York,
in such coin or currency of the United States of America as at the time of
payment is legal tender for payment of public and private debts [If applicable,
insert -- ; provided, however, that, at the option of the Company, interest may
be paid by check mailed to the address of the Person entitled thereto as such
address shall appear in the Security Register;] [If



                                      -2-
<PAGE>

applicable, insert -- provided, further, that payment to [DTC or] any
[successor] depository may be made by wire transfer to the account designated by
[DTC or] such [successor] depository in writing].

        This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities"), issued and to be issued in one or more
series under an Indenture, dated as of __________, 20__ (herein called, together
with all indentures supplemental thereto, the "Indenture"), between the Company
and ___________________, as Trustee (herein called the "Trustee", which term
includes any successor trustee under the Indenture), to which Indenture and all
indentures supplemental thereto reference is hereby made for a statement of the
respective rights, limitations of rights, duties and immunities thereunder of
the Company, the Trustee and the Holders of the Securities, and of the terms
upon which the Securities are, and are to be, authenticated and delivered. This
Security is one of the series designated on the face hereof [, initially limited
(subject to exceptions provided in the Indenture) to the aggregate principal
amount of $_________].

        Subject to and upon compliance with the provisions of the Indenture, the
Holder of this Security is entitled, at his option, at any time on or before the
close of business on _________ __, _____, or in case this Security or a portion
hereof is called for redemption, then in respect of this Security or such
portion hereof until and including, but (unless the Company defaults in making
the payment due upon redemption) not after, the close of business on the
Business Day immediately preceding the Redemption Date, to convert this Security
(or any portion of the principal amount hereof which is $1,000 or an integral
multiple thereof or in the case of Bearer Securities $5,000 or an integral
multiple of $5,000), at the principal amount hereof, or of such portion, into
fully paid and non-assessable shares (calculated as to each conversion to the
nearest 1/100 of a share) of Common Stock of the Company at a conversion price
equal to $______ aggregate principal amount of Securities for each share of
Common Stock (or at the current adjusted conversion price if an adjustment has
been made as provided in the Indenture) by surrender of this Security, duly
endorsed or assigned to the Company or in blank, to the Company at its office or
agency in _______________, accompanied by written notice to the Company that the
Holder hereof elects to convert this Security, or if less than the entire
principal amount hereof is to be converted, the portion hereof to be converted
(in the case of Bearer Securities, any Bearer Security surrendered for
conversion must be accompanied by all Coupons maturing subsequent to the date of
surrender of such Bearer Security for conversion or the amount of any such
missing Coupons will be deducted from the amount due on such Security used to
determine the amount of shares of Common Stock such Bearer Security may be
converted into), and, in case such surrender shall be made during the period
from the close of business on any Regular Record Date next preceding any
Interest Payment Date to the opening of business on such Interest Payment Date
(unless this Security or the portion thereof being converted has been called for
redemption on a Redemption Date such that the conversion right of this Security
would terminate between such Regular Record Date and the close of business on
such Interest Payment Date), also accompanied by payment in funds reasonably
acceptable to the Company of an amount equal to the interest payable on such
Interest Payment Date on the principal amount of this Security then being
converted (with similar provision to be made for Bearer Securities). In case
surrender of this Security for conversion shall be made during the period from
the close of business on any Regular Record Date next preceding any Interest
Payment Date to the opening of business on such Interest Payment Date and if
this Security or portion hereof has been called for redemption on a Redemption
Date with the consequence that the conversion right of this Security would
terminate between such Regular Record Date and the close of business on such
Interest Payment Date, then the Holder of this Security will be entitled to
receive the interest accruing hereon from the Interest Payment Date next
preceding the date of such conversion to



                                      -3-
<PAGE>

such succeeding Interest Payment Date and shall not be required to pay such
interest upon surrender of this Security for conversion. Subject to the
aforesaid requirement for payment and, in the case of a conversion after the
Regular Record Date next preceding any Interest Payment Date and on or before
such Interest Payment Date, to the right of the Holder of this Security (or any
Predecessor Security) of record at such Regular Record Date to receive an
installment of interest (with certain exceptions provided in the Indenture), no
payment or adjustment is to be made on conversion for interest accrued hereon or
for dividends on the Common Stock issued on conversion. No fractions of shares
or scrip representing fractions of shares will be issued on conversion, but
instead of any fractional interest the Company shall pay a cash adjustment as
provided in the Indenture. The conversion price is subject to adjustment as
provided in the Indenture. In addition, the Indenture provides that in case of
certain consolidations or mergers to which the Company is a party or the
transfer of substantially all of the assets of the Company, the Indenture shall
be amended, without the consent of any Holders of Securities, so that this
Security, if then outstanding, will be convertible thereafter, during the period
this Security shall be convertible as specified above, only into the kind and
amount of securities, cash and other property receivable upon the consolidation,
merger or transfer or conveyance by a holder of the number of shares of Common
Stock into which this Security might have been converted immediately prior to
such consolidation, merger or transfer or conveyance (assuming such holder of
Common Stock failed to exercise any rights of election and received per share
the kind and amount received per share by a plurality of nonelecting shares).

        The indebtedness evidenced by the Securities is, to the extent provided
in the Indenture, subordinate and subject in right of payment to the prior
payment in full of all indebtedness and obligations of the Company as are
defined in the Indenture as "Senior Indebtedness," and this Security is issued
subject to the provisions of the Indenture with respect thereto, and each Holder
of this Security, by accepting the same, agrees to and shall be bound by such
provisions. Each Holder of this Security, by accepting the same, agrees that
each holder of Senior Indebtedness, whether created or acquired before or after
the issuance of this Security, shall be deemed conclusively to have relied on
such subordination provisions in acquiring and continuing to hold, or in
continuing to hold, such Senior Indebtedness.

        [If the Security is not an Original Issue Discount Security, insert --
If an Event of Default with respect to the Securities shall occur and be
continuing, the principal of the Securities may be declared due and payable in
the manner and with the effect provided in the Indenture.]

        [If the Security is an Original Issue Discount Security, insert - - If
an Event of Default with respect to Securities of this series shall occur and be
continuing, an amount of principal of the Securities of this series may be
declared due and payable in the manner and with the effect provided in the
Indenture. Such amount shall be equal to [insert formula for determining the
amount]. Upon payment (i) of the amount of principal so declared due and payable
and (ii) of interest on any overdue principal, premium and interest (in each
case to the extent that the payment of such interest shall be legally
enforceable), all of the Company's obligations in respect of the payment of the
principal of and premium and interest, if any, on the Securities of this series
shall terminate.]

        [If applicable, insert -- The Securities may not be redeemed prior to
the Stated Maturity.]

        [If applicable, insert -- The Securities are not subject to any sinking
fund.]



                                      -4-
<PAGE>

        [If applicable, insert -- The Securities are subject to redemption [ (l)
[If applicable, insert -- on __________ in any year commencing with the year
_____ and ending with the year _____ through operation of the sinking fund for
this series at a Redemption Price equal to 100% of the principal amount, and
(2)] [If applicable, insert -- at any time [on or after __________], as a whole
or in part, at the election of the Company, at the following Redemption Prices
(expressed as percentages of the principal amount): if redeemed on or before
__________, ___% and if redeemed during the 12-month period beginning __________
of the years indicated at the Redemption Prices indicated below:

                    Year               Redemption Price
                    ----               ----------------

and thereafter at a Redemption Price equal to ___% of the principal amount,
together in the case of any such redemption [If applicable, insert -- (whether
through operation of the sinking fund or otherwise)] with accrued interest to
the Redemption Date; provided, however, that installments of interest on this
Security whose Stated Maturity is on or prior to such Redemption Date will be
payable to the Holder of this Security, or one or more Predecessor Securities,
of record at the close of business on the relevant Record Dates referred to on
the face hereof, all as provided in the Indenture.]

        [If applicable, insert -- The Securities are subject to redemption (1)
on __________ in any year commencing with the year _____ and ending with the
year _____ through operation of the sinking fund for this series at the
Redemption Prices for redemption through operation of the sinking fund
(expressed as percentages of the principal amount) set forth in the table below,
and (2) at any time [on or after __________], as a whole or in part, at the
election of the Company, at the Redemption Prices for redemption otherwise than
through operation of the sinking fund (expressed as percentages of the principal
amount) set forth in the table below: if redeemed during the 12-month period
beginning __________ of the years indicated below:

<TABLE>
<CAPTION>
                                                       Redemption Price for
                     Redemption Price for           Redemption Otherwise than
                 Redemption through Operation        through Operation of the
    Year             of the Sinking Fund                   Sinking Fund
    ----         ----------------------------        ------------------------
<S>              <C>                                 <C>
</TABLE>

and thereafter at a Redemption Price equal to ___% of the principal amount,
together in the case of any such redemption (whether through operation of the
sinking fund or otherwise) with accrued interest to the Redemption Date;
provided, however, that installments of interest on this Security whose Stated
Maturity is on or prior to such Redemption Date will be payable to the Holder of
this Security, or one or more Predecessor Securities, of record at the close of
business on the relevant Record Dates referred to on the face hereof, all as
provided in the Indenture.]

        [If applicable, insert -- Notwithstanding the foregoing, the Company may
not, prior to __________, redeem any Securities as contemplated by [Clause (2)
of] the preceding paragraph as a part of, or in anticipation of, any refunding
operation by the application, directly or indirectly, of



                                      -5-
<PAGE>

moneys borrowed having an interest cost to the Company (calculated in accordance
with generally accepted financial practice) of less than ___% per annum.]

        [If applicable, insert -- The sinking fund for the Securities provides
for the redemption on __________ in each year, beginning with the year _____ and
ending with the year _____, of [not less than] $__________ [("mandatory sinking
fund") and not more than $__________] aggregate principal amount of the
Securities of this series. [The Securities acquired or redeemed by the Company
otherwise than through [mandatory] sinking fund payments may be credited against
subsequent [mandatory] sinking fund payments otherwise required to be made in
the [describe order].]]

        [If applicable, insert -- Notice of redemption will be given by mail to
Holders of Securities, not less than 30 nor more than 60 days prior to the
Redemption Date, all as provided in the Indenture.]

        In the event of [If applicable, insert -- redemption or] conversion of
this Security in part only, a new Security or Securities for the [If applicable,
insert -- unredeemed or] unconverted portion hereof shall be issued in the name
of the Holder hereof upon the cancellation hereof.

        The Indenture contains provisions permitting, with certain exceptions as
therein provided, the amendment thereof and the modification of the rights and
obligations of the Company and the rights of the Holders of the Securities of
each series issued under the Indenture at any time by the Company and the
Trustee with the written consent of the Holders of not less than a majority in
aggregate principal amount of the Securities at the time Outstanding of each
series affected thereby. The Indenture also contains provisions permitting the
Holders of specified percentages in aggregate principal amount of the Securities
of any series at the time Outstanding, on behalf of the Holders of all
Securities of such series, to waive compliance by the Company with certain
provisions of the Indenture and certain past defaults under the Indenture and
their consequences. Any such consent or waiver by the Holder of this Security
shall be conclusive and binding upon such Holder and upon all future Holders of
this Securities and of any Securities issued upon the registration of transfer
hereof or in exchange herefor or in lieu hereof, whether or not notation of such
consent or waiver is made upon this Security.

        No reference herein to the Indenture and no provision of this Security
or of the Indenture shall alter or impair the obligation of the Company, which
is absolute and unconditional, to pay the principal of and interest on this
Security, at the times, place and rate, and in the coin or currency, herein or
to convert this Security, and in the Indenture prescribed.

        As provided in the Indenture and subject to certain limitations set
forth therein and in this Security, the transfer of this Security may be
registered on the Security Register upon surrender of this Security for
registration of transfer at the office or agency of the Company maintained for
that purpose in any place where the principal of and interest on this Security
are payable, duly endorsed by, or accompanied by a written instrument of
transfer in form satisfactory to the Company and the Security Registrar duly
executed by, the Holder hereof or by his attorney duly authorized in writing,
and thereupon one or more new Securities of this series and of like tenor, of
authorized denominations and for the same aggregate principal amount, will be
issued to the designated transferee or transferees.

        [If applicable, insert -- The Securities are issuable only in registered
form [without coupons] in the denominations of $__________ and any integral
multiple thereof.] As provided in the Indenture and subject to certain
limitations set forth in the Indenture, and in this Security, the Securities are



                                      -6-
<PAGE>

exchangeable for a like aggregate principal amount of Securities of this series
in different authorized denominations, as requested by the Holders surrendering
the same.]

        No service charge shall be made for any such registration of transfer or
exchange, but the Company may require payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith, other than in
certain cases provided in the Indenture.

        Prior to due presentment of this Security for registration of transfer,
the Company, the Trustee and any agent of the Company or the Trustee may treat
the Person in whose name this Security is registered as the owner hereof for all
purposes, whether or not this Security be overdue, and neither the Company, the
Trustee nor any such agent shall be affected by notice to the contrary.

        [If applicable, insert -- The Indenture contains provisions whereby (i)
the Company may be discharged from its obligations with respect to the
Securities (subject to certain exceptions) or (ii) the Company may be released
from its obligations under specified covenants and agreements in the Indenture,
in each case if the Company irrevocably deposits with the Trustee money or
Government Obligations, or a combination thereof, in an amount sufficient,
without consideration of any reinvestment, to pay and discharge the entire
indebtedness on all Securities of this series, and satisfies certain other
conditions, all as more fully provided in the Indenture.]

        This Security shall be governed by and construed in accordance with the
laws of the State of New York applicable to agreements made or instruments
entered into, and in each case, performed in said State.

        All terms used in this Security without definition that are defined in
the Indenture shall have the meanings assigned to them in the Indenture.


                  [Remainder of Page Intentionally Left Blank]



                                      -7-
<PAGE>

        Unless the Certificate of Authentication hereon has been executed by or
on behalf of the Trustee under the Indenture by the manual signature of one of
its authorized officers, this Security shall not be entitled to any benefits
under the Indenture or be valid or obligatory for any purpose.

        IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed under its corporate seal.

                                        SAFECO CORPORATION

        [SEAL]

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


        ATTEST:

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



                          CERTIFICATE OF AUTHENTICATION

This is one of the Securities of the series designated therein referred to in
the within-mentioned Indenture.

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

                                        AS TRUSTEE

Dated:

                                        By:
                                           -------------------------------------
                                        Name:
                                        Title:
                                        as an Authorized Officer



                                      -8-