<PAGE>

                             STOCK OPTION AGREEMENT

                  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 as of March 1, 1997, between CB BANCORP,
INC., a Delaware  corporation ("Issuer"), and PINNACLE FINANCIAL SERVICES, INC.,
a Michigan corporation ("Grantee").

                                   WITNESSETH:

     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
(the "Agreement"); and

     WHEREAS, as a condition to Grantee's entering into the Merger Agreement and
in consideration therefor, 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 115,037
fully paid and nonassessable shares of Issuer's Common Stock, par value $ 0.01
per share ("Common Stock"), at a price of $28.50 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 9.9% 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 an event described in either clause
(i) or (ii), such number equals 9.9% 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.

<PAGE>

     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 defined) 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 subsection (e) of this
Section 2) within 60 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 (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 stockholders
     of Issuer approve or accept any Acquisition Transaction. For purposes of
     this Agreement, "Acquisition Transaction" shall mean (w) a merger or
     consolidation, or any similar transaction, involving Issuer or any
     Significant Subsidiary (as defined in Rule 1-02 of Regulation S-X
     promulgated by the Securities and Exchange Commission (the "SEC")) of
     Issuer, (x) a purchase, lease or other acquisition or assumption of all or
     a substantial portion of the assets or deposits of Issuer or any
     Significant Subsidiary of Issuer, (y) a purchase or other acquisition
     (including by way of merger, consolidation, share exchange or


                                       -2-

<PAGE>

     otherwise) of securities representing 10% or more of the voting power of
     Issuer, or (z) 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 of its Subsidiaries
     or involving only any two or more of such Subsidiaries, be deemed to be an
     Acquisition Transaction, provided that any such transaction is not entered
     into in violation of the terms of the Merger Agreement; and provided,
     further, that any transaction described in this sentence that is expressly
     permitted by the Merger Agreement shall not 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 stockholders of Issuer approve the transactions contemplated by
     the Merger Agreement;

          (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 (and other than any person who (a) as of the date hereof
     beneficially owns 10% or more of the outstanding shares of Common Stock and
     (b) would be eligible to use Schedule 13G but for the fact that such person
     owns 10% or more of the outstanding shares of Common Stock) shall have
     acquired beneficial ownership or the right to acquire beneficial ownership
     of 10% or 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 stockholders by
     public announcement or written communication that is or becomes the subject
     of public disclosure to engage in an Acquisition Transaction;

            (v)     After a bona fide proposal by public announcement or written
     communication is made by a third party to Issuer or its stockholders to
     engage in an Acquisition Transaction, Issuer shall have breached any
     covenant or obligation contained in the Merger Agreement and such breach
     (x) would entitle Grantee to terminate the Merger Agreement and (y) shall
     not have been cured prior to the Notice Date (as defined below); or


                                       -3-

<PAGE>

           (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, the Office of Thrift Supervision (the "OTS"), 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 in
     paragraph (i) of subsection (b) of this Section 2, except that the
     percentage referred to in clause (y) 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, the OTS 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 subsection (e) of this Section 2,
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.


                                       -4-

<PAGE>

          (g)  At such closing, simultaneously with the delivery of immediately
available funds as provided in subsection (f) of this Section 2, Issuer shall
deliver to the Holder a certificate or certificates 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
to 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 subsection (e) of this Section 2 and
the tender of the applicable purchase price in immediately available funds, the
Holder shall be deemed 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,


                                       -5-

<PAGE>

issue and delivery of stock certificates under this  Section 2 in the name of
the Holder or its assignee, transferee or designee.

          (j)  Notwithstanding anything to the contrary contained in this
Agreement, the Issuer shall not be obligated to issue shares of Common Stock
upon the exercise of the Option (i) in the absence of any required governmental
or regulatory approval or consent necessary for the Issuer to issue shares or
for the Grantee to exercise the Option, (ii) in the event and for so long as the
Grantee is in material breach of its representations, warranties, covenants or
obligations under the Merger Agreement (unless excused by reason of the material
breach of the Issuer of any of its representations, warranties, covenants or
obligations under the Merger Agreement), or (iii) so long as any injunction or
decree or ruling issued by a court of competent jurisdiction is in effect which
prohibits the sale or delivery of the Common Stock.

     3.   Issuer agrees:  (i) 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; (ii)
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;
(iii) promptly to take all action as may from time to time be required
(including (x) complying with all premerger notification, reporting and waiting
period requirements specified in 15 U.S.C. Section 18a and regulations
promulgated thereunder and (y) in the event, under the Bank Holding Company Act
of 1956, as amended (the "BHCA"), the Change in Bank Control Act of 1978, as
amended, the Home Owners' Loan Act, as amended, the Change in Savings and Loan
Control Act of 1978, as amended, or any other federal or state banking or
savings and loan law, prior approval of or notice to the Federal Reserve Board,
the OTS or to any other federal or 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, the OTS or such other federal or 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 (iv) 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


                                       -6-

<PAGE>

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 that would be
prohibited under the terms of the Merger Agreement, 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 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


                                       -7-

<PAGE>

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
defined below), (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 defined below) 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 (i) the price per share of Common Stock at which a tender
offer or exchange offer therefor has been made, (ii) the price per share of
Common Stock to be paid by any third party pursuant to an agreement with Issuer,
(iii) the highest closing price for shares of Common Stock within the
three-month period immediately preceding the date the Holder


                                       -8-

<PAGE>

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 (iv) 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 the current market value of the
remaining assets of Issuer as determined by a nationally recognized investment
banking firm mutually selected by the Holder or the Owner, as the case may be,
on the one hand, and the Issuer, on the other, 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 mutually selected
by the Holder or Owner, as the case may be, on the one hand, and the Issuer, on
the other.

          (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 (x) 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 (y) 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 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 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


                                       -9-

<PAGE>

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 assets of Issuer, other than
any such transaction which would not constitute an Acquisition Transaction
pursuant to the provisos to Section 2(b)(i) hereof 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 one of its Subsidiaries, and shall not be the continuing
or surviving corporation of such consolidation or merger, (ii) to permit any
person, other than Grantee or one of its Subsidiaries, 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 one of its
Subsidiaries, 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 (x) the Acquiring Corporation
(as hereinafter defined) or (y) any person that controls the Acquiring
Corporation.


                                      -10-

<PAGE>

          (b)  The following terms have the meanings indicated:

               (1)  "Acquiring Corporation" shall mean (i) the continuing or
     surviving corporation of a consolidation or merger with Issuer (if other
     than Issuer), (ii) Issuer in a merger in which Issuer is the continuing or
     surviving person, and (iii) the transferee of all or substantially all of
     Issuer's assets.

               (2)   "Substitute Common Stock" shall mean the common stock
     issued by the issuer of the Substitute Option upon exercise of the
     Substitute Option.

               (3)  "Assigned Value" shall mean the Market/Offer Price, as
     defined in Section 7.

               (4)  "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 which 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.

          (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 9.9% 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 9.9%
of the


                                      -11-

<PAGE>

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
subsection (a) of this Section 8 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 (x) 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 plus (y) Grantee's
reasonable out-of-pocket expenses (to the extent not previously reimbursed), 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 (x) the Highest Closing Price multiplied by the
number of Substitute Shares so designated plus (y) Grantee's reasonable Out-of-
Pocket Expenses (to the extent not previously reimbursed).  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 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


                                      -12-

<PAGE>

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 subsection (b) of this Section 9 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 receive all
required regulatory and legal approvals 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 period for exercise of certain rights under Sections 2, 6,
7 and 13 shall be extended:  (i) to the extent necessary to obtain all
regulatory approvals for the exercise of such rights, and for the expiration of
all statutory waiting


                                      -13-

<PAGE>

periods; and (ii) to the extent necessary to avoid liability under Section 16(b)
of the 1934 Act by reason of such exercise.

    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 Securities 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


                                      -14-

<PAGE>

(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 and/or
the OTS approves an application by Grantee if required under applicable law to
acquire the shares of Common Stock subject to the Option, Grantee may not assign
its rights under the Option except in (i) a widely dispersed public
distribution, (ii) a private placement in which no one party acquires the right
to purchase in excess of 2% of the voting shares of Issuer, (iii) 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 (iv)
any other manner approved by the Federal Reserve Board or the OTS, as
applicable.

    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 cause the
shares of Common Stock issuable hereunder to be approved for trading and
reporting on the Nasdaq National Market, upon official notice of issuance and
applying to the Federal Reserve Board and/or the OTS if required under
applicable law for approval to acquire the shares issuable hereunder.

    15.   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.

    16.   If any term, provision, covenant or restriction contained in the
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 is not permitted to
repurchase pursuant to Section 7, the full number of shares of Common Stock
provided in Section 1(a) hereof (as adjusted pursuant to Section 1(b) or 5
hereof), it is the express intention of Issuer to allow the Holder to acquire or
to require Issuer to repurchase such lesser number of shares as may be
permissible, without any amendment or modification hereof.

    17.   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.

    18.   This Agreement shall be governed by and construed in accordance with
the laws of the State of Delaware, regardless of


                                      -15-

<PAGE>

the laws that might otherwise govern under applicable principles of conflicts of
laws thereof.

    19.   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.

    20.   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.

    21.   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, remedies, obligations or liabilities under or by reason of
this Agreement, except as expressly provided herein.

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


                                      -16-

<PAGE>

     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.

                                        CB BANCORP, INC.


                                        By: _________________________________
                                             Joseph F. Heffernan
                                             Chairman, President and
                                              Chief Executive Officer


                                        PINNACLE FINANCIAL SERVICES, INC.


                                        By: _________________________________
                                             Richard L. Schanze
                                             Chairman and Chief Executive
                                              Officer


                                      -17-