1


                  THE TRANSFER OF THIS AGREEMENT IS SUBJECT TO
                   CERTAIN PROVISIONS CONTAINED HEREIN AND TO
                          RESALE RESTRICTIONS UNDER THE
                       SECURITIES ACT OF 1933, AS AMENDED


                  STOCK OPTION AGREEMENT, dated October 3, 2000, between U.S.
Bancorp, a Delaware corporation ("Issuer"), and Firstar Corporation, a Wisconsin
corporation ("Grantee").

                              W I T N E S S E T H :
                              - - - - - - - - - -


                  WHEREAS, Grantee and Issuer have entered into an Agreement and
Plan of Merger of even date herewith (the "Merger Agreement"), which agreement
has been executed by the parties hereto immediately prior to this Stock Option
Agreement (this "Agreement"); and

                  WHEREAS, as a condition to Grantee's entering into the Merger
Agreement and in consideration therefor and for Grantee's entering into the
Firstar Option Agreement, Issuer has agreed to grant Grantee the Option (as
hereinafter defined);

                  NOW, THEREFORE, in consideration of the foregoing and the
mutual covenants and agreements set forth herein and in the Merger Agreement,
the parties hereto agree as follows:

                  1. (a) Issuer hereby grants to Grantee an unconditional,
irrevocable option (the "Option") to purchase, subject to the terms hereof, up
to 147,939,263 fully paid and nonassessable shares of Issuer's common stock, par
value $1.25 per share ("Common Stock"), at a price of $23.1875 per share (the
"Option Price"); provided, however, that in no event shall the number of shares
of Common Stock for which this Option is exercisable exceed 19.9% of the
Issuer's issued and outstanding shares of Common Stock without giving effect to
any shares subject to or issued pursuant to the Option. The number of shares of
Common Stock that may be received upon the exercise of the Option and the Option
Price are subject to adjustment as herein set forth.

                  (b) In the event that any additional shares of Common
Stock are either (i) issued or otherwise become outstanding after the date of
this Agreement (other than pursuant to this Agreement) or (ii) redeemed,
repurchased, retired or otherwise cease to be outstanding after the date of the
Agreement, the number of shares of Common Stock subject to the Option shall be
increased or decreased, as appropriate, so that, after such issuance, such
number equals 19.9% of the number of shares of Common Stock then issued and
outstanding without giving effect to any shares subject or issued pursuant to
the Option. Nothing contained in this Section 1(b) or elsewhere in this
Agreement shall be deemed to authorize Issuer or Grantee to breach any provision
of the Merger Agreement.

                  2. (a) The Holder (as hereinafter defined) may exercise the
Option, in whole or part, and from time to time, if, but only if, both an
Initial Triggering Event (as hereinafter de-




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fined) and a Subsequent Triggering Event (as hereinafter defined) shall have
occurred prior to the occurrence of an Exercise Termination Event (as
hereinafter defined), provided that the Holder shall have sent the written
notice of such exercise (as provided in Section 2(e)) within 90 days following
such Subsequent Triggering Event. Each of the following shall be an "Exercise
Termination Event": (i) the Effective Time (as defined in the Merger Agreement)
of the Merger; (ii) termination of the Merger Agreement in accordance with the
provisions thereof if such termination occurs prior to the occurrence of an
Initial Triggering Event, except a termination by Grantee pursuant to Section
8.1(d) of the Merger Agreement (unless the breach by Issuer giving rise to such
right of termination is non-volitional); or (iii) the passage of 12 months after
termination of the Merger Agreement if such termination follows the occurrence
of an Initial Triggering Event or is a termination by Grantee pursuant to
Section 8.1(d) of the Merger Agreement (unless the breach by Issuer giving rise
to such right of termination is non-volitional) (provided that if an Initial
Triggering Event continues or occurs beyond such termination and prior to the
passage of such 12-month period, the Exercise Termination Event shall be 12
months from the expiration of the Last Triggering Event but in no event more
than 18 months after such termination). The "Last Triggering Event" shall mean
the last Initial Triggering Event to expire. The term "Holder" shall mean the
holder or holders of the Option.

                  (b) The term "Initial Triggering Event" shall mean any of the
following events or transactions occurring after the date hereof: (i) Issuer or
any of its Subsidiaries (as defined in Rule 1-02 of Regulation S-X promulgated
by the Securities and Exchange Commission (the "SEC")) (each an "Issuer
Subsidiary"), without having received Grantee's prior written consent, shall
have entered into an agreement to engage in an Acquisition Transaction (as
hereinafter defined) with any person (the term "person" for purposes of this
Agreement having the meaning assigned thereto in Sections 3(a)(9) and 13(d)(3)
of the Securities Exchange Act of 1934, as amended (the "1934 Act"), and the
rules and regulations thereunder) other than Grantee or any of its Subsidiaries
(each a "Grantee Subsidiary") or the board of directors of Issuer shall have
recommended that the shareholders of Issuer approve or accept any Acquisition
Transaction. For purposes of this Agreement, "Acquisition Transaction" shall
mean (A) a merger or consolidation, or any similar transaction, involving Issuer
or Issuer Subsidiary, (B) a purchase, lease or other acquisition or assumption
of all or a substantial portion of the assets or deposits of Issuer or any
Issuer Subsidiary, (C) a purchase or other acquisition (including by way of
merger, consolidation, share exchange or otherwise) of securities representing
10% or more of the voting power of Issuer, or (D) any substantially similar
transaction; provided, however, that in no event shall any merger,
consolidation, purchase or similar transaction involving only the Issuer and one
or more Issuer Subsidiary or involving only any two or more of such Issuer
Subsidiaries, provided that any such transaction is not entered into in
violation of the terms of the Merger Agreement, be deemed to be an Acquisition
Transaction; (ii) Issuer or any Issuer Subsidiary, without having received
Grantee's prior written consent, shall have authorized, recommended, proposed or
publicly announced its intention to authorize, recommend or propose, to engage
in an Acquisition Transaction with any person other than Grantee or a Grantee
Subsidiary, or the board of directors of Issuer shall have publicly withdrawn or
modified, or publicly announced its interest to withdraw or modify, in any
manner adverse to Grantee, its recommendation that the shareholders of Issuer
approve the transactions contemplated by the Merger Agreement in anticipation of
engaging in an Acquisition Transaction; (iii) any person other than Grantee, any
Grantee Subsidiary or any Issuer Subsidiary acting in a fiduciary capacity in
the ordinary course of its business shall have acquired beneficial ownership or
the right to acquire beneficial ownership of 10% or

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more of the outstanding shares of Common Stock (the term "beneficial ownership"
for purposes of this Agreement having the meaning assigned thereto in Section
13(d) of the 1934 Act, and the rules and regulations thereunder); (iv) any
person other than Grantee or any Grantee Subsidiary shall have made a bona fide
proposal to Issuer or its shareholders by public announcement or written
communication that is or becomes the subject of public disclosure to engage in
an Acquisition Transaction; (v) after an overture is made by a third party to
Issuer or its shareholders to engage in an Acquisition Transaction, Issuer shall
have breached any covenant or obligation contained in the Merger Agreement and
such breach (A) would entitle Grantee to terminate the Merger Agreement and (B)
shall not have been cured prior to the Notice Date (as hereinafter defined); or
(vi) any person other than Grantee or any Grantee Subsidiary, other than in
connection with a transaction to which Grantee has given its prior written
consent, shall have filed an application or notice with the Federal Reserve
Board, or other federal or state bank regulatory authority, which application or
notice has been accepted for processing, for approval to engage in an
Acquisition Transaction.

                  (c) The term "Subsequent Triggering Event" shall mean either
of the following events or transactions occurring after the date hereof: (i) the
acquisition by any person of beneficial ownership of 20% or more of the
then-outstanding Common Stock; or (ii) the occurrence of the Initial Triggering
Event described Section 2(b)(i), except that the percentage referred to in
clause (C) shall be 20%.

                  (d) Issuer shall notify Grantee promptly in writing of the
occurrence of any Initial Triggering Event or Subsequent Triggering Event of
which it has notice (together, a "Triggering Event"), it being understood that
the giving of such notice by Issuer shall not be a condition to the right of the
Holder to exercise the Option.

                  (e) In the event the Holder is entitled to and wishes to
exercise the Option, it shall send to Issuer a written notice (the date of which
being herein referred to as the "Notice Date") specifying (i) the total number
of shares it will purchase pursuant to such exercise and (ii) a place and date
not earlier than three business days nor later than 60 business days from the
Notice Date for the closing of such purchase (the "Closing Date"); provided that
if prior notification to or approval of the Federal Reserve Board or any other
regulatory agency is required in connection with such purchase, the Holder shall
promptly file the required notice or application for approval and shall
expeditiously process the same and the period of time that otherwise would run
pursuant to this sentence shall run instead from the date on which any required
notification periods have expired or been terminated or such approvals have been
obtained and any requisite waiting period or periods shall have passed. Any
exercise of the Option shall be deemed to occur on the Notice Date relating
thereto.

                  (f) At the closing referred to in Section 2(e), the Holder
shall pay to Issuer the aggregate purchase price for the shares of Common Stock
purchased pursuant to the exercise of the Option in immediately available funds
by wire transfer to a bank account designated by Issuer, provided that failure
or refusal of Issuer to designate such a bank account shall not preclude the
Holder from exercising the Option.

                  (g) At such closing, simultaneously with the delivery of
immediately available funds as provided in Section 2(f), Issuer shall deliver to
the Holder a certificate or certificates

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representing the number of shares of Common Stock purchased by the Holder and,
if the Option should be exercised in part only, a new Option evidencing the
rights of the Holder thereof to purchase the balance of the shares purchasable
hereunder, and the Holder shall deliver to Issuer a copy of this Agreement and a
letter agreeing that the Holder will not offer to sell or otherwise dispose of
such shares in violation of applicable law or the provisions of this Agreement.

                  (h) Certificates for Common Stock delivered at a closing
hereunder may be endorsed with a restrictive legend that shall read
substantially as follows:

                  The transfer of the shares represented by this certificate is
                  subject to certain provisions of an agreement between the
                  registered holder hereof and Issuer and to resale restrictions
                  arising under the Securities Act of 1933, as amended. A copy
                  of such agreement is on file at the principal office of Issuer
                  and will be provided to the holder hereof without charge upon
                  receipt by Issuer of a written request therefor.

It is understood and agreed that: (i) the reference to the resale restrictions
of the Securities Act of 1933, as amended (the "1933 Act"), in the above legend
shall be removed by delivery of substitute certificate(s) without such reference
if the Holder shall have delivered to Issuer a copy of a letter from the staff
of the SEC, or an opinion of counsel, in form and substance reasonably
satisfactory to Issuer, to the effect that such legend is not required for
purposes of the 1933 Act; (ii) the reference to the provisions of this Agreement
in the above legend shall be removed by delivery of substitute certificate(s)
without such reference if the shares have been sold or transferred in compliance
with the provisions of this Agreement and under circumstances that do not
require the retention of such reference; and (iii) the legend shall be removed
in its entirety if the conditions in the preceding clauses (i) and (ii) are both
satisfied. In addition, such certificates shall bear any other legend as may be
required by law.

                  (i) Upon the giving by the Holder to Issuer of the written
notice of exercise of the Option provided for under Section 2(e) and the tender
of the applicable purchase price in immediately available funds, the Holder
shall be deemed, subject to the receipt of applicable regulatory approvals, to
be the holder of record of the shares of Common Stock issuable upon such
exercise, notwithstanding that the stock transfer books of Issuer shall then be
closed or that certificates representing such shares of Common Stock shall not
then be actually delivered to the Holder. Issuer shall pay all expenses, and any
and all United States federal, state and local taxes and other charges that may
be payable in connection with the preparation, issue and delivery of stock
certificates under this Section 2 in the name of the Holder or its assignee,
transferee or designee.

                  3. Issuer agrees: (a) that it shall at all times maintain,
free from preemptive rights, sufficient authorized but unissued or treasury
shares of Common Stock so that the Option may be exercised without additional
authorization of Common Stock after giving effect to all other options,
warrants, convertible securities and other rights to purchase Common Stock; (b)
that it will not, by charter amendment or through reorganization, consolidation,
merger, dissolution or sale of assets, or by any other voluntary act, avoid or
seek to avoid the observance or performance of any of the covenants,
stipulations or conditions to be observed or performed hereunder by Issuer; (c)
promptly to take all action as may from time to time be required (in-

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cluding (i) complying with all premerger notification, reporting and waiting
period requirements specified in 15 U.S.C. Section 18a and regulations
promulgated thereunder and (ii) in the event, under the Bank Holding Company Act
of 1956, as amended (the "BHCA"), or the Change in Bank Control Act of 1978, as
amended, or any state banking law, prior approval of or notice to the Federal
Reserve Board or to any state regulatory authority is necessary before the
Option may be exercised, cooperating fully with the Holder in preparing such
applications or notices and providing such information to the Federal Reserve
Board or such state regulatory authority as they may require) in order to permit
the Holder to exercise the Option and Issuer duly and effectively to issue
shares of Common Stock pursuant hereto; and (d) promptly to take all action
provided herein to protect the rights of the Holder against dilution.

                  4. This Agreement (and the Option granted hereby) are
exchangeable, without expense, at the option of the Holder, upon presentation
and surrender of this Agreement at the principal office of Issuer, for other
Agreements providing for Options of different denominations entitling the holder
thereof to purchase, on the same terms and subject to the same conditions as are
set forth herein, in the aggregate the same number of shares of Common Stock
purchasable hereunder. The terms "Agreement" and "Option" as used herein include
any Stock Option Agreements and related Options for which this Agreement (and
the Option granted hereby) may be exchanged. Upon receipt by Issuer of evidence
reasonably satisfactory to it of the loss, theft, destruction or mutilation of
this Agreement, and (in the case of loss, theft or destruction) of reasonably
satisfactory indemnification, and upon surrender and cancellation of this
Agreement, if mutilated, Issuer will execute and deliver a new Agreement of like
tenor and date. Any such new Agreement executed and delivered shall constitute
an additional contractual obligation on the part of Issuer, whether or not the
Agreement so lost, stolen, destroyed or mutilated shall at any time be
enforceable by anyone.

                  5. In addition to the adjustment in the number of shares of
Common Stock that are purchasable upon exercise of the Option pursuant to
Section 1 of this Agreement, the number of shares of Common Stock purchasable
upon the exercise of the Option and the Option Price shall be subject to
adjustment from time to time as provided in this Section 5. In the event of any
change in, or distributions in respect of, the Common Stock by reason of stock
dividends, split-ups, mergers, recapitalizations, combinations, subdivisions,
conversions, exchanges of shares, distributions on or in respect of the Common
Stock, or the like, the type and number of shares of Common Stock purchasable
upon exercise hereof and the Option Price shall be appropriately adjusted in
such manner as shall fully preserve the economic benefits provided hereunder and
proper provision shall be made in any agreement governing any such transaction
to provide for such proper adjustment and the full satisfaction of the Issuer's
obligations hereunder.

                  6. Upon the occurrence of a Subsequent Triggering Event that
occurs prior to an Exercise Termination Event, Issuer shall, at the request of
Grantee delivered within 90 days of such Subsequent Triggering Event (whether on
its own behalf or on behalf of any subsequent holder of this Option (or part
thereof) or any of the shares of Common Stock issued pursuant hereto), promptly
prepare, file and keep current a shelf registration statement under the 1933 Act
covering this Option and any shares issued and issuable pursuant to this Option
and shall use its reasonable best efforts to cause such registration statement
to become effective and remain current in order to permit the sale or other
disposition of this Option and any shares of Common

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Stock issued upon total or partial exercise of this Option ("Option Shares") in
accordance with any plan of disposition requested by Grantee. Issuer will use
its reasonable best efforts to cause such registration statement first to become
effective and then to remain effective for such period not in excess of 180 days
from the day such registration statement first becomes effective or such shorter
time as may be reasonably necessary to effect such sales or other dispositions.
Grantee shall have the right to demand two such registrations. The foregoing
notwithstanding, if, at the time of any request by Grantee for registration of
the Option or Option Shares as provided above, Issuer is in registration with
respect to an underwritten public offering of shares of Common Stock, and if in
the good faith judgment of the managing underwriter or managing underwriters,
or, if none, the sole underwriter or underwriters, of such offering the
inclusion of the Holder's Option or Option Shares would interfere with the
successful marketing of the shares of Common Stock offered by Issuer, the number
of Option Shares otherwise to be covered in the registration statement
contemplated hereby may be reduced; and provided, however, that after any such
required reduction the number of Option Shares to be included in such offering
for the account of the Holder shall constitute at least 25% of the total number
of shares to be sold by the Holder and Issuer in the aggregate; and provided
further, however, that if such reduction occurs, then the Issuer shall file a
registration statement for the balance as promptly as practical and no reduction
shall thereafter occur. Each such Holder shall provide all information
reasonably requested by Issuer for inclusion in any registration statement to be
filed hereunder. If requested by any such Holder in connection with such
registration, Issuer shall become a party to any underwriting agreement relating
to the sale of such shares, but only to the extent of obligating itself in
respect of representations, warranties, indemnities and other agreements
customarily included in secondary offering underwriting agreements for the
Issuer. Upon receiving any request under this Section 6 from any Holder, Issuer
agrees to send a copy thereof to any other person known to Issuer to be entitled
to registration rights under this Section 6, in each case by promptly mailing
the same, postage prepaid, to the address of record of the persons entitled to
receive such copies. Notwithstanding anything to the contrary contained herein,
in no event shall Issuer be obligated to effect more than two registrations
pursuant to this Section 6 by reason of the fact that there shall be more than
one Grantee as a result of any assignment or division of this Agreement.

                  7. (a) Immediately prior to the occurrence of a Repurchase
Event (as hereinafter defined), (i) following a request of the Holder, delivered
prior to an Exercise Termination Event, Issuer (or any successor thereto) shall
repurchase the Option from the Holder at a price (the "Option Repurchase Price")
equal to the amount by which (A) the Market/Offer Price (as hereinafter defined)
exceeds (B) the Option Price, multiplied by the number of shares for which this
Option may then be exercised and (ii) at the request of the owner of Option
Shares from time to time (the "Owner"), delivered within 90 days of such
occurrence (or such later period as provided in Section 10), Issuer shall
repurchase such number of the Option Shares from the Owner as the Owner shall
designate at a price (the "Option Share Repurchase Price") equal to the
Market/Offer Price multiplied by the number of Option Shares so designated. The
term "Market/Offer Price" shall mean the highest of (w) the price per share of
Common Stock at which a tender offer or exchange offer therefor has been made,
(x) the price per share of Common Stock to be paid by any third party pursuant
to an agreement with Issuer, (y) the highest closing price for shares of Common
Stock within the six-month period immediately preceding the date the Holder
gives notice of the required repurchase of this Option or the Owner gives notice
of the required repurchase of Option Shares, as the case may be, or (z) in the
event of a sale of all or a substantial portion of Issuer's assets, the sum of
the price paid in such sale for such assets and

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the current market value of the remaining assets of Issuer as determined by a
nationally recognized investment banking firm selected by the Holder or the
Owner, as the case may be, and reasonably acceptable to the Issuer, divided by
the number of shares of Common Stock of Issuer outstanding at the time of such
sale. In determining the Market/Offer Price, the value of consideration other
than cash shall be determined by a nationally recognized investment banking firm
selected by the Holder or Owner, as the case may be, and reasonably acceptable
to the Issuer.

                  (b) The Holder and the Owner, as the case may be, may exercise
its right to require Issuer to repurchase the Option and any Option Shares
pursuant to this Section 7 by surrendering for such purpose to Issuer, at its
principal office, a copy of this Agreement or certificates for Option Shares, as
applicable, accompanied by a written notice or notices stating that the Holder
or the Owner, as the case may be, elects to require Issuer to repurchase this
Option and/or the Option Shares in accordance with the provisions of this
Section 7. Within the latter to occur of (i) five business days after the
surrender of the Option and/or certificates representing Option Shares and the
receipt of such notice or notices relating thereto and (ii) the time that is
immediately prior to the occurrence of a Repurchase Event, Issuer shall deliver
or cause to be delivered to the Holder the Option Repurchase Price and/or to the
Owner the Option Share Repurchase Price therefor or the portion thereof, if any,
that Issuer is not then prohibited under applicable law and regulation from so
delivering.

                  (c) To the extent that Issuer is prohibited under applicable
law or regulation from repurchasing the Option and/or the Option Shares in full,
Issuer shall immediately so notify the Holder and/or the Owner and thereafter
deliver or cause to be delivered, from time to time, to the Holder and/or the
Owner, as appropriate, the portion of the Option Repurchase Price and the Option
Share Repurchase Price, respectively, that it is no longer prohibited from
delivering, within five business days after the date on which Issuer is no
longer so prohibited; provided, however, that if Issuer at any time after
delivery of a notice of repurchase pursuant to paragraph (b) of this Section 7
is prohibited under applicable law or regulation from delivering to the Holder
and/or the Owner, as appropriate, the Option Repurchase Price and the Option
Share Repurchase Price, respectively, in full (and Issuer hereby undertakes to
use its best efforts to obtain all required regulatory and legal approvals and
to file any required notices, in each case as promptly as practicable in order
to accomplish such repurchase), the Holder or Owner may revoke its notice of
repurchase of the Option or the Option Shares either in whole or to the extent
of the prohibition, whereupon, in the latter case, Issuer shall promptly (i)
deliver to the Holder and/or the Owner, as appropriate, that portion of the
Option Repurchase Price or the Option Share Repurchase Price that Issuer is not
prohibited from delivering; and (ii) deliver, as appropriate, either (A) to the
Holder, a new Stock Option Agreement evidencing the right of the Holder to
purchase that number of shares of Common Stock obtained by multiplying the
number of shares of Common Stock for which the surrendered Stock Option
Agreement was exercisable at the time of delivery of the notice of repurchase by
a fraction, the numerator of which is the Option Repurchase Price less the
portion thereof theretofore delivered to the Holder and the denominator of which
is the Option Repurchase Price, or (B) to the Owner, a certificate for the
Option Shares it is then so prohibited from repurchasing.

                  (d) For purposes of this Section 7, a "Repurchase Event" shall
be deemed to have occurred (i) upon the consummation of any merger,
consolidation or similar transaction involving Issuer or any purchase, lease or
other acquisition of all or a substantial portion of the as-

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sets of Issuer, other than any such transaction which would not constitute an
Acquisition Transaction pursuant to the provisos to Section 2(b)(i) or (ii) upon
the acquisition by any person of beneficial ownership of 50% or more of the then
outstanding shares of Common Stock, provided that no such event shall constitute
a Repurchase Event unless a Subsequent Triggering Event shall have occurred
prior to an Exercise Termination Event. The parties hereto agree that Issuer's
obligations to repurchase the Option or Option Shares under this Section 7 shall
not terminate upon the occurrence of an Exercise Termination Event unless no
Subsequent Triggering Event shall have occurred prior to the occurrence of an
Exercise Termination Event.

                  8. (a) In the event that prior to an Exercise Termination
Event, Issuer shall enter into an agreement (i) to consolidate with or merge
into any person, other than Grantee or any Grantee Subsidiary, and shall not be
the continuing or surviving corporation of such consolidation or merger, (ii) to
permit any person, other than Grantee or any Grantee Subsidiary, to merge into
Issuer and Issuer shall be the continuing or surviving corporation, but, in
connection with such merger, the then outstanding shares of Common Stock shall
be changed into or exchanged for stock or other securities of any other person
or cash or any other property or the then outstanding shares of Common Stock
shall after such merger represent less than 50% of the outstanding voting shares
and voting share equivalents of the merged company, or (iii) to sell or
otherwise transfer all or substantially all of its assets to any person, other
than Grantee or any Grantee Subsidiary, then, and in each such case, the
agreement governing such transaction shall make proper provision so that the
Option shall, upon the consummation of any such transaction and upon the terms
and conditions set forth herein, be converted into, or exchanged for, an option
(the "Substitute Option"), at the election of the Holder, of either (A) the
Acquiring Corporation (as hereinafter defined) or (B) any person that controls
the Acquiring Corporation.

                  (b) The following terms have the meanings indicated: (i)
"Acquiring Corporation" shall mean (A) the continuing or surviving corporation
of a consolidation or merger with Issuer (if other than Issuer), (B) Issuer in a
merger in which Issuer is the continuing or surviving person, and (C) the
transferee of all or substantially all of Issuer's assets; (ii) "Substitute
Common Stock" shall mean the common stock issued by the issuer of the Substitute
Option upon exercise of the Substitute Option; (iii) "Assigned Value" shall mean
the Market/Offer Price, as defined in Section 7; and (iv) "Average Price" shall
mean the average closing price of a share of the Substitute Common Stock for the
one year immediately preceding the consolidation, merger or sale in question,
but in no event higher than the closing price of the shares of Substitute Common
Stock on the day preceding such consolidation, merger or sale; provided that if
Issuer is the issuer of the Substitute Option, the Average Price shall be
computed with respect to a share of common stock issued by the person merging
into Issuer or by any company that controls or is controlled by such person, as
the Holder may elect.

                  (c) The Substitute Option shall have the same terms as the
Option, provided, that if the terms of the Substitute Option cannot, for legal
reasons, be the same as the Option, such terms shall be as similar as possible
and in no event less advantageous to the Holder. The issuer of the Substitute
Option shall also enter into an agreement with the then Holder or Holders of the
Substitute Option in substantially the same form as this Agreement, which shall
be applicable to the Substitute Option.


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                  (d) The Substitute Option shall be exercisable for such number
of shares of Substitute Common Stock as is equal to the Assigned Value
multiplied by the number of shares of Common Stock for which the Option is then
exercisable, divided by the Average Price. The exercise price of the Substitute
Option per share of Substitute Common Stock shall then be equal to the Option
Price multiplied by a fraction, the numerator of which shall be the number of
shares of Common Stock for which the Option is then exercisable and the
denominator of which shall be the number of shares of Substitute Common Stock
for which the Substitute Option is exercisable.

                  (e) In no event, pursuant to any of the foregoing paragraphs,
shall the Substitute Option be exercisable for more than 19.9% of the shares of
Substitute Common Stock outstanding prior to exercise of the Substitute Option.
In the event that the Substitute Option would be exercisable for more than 19.9%
of the shares of Substitute Common Stock outstanding prior to exercise but for
this clause (e), the issuer of the Substitute Option (the "Substitute Option
Issuer") shall make a cash payment to Holder equal to the excess of (i) the
value of the Substitute Option without giving effect to the limitation in this
clause (e) over (ii) the value of the Substitute Option after giving effect to
the limitation in this clause (e). This difference in value shall be determined
by a nationally recognized investment banking firm selected by the Holder or the
Owner, as the case may be, and reasonably acceptable to the Acquiring
Corporation.

                  (f) Issuer shall not enter into any transaction described in
Section 8(a) unless the Acquiring Corporation and any person that controls the
Acquiring Corporation assume in writing all the obligations of Issuer hereunder.

                  9. (a) At the request of the holder of the Substitute Option
(the "Substitute Option Holder"), the Substitute Option Issuer shall repurchase
the Substitute Option from the Substitute Option Holder at a price (the
"Substitute Option Repurchase Price") equal to the amount by which (i) the
Highest Closing Price (as hereinafter defined) exceeds (ii) the exercise price
of the Substitute Option, multiplied by the number of shares of Substitute
Common Stock for which the Substitute Option may then be exercised, and at the
request of the owner (the "Substitute Share Owner") of shares of Substitute
Common Stock (the "Substitute Shares"), the Substitute Option Issuer shall
repurchase the Substitute Shares at a price (the "Substitute Share Repurchase
Price") equal to the Highest Closing Price multiplied by the number of
Substitute Shares so designated. The term "Highest Closing Price" shall mean the
highest closing price for shares of Substitute Common Stock within the six-month
period immediately preceding the date the Substitute Option Holder gives notice
of the required repurchase of the Substitute Option or the Substitute Share
Owner gives notice of the required repurchase of the Substitute Shares, as
applicable.

                  (b) The Substitute Option Holder and the Substitute Share
Owner, as the case may be, may exercise its respective right to require the
Substitute Option Issuer to repurchase the Substitute Option and the Substitute
Shares pursuant to this Section 9 by surrendering for such purpose to the
Substitute Option Issuer, at its principal office, the agreement for such
Substitute Option (or, in the absence of such an agreement, a copy of this
Agreement) and certificates for Substitute Shares accompanied by a written
notice or notices stating that the Substitute Option Holder or the Substitute
Share Owner, as the case may be, elects to require the Substitute Option Issuer
to repurchase the Substitute Option and/or the Substitute Shares in accordance
with the

                                      A-9
   10
provisions of this Section 9. As promptly as practicable, and in any event
within five business days after the surrender of the Substitute Option and/or
certificates representing Substitute Shares and the receipt of such notice or
notices relating thereto, the Substitute Option Issuer shall deliver or cause to
be delivered to the Substitute Option Holder the Substitute Option Repurchase
Price and/or to the Substitute Share Owner the Substitute Share Repurchase Price
therefor or, in either case, the portion thereof which the Substitute Option
Issuer is not then prohibited under applicable law and regulation from so
delivering.

                  (c) To the extent that the Substitute Option Issuer is
prohibited under applicable law or regulation from repurchasing the Substitute
Option and/or the Substitute Shares in part or in full, the Substitute Option
Issuer following a request for repurchase pursuant to this Section 9 shall
immediately so notify the Substitute Option Holder and/or the Substitute Share
Owner and thereafter deliver or cause to be delivered, from time to time, to the
Substitute Option Holder and/or the Substitute Share Owner, as appropriate, the
portion of the Substitute Share Repurchase Price, respectively, which it is no
longer prohibited from delivering, within five business days after the date on
which the Substitute Option Issuer is no longer so prohibited; provided,
however, that if the Substitute Option Issuer is at any time after delivery of a
notice of repurchase pursuant to Section 9(b) prohibited under applicable law or
regulation from delivering to the Substitute Option Holder and/or the Substitute
Share Owner, as appropriate, the Substitute Option Repurchase Price and the
Substitute Share Repurchase Price, respectively, in full (and the Substitute
Option Issuer shall use its best efforts to obtain all required regulatory and
legal approvals, in each case as promptly as practicable, in order to accomplish
such repurchase), the Substitute Option Holder or Substitute Share Owner may
revoke its notice of repurchase of the Substitute Option or the Substitute
Shares either in whole or to the extent of the prohibition, whereupon, in the
latter case, the Substitute Option Issuer shall promptly (i) deliver to the
Substitute Option Holder or Substitute Share Owner, as appropriate, that portion
of the Substitute Option Repurchase Price or the Substitute Share Repurchase
Price that the Substitute Option Issuer is not prohibited from delivering; and
(ii) deliver, as appropriate, either (A) to the Substitute Option Holder, a new
Substitute Option evidencing the right of the Substitute Option Holder to
purchase that number of shares of the Substitute Common Stock obtained by
multiplying the number of shares of the Substitute Common Stock for which the
surrendered Substitute Option was exercisable at the time of delivery of the
notice of repurchase by a fraction, the numerator of which is the Substitute
Option Repurchase Price less the portion thereof theretofore delivered to the
Substitute Option Holder and the denominator of which is the Substitute Option
Repurchase Price, or (B) to the Substitute Share Owner, a certificate for the
Substitute Common Shares it is then so prohibited from repurchasing.

                  10. The 90-day or six-month periods for exercise of certain
rights under Sections 2, 6, 7, 13 and 15 shall be extended: (a) to the extent
necessary to obtain all regulatory approvals for the exercise of such rights,
and for the expiration of all statutory waiting periods; (b) to the extent
necessary to avoid liability under Section 16(b) of the 1934 Act by reason of
such exercise and (c) during any period in which Grantee is precluded from
exercising such rights due to an injunction or other legal restriction, plus in
each case such additional period as is reasonably necessary for the exercise of
such rights promptly following the obtaining of such approvals or the expiration
of such periods.


                                      A-10
   11
                  11. Issuer hereby represents and warrants to Grantee as
follows:

                  (a) Issuer has full corporate power and authority to execute
and deliver this Agreement and to consummate the transactions contemplated
hereby. The execution and delivery of this Agreement and the consummation of the
transactions contemplated hereby have been duly and validly authorized by the
board of directors of Issuer and no other corporate proceedings on the part of
Issuer are necessary to authorize this Agreement or to consummate the
transactions so contemplated. This Agreement has been duly and validly executed
and delivered by Issuer.

                  (b) Issuer has taken all necessary corporate action to
authorize and reserve and to permit it to issue, and at all times from the date
hereof through the termination of this Agreement in accordance with its terms
will have reserved for issuance upon the exercise of the Option, that number of
shares of Common Stock equal to the maximum number of shares of Common Stock at
any time and from time to time issuable hereunder, and all such shares, upon
issuance pursuant hereto, will be duly authorized, validly issued, fully paid,
nonassessable, and will be delivered free and clear of all claims, liens,
encumbrance and security interests and not subject to any preemptive rights.

                  12. Grantee hereby represents and warrants to Issuer that:

                  (a) Grantee has all requisite corporate power and authority to
enter into this Agreement and, subject to any approvals or consents referred to
herein, to consummate the transactions contemplated hereby. The execution and
delivery of this Agreement and the consummation of the transactions contemplated
hereby have been duly authorized by all necessary corporate action on the part
of Grantee. This Agreement has been duly executed and delivered by Grantee.

                  (b) The Option is not being, and any shares of Common Stock or
other securities acquired by Grantee upon exercise of the Option will not be,
acquired with a view to the public distribution thereof and will not be
transferred or otherwise disposed of except in a transaction registered or
exempt from registration under the 1933 Act.

                  13. Neither of the parties hereto may assign any of its rights
or obligations under this Option Agreement or the Option created hereunder to
any other person, without the express written consent of the other party, except
that in the event a Subsequent Triggering Event shall have occurred prior to an
Exercise Termination Event, Grantee, subject to the express provisions hereof,
may assign in whole or in part its rights and obligations hereunder within 90
days following such Subsequent Triggering Event (or such later period as
provided in Section 10); provided, however, that until the date 15 days
following the date on which the Federal Reserve Board approves an application by
Grantee under the BHCA to acquire the shares of Common Stock subject to the
Option, Grantee may not assign its rights under the Option except in (a) a
widely dispersed public distribution, (b) a private placement in which no one
party acquires the right to purchase in excess of 2% of the voting shares of
Issuer, (c) an assignment to a single party (e.g., a broker or investment
banker) for the purpose of conducting a widely dispersed public distribution on
Grantee's behalf, or (d) any other manner approved by the Federal Reserve Board.


                                      A-11
   12
                  14. Each of Grantee and Issuer will use its best efforts to
make all filings with, and to obtain consents of, all third parties and
governmental authorities necessary to the consummation of the transactions
contemplated by this Agreement, including without limitation making application
to list the shares of Common Stock issuable hereunder on the New York Stock
Exchange upon official notice of issuance and applying to the Federal Reserve
Board under the BHCA for approval to acquire the shares issuable hereunder, but
Grantee shall not be obligated to apply to state banking authorities for
approval to acquire the shares of Common Stock issuable hereunder until such
time, if ever, as it deems appropriate to do so.

                  15. (a) Grantee in its sole discretion may, at any time during
which Issuer would be required to repurchase the Option or any Option Shares
pursuant to Section 7, surrender the Option (together with any Option Shares
issued to and then owned by the Holder) to Issuer in exchange for a cash payment
equal to the Surrender Price (as hereinafter defined); provided, however, the
Grantee may not exercise its rights pursuant to this Section 15 if Issuer has
previously repurchased the Option (or any portion thereof) or any Option Shares
pursuant to Section 7. The "Surrender Price" shall be equal to (i) $420 million,
plus (ii) if applicable, the aggregate purchase price previously paid pursuant
hereto by Grantee with respect to any Option Shares, minus (iii) if applicable,
the excess of (A) the net cash, if any, received by Grantee pursuant to the
arm's-length sale of Option Shares (or any other securities into which such
Option Shares were converted or exchanged) to any party not affiliated with
Grantee, over (B) the purchase price paid by Grantee with respect to such Option
Shares.

                  (b) Grantee may exercise its right to surrender the Option and
any Option Shares pursuant to this Section 15 by surrendering for such purpose
to Issuer, at its principal office, a copy of this Agreement, together with
certificates for Option Shares, if any, accompanied by a written notice stating
(i) that Grantee elects to surrender the Option and Option Shares, if any, in
accordance with the provisions of this Section 15 and (ii) the Surrender Price.
Within two business days after the surrender of the Option and the Option
Shares, if applicable, Issuer shall deliver or cause to be delivered to Grantee
the Surrender Price.

                  (c) To the extent that the Issuer is prohibited under
applicable law or regulation from paying the Surrender Price to Grantee in full,
Issuer shall immediately so notify Grantee and thereafter deliver, or cause to
be delivered, from time to time, to Grantee, that portion of the Surrender Price
that Issuer is not or no longer prohibited from paying, within two business days
after the date on which Issuer is no longer so prohibited; provided, however,
that if Issuer at any time after delivery of a notice of surrender pursuant to
Section 15(b) is prohibited under applicable law or regulation from paying to
Grantee the Surrender Price in full, (i) Issuer shall (A) use its best efforts
to obtain all required regulatory and legal approvals and to file any required
notices as promptly as practicable in order to make such payments, (B) within
two business days of the submission or receipt of any documents relating to any
such regulatory and legal approvals, provide Grantee with copies of the same,
and (C) keep Grantee advised of both the status of any such request for
regulatory and legal approvals and any discussions with any relevant regulatory
or other third party reasonably related to the same, and (ii) Grantee may revoke
such notice or surrender by delivery of a notice of revocation to Issuer and,
upon delivery of such notice of revocation, the Exercise Termination Event shall
be extended to a date six months from the date on which the Exercise Termination
Event would have occurred if not for the provisions

                                      A-12
   13
of this Section 15(c) (during which period Grantee may exercise any of its
rights hereunder, including any and all rights pursuant to this Section 15).

                  (d) Grantee shall have rights substantially identical to those
set forth in Sections 15(a), 15(b) and 15(c) with respect to the Substitute
Option and the Substitute Option Issuer during any period in which the
Substitute Option Issuer would be required to repurchase the Substitute Option
pursuant to Section 9.

                  16. (a) Notwithstanding any other provision herein, in no
event shall Grantee's Total Profit (as defined in Section 16(c)) exceed $630
million (the "Maximum Profit"), and, if the Total Profit would otherwise exceed
such amount, Grantee, at its sole election, shall either (i) reduce the number
of shares subject to the Option (and any Substitution Option), (ii) deliver to
Issuer, or Substitute Issuer, as the case may be, for cancellation shares of
Common Stock or Substitute Common Stock, as the case may be, previously
purchased by Grantee valued at fair market value at the time of delivery, (iii)
pay cash to Issuer, or Substitute Issuer, as the case may be, (iv) reduce the
amount of the Option Repurchase Price or Substitute Option Repurchase Price, or
(v) undertake any combination of the foregoing, so that Grantee's actually
realized Total Profit shall not exceed the Maximum Profit after taking into
account the foregoing actions.

                  (b) Notwithstanding any other provision of this Agreement, the
Option may not be exercised for a number of shares as would, as of the date of
exercise, result in a Notional Total Profit (as defined in Section 16(d)) of
more than the Maximum Profit and, if exercise of the Option would otherwise
result in the Notional Total Profit exceeding such amount, Grantee, in its
discretion, may take any of the actions specified in Section 16(a) so that the
Notional Total Profit shall not restrict any subsequent exercise of the Option
which at such time complies with this sentence.

                  (c) For purposes of this Agreement, the term "Total Profit"
shall mean the aggregate amount (before taxes) of the following: (i) the excess
of (A) the net cash amounts or fair market value of any property received by
Grantee pursuant to the sale of Option Shares (or any other securities into
which such Option Shares are converted or exchanged) to any unaffiliated party,
other than any amount received by Grantee upon the repurchase of Option Shares
by Issuer pursuant to Section 7, after payment of application brokerage or sales
commissions and discounts, over (B) Grantee's aggregate purchase price for such
Option Shares (or other securities), plus (ii) all amounts received by Grantee
upon the repurchase of the Option by Issuer pursuant to Section 7, plus (iii)
all equivalent amounts with respect to the Substitute Option and any amounts
paid pursuant to Section 9.

                  (d) For purposes of this Agreement, the term "Notional Total
Profit" with respect to any number of shares as to which Grantee may propose to
exercise the Option shall be the Total Profit, determined as of the date of such
proposed exercise assuming that the Option were exercised on such date for such
number of shares, and assuming that such shares, together with all other Option
Shares held by Grantee and its affiliates as of such date, were sold for cash at
the closing market price for the Common Stock as of the close of business on the
preceding trading day (less customary brokerage commissions). For purposes of
this Section 16, transac-

                                      A-13
   14
tions by a wholly-owned Subsidiary transferee of Grantee in respect of the
Option Shares transferred to it shall be treated as if made by Grantee.

                  17. The parties hereto acknowledge that damages would be an
inadequate remedy for a breach of this Agreement by either party hereto and that
the obligations of the parties hereto shall be enforceable by either party
hereto through injunctive or other equitable relief.

                  18. If any term, provision, covenant or restriction contained
in this Agreement is held by a court or a federal or state regulatory agency of
competent jurisdiction to be invalid, void or unenforceable, the remainder of
the terms, provisions and covenants and restrictions contained in this Agreement
shall remain in full force and effect, and shall in no way be affected, impaired
or invalidated. If for any reason such court or regulatory agency determines
that the Holder is not permitted to acquire, or Issuer or Substitute Option
Issuer, as the case may be, is not permitted to repurchase pursuant to Section 7
or Section 9, as the case may be, the full number of shares of Common Stock
provided in Section 1(a) (as adjusted pursuant to Section 1(b) or 5), or Issuer
or Substitute Option Issuer is not permitted to pay the full Surrender Price, it
is the express intention of Issuer (which shall be binding on the Substitute
Option Issuer) to allow the Holder to acquire or to require Issuer or the
Substitute Option Issuer, as the case may be, to repurchase such lesser number
of shares, or to pay such portion of the Surrender Price, as may be permissible,
without any amendment or modification hereof.

                  19. All notices, requests, claims, demands and other
communications hereunder shall be deemed to have been duly given when delivered
in person, by cable, telegram, telecopy or telex, or by registered or certified
mail (postage prepaid, return receipt requested) at the respective addresses of
the parties set forth in the Merger Agreement.

                  20. This Agreement shall be governed by and construed in
accordance with the laws of the State of Delaware, regardless of the laws that
might otherwise govern under applicable principles of conflicts of laws thereof
(except to the extent that mandatory provisions of federal law apply).

                  21. This Agreement may be executed in two or more
counterparts, each of which shall be deemed to be an original, but all of which
shall constitute one and the same agreement.

                  22. Except as otherwise expressly provided herein, each of the
parties hereto shall bear and pay all costs and expenses incurred by it or on
its behalf in connection with the transactions contemplated hereunder, including
fees and expenses of its own financial consultants, investment bankers,
accountants and counsel.

                  23. Except as otherwise expressly provided herein or in the
Merger Agreement, this Agreement contains the entire agreement between the
parties with respect to the transactions contemplated hereunder and supersedes
all prior arrangements or understandings with respect thereof, written or oral.
The terms and conditions of this Agreement shall inure to the benefit of and be
binding upon the parties hereto and their respective successors and permitted
assigns. Nothing in this Agreement, expressed or implied, is intended to confer
upon any party, other than the parties hereto, and their respective successors
except as assigns, any rights, reme-

                                      A-14
   15
dies, obligations or liabilities under or by reason of this Agreement, except as
expressly provided herein.

                  24. Capitalized terms used in this Agreement and not defined
herein shall have the meanings assigned thereto in the Merger Agreement.

                                      A-15
   16
                  IN WITNESS WHEREOF, each of the parties has caused this
Agreement to be executed on its behalf by its officers thereunto duly
authorized, all as of the date first above written.

                                        U.S. BANCORP



                                        By:  /s/ John F. Grundhofer
                                             John F. Grundhofer
                                             Chairman, President and Chief
                                             Executive Officer



                                        FIRSTAR CORPORATION



                                        By:   /s/ Jerry A. Grundhofer
                                             Jerry A. Grundhofer
                                             President and Chief
                                             Executive Officer



                           [U.S. Bancorp Stock Option]


                                      A-16