<PAGE>

                                                                   EXHIBIT 10.34


                           PROMISSORY NOTE (SECURED)


$20,000,000.00                                  Chicago, Illinois March 10, 2000
                                                               Due March 9, 2001

     FOR VALUE RECEIVED, the undersigned (jointly and severally if more than
one) ("Borrower"), promises to pay to the order of AMERICAN NATIONAL BANK AND
TRUST COMPANY OF CHICAGO ("Bank"), at its principal place of business in
Chicago, Illinois or such other place as Bank may designate from time to time
hereafter, the principal sum of Twenty Million Dollars, or such lesser principal
sum as may then be owed by Borrower to Bank hereunder, which sum shall be due
and payable on March 9, 2001.

     Borrower's obligations and liabilities to Bank under this Note, and all
other obligations and liabilities of Borrower to Bank (including without
limitation all debts, claims and indebtedness) whether primary, secondary,
direct, contingent, fixed or otherwise, including those evidenced in rate
hedging agreements designed to protect the Borrower from the fluctuation of
interest rates, heretofore, now and/or from time to time hereafter owing, due or
payable, however evidenced, created, incurred, acquired or owing and however
arising, whether under this Note, any agreement, instrument or document
heretofore, now or from time to time hereafter executed and delivered to Bank by
or on behalf of Borrower, or by oral agreement or operation of law or otherwise
shall be defined and referred to herein as "Borrower's Liabilities."

     The unpaid principal balance of Borrower's Liabilities due hereunder shall
bear interest from the date hereof until paid, computed (i) at a daily rate
equal to the daily rate equivalent of 175 basis points in excess of the London
Interbank Offered Rate announced by Bank per the London Interbank Offered Rate
Borrowing Agreement with even date herewith; or (ii) at a daily rate equal to
the daily rate equivalent of the rate of interest announced or published
publicly from time to time by Bank as its prime or base rate of interest
computed on the basis of a 360-day year and actual days elapsed (the "Base
Rate"); provided, however, that in the event that any of Borrower's Liabilities
        --------  -------
are not paid when due, the unpaid amount of Borrower's Liabilities shall bear
interest after the due date until paid at a rate equal to the sum of the rate
that would otherwise be in effect plus 3%.

     If the rate of interest to be charged by Bank to Borrower hereunder is that
specified in clause (ii) above, such rate shall fluctuate hereafter from time to
time concurrently with, and in an amount equal to, each increase or decrease in
the Base Rate, whichever is applicable.

     Accrued interest shall be payable by Borrower to Bank on June 30, 2000,
September 30, 2000, December 31, 2000, and at maturity, or as billed by Bank to
Borrower, at Bank's principal place of business, or at such other place as Bank
may designate from time to time hereafter. After maturity, accrued interest on
all of Borrower's Liabilities shall be payable on demand.

     Borrower shall pay to Bank within twenty (20) days from the date of the
Bank's invoice therefor, a Revolving Loan Commitment Fee (the "Revolving Loan
Commitment Fee") at the rate of three sixteenths of one percent (0.1875%) per
annum on the average daily unused portion of the Note.  The Revolving Loan
Commitment Fee shall be payable quarterly in arrears commencing on June 30, 2000
(which payment shall include the period commencing on the date hereof),
September 30, 2000, December 31, 2000 and on the due date of this Note.

     Borrower warrants and represents to Bank that Borrower shall use the
proceeds represented by this Note solely for proper business purposes and
consistently with all applicable laws and statutes.
<PAGE>

Borrower further warrants that borrowings under this Note will be used solely
for the purpose of purchasing loans from Colorado Business Bank, N.A.

     To secure the prompt payment to Bank of Borrower's Liabilities and the
prompt, full and faithful performance by Borrower of all of the provisions to be
kept, observed or performed by Borrower under this Note and/or any other
agreement, instrument or document heretofore, now and/or from time to time
hereafter delivered by or on behalf of Borrower to Bank, Borrower grants to Bank
a security interest in and to the following property: (a) all of Borrower's now
existing and/or owned and hereafter arising or acquired monies, reserves,
deposits, deposit accounts and interest or dividends thereon, securities, cash,
cash equivalents and other property now or at any time or times hereafter in the
possession or under the control of Bank or its bailee for any purpose; (b) 100%
of the common stock (__20,000____ shares) of Colorado Business Bank, N.A., per
the Stock Pledge and Security Agreement dated March 10, 2000, and any additions,
amendments, replacements, or substitutions made thereto; and (c) all
substitutions, renewals, improvements, accessions or additions thereto,
replacements, offspring, rents, issues, profits, returns, products and proceeds
thereof, including without limitation proceeds of insurance policies insuring
the foregoing collateral (all of the foregoing property is referred to herein
individually and collectively as "Collateral").

     Regardless of the adequacy of the Collateral, any deposits or other sums at
any time credited by or payable or due from Bank to Borrower, or any monies,
cash, cash equivalents, securities, instruments, documents or other assets of
Borrower in the possession or control of Bank or its bailee for any purpose, may
be reduced to cash and applied by Bank to or setoff by Bank against Borrower's
Liabilities.

     Borrower agrees to deliver to Bank immediately upon Bank's demand, such
additional collateral as Bank may request from time to time should the value of
the Collateral (in Bank's sole and exclusive opinion) decline, deteriorate,
depreciate or become impaired, or should Bank deem itself insecure for any
reason whatsoever, including without limitation a change in the financial
condition of Borrower or any party liable with respect to Borrower's
Liabilities, and does hereby grant to Bank a continuing security interest in
such other collateral, which shall be deemed to be a part of the Collateral.
Borrower shall execute and deliver to Bank, at any time upon Bank's demand, all
agreements, instruments, documents and other written matter that Bank may
request, in form and substance acceptable to Bank, to perfect and maintain
perfected Bank's security interest in the Collateral or any additional
collateral.  Borrower agrees that a carbon, photographic or photostatic copy, or
other reproduction, of this Note or of any financing statement, shall be
sufficient as a financing statement.

     Bank may take, and Borrower hereby waives notice of, any action from time
to time that Bank may deem necessary or appropriate to maintain or protect the
Collateral, and Bank's security interest therein, and in particular Bank may at
any time (i) transfer the whole or any part of the Collateral into the name of
the Bank or its nominee, (ii) collect any amounts due on Collateral directly
from persons obligated thereon, (iii) take control of any proceeds and products
of Collateral, and/or (iv) sue or make any compromise or settlement with respect
to any Collateral.  Borrower hereby releases Bank from any and all causes of
action or claims which Borrower may now or hereafter have for any asserted loss
or damage to Borrower claimed to be caused by or arising from: (a) Bank's taking
any action permitted by this paragraph; (b) any failure of Bank to protect,
enforce or collect in whole or in part any of the Collateral; and/or (c) any
other act or omission to act on the part of Bank, its officers, agents or
employees, except for willful misconduct.

     The occurrence of any one of the following events shall constitute a
default by the Borrower ("Event of Default") under this Note: (a) if Borrower
fails to pay any of Borrower's Liabilities when due and payable or declared due
and payable (whether by scheduled maturity, required payment, acceleration,
demand or otherwise); (b) if Borrower or any guarantor of any of Borrower's
Liabilities fails or neglects

                                       2
<PAGE>

to perform, keep or observe any term, provision, condition, covenant, warranty
or representation contained in this Note; (c) occurrence of a default or event
of default under any agreement, instrument or document heretofore, now or at any
time hereafter delivered by or on behalf of Borrower to Bank; (d) occurrence of
a default or an event of default under any agreement, instrument or document
heretofore, now or at any time hereafter delivered to Bank by any guarantor of
Borrower's Liabilities or by any person or entity which has granted to Bank a
security interest or lien in and to some or all of such person's or entity's
real or personal property to secure the payment of Borrower's Liabilities; (e)
if the Collateral or any other of Borrower's assets are attached, seized,
subjected to a writ, or are levied upon or become subject to any lien or come
within the possession of any receiver, trustee, custodian or assignee for the
benefit of creditors; (f) if a notice of lien, levy or assessment is filed of
record or given to Borrower with respect to all or any of Borrower's assets by
any federal, state or local department or agency; (g) if Borrower or any
guarantor of Borrower's Liabilities becomes insolvent or generally fails to pay
or admits in writing its inability to pay debts as they become due, if a
petition under Title 11 of the United States Code or any similar law or
regulation is filed by or against Borrower or any such guarantor, if Borrower or
any such guarantor shall make an assignment for the benefit of creditors, if any
case or proceeding is filed by or against Borrower or any such guarantor for its
dissolution or liquidation, or if Borrower or any such guarantor is enjoined,
restrained or in any way prevented by court order from conducting all or any
material part of its business affairs; (h) the death or incompetency of Borrower
or any guarantor of Borrower's Liabilities, or the appointment of a conservator
for all or any portion of Borrower's assets or the Collateral; (i) the
revocation, termination or cancellation of any guaranty of Borrower's
Liabilities without written consent of Bank; (j) if a contribution failure
occurs with respect to any pension plan maintained by Borrower or any
corporation, trade or business that is, along with Borrower, a member of a
controlled group of corporations or a controlled group of trades or businesses
(as described in Sections 414(b) and (c) of the Internal Revenue Code of 1986 or
Section 4001 of the Employee Retirement Income Security Act of 1974, as amended,
"ERISA") sufficient to give rise to a lien under Section 302(f) of ERISA; (k) if
Borrower or any guarantor of Borrower's Liabilities is in default in the payment
of any obligations, indebtedness or other liabilities to any third party and
such default is declared and is not cured within the time, if any, specified
therefor in any agreement governing the same; (l) if any material statement,
report or certificate made or delivered by Borrower, any of Borrower's partners,
officers, employees or agents or any guarantor of Borrower's Liabilities is not
true and correct; or (m) if Bank is reasonably insecure.

     Upon the occurrence of an Event of Default, at Bank's option, without
notice by Bank to or demand by Bank of Borrower: (i) all of Borrower's
Liabilities shall be immediately due and payable; (ii) Bank may exercise any one
or more of the rights and remedies accruing to a secured party under the Uniform
Commercial Code of the relevant jurisdiction and any other applicable law upon
default by a debtor; (iii) Bank may enter, with or without process of law and
without breach of the peace, any premises where the Collateral is or may be
located, and may seize or remove the Collateral from said premises and/or remain
upon said premises and use the same for the purpose of collecting, preparing and
disposing of the Collateral; and/or (iv) Bank may sell or otherwise dispose of
the Collateral at public or private sale for cash or credit, provided, however,
that Borrower shall be credited with the net proceeds of any such sale only when
the same are actually received by Bank.

     Upon an Event of Default, Borrower, immediately upon demand by Bank, shall
assemble the Collateral and make it available to Bank at a place or places to be
designated by Bank which is reasonably convenient to Bank and Borrower.

     All of Bank's rights and remedies under this Note are cumulative and non-
exclusive. The acceptance by Bank of any partial payment made hereunder after
the time when any of Borrower's Liabilities become due and payable will not
establish a custom or waive any rights of Bank to enforce prompt payment hereof.
Bank's failure to require strict performance by Borrower of any provision of
this Note shall not waive, affect or diminish any right of Bank thereafterto
demand strict compliance and

                                       3
<PAGE>

performance therewith. Any waiver of an Event of Default hereunder shall not
suspend, waive or affect any other Event of Default hereunder. Borrower and
every endorser waive presentment, demand and protest and notice of presentment,
protest, default, non-payment, maturity, release, compromise, settlement,
extension or renewal of this Note, and hereby ratify and confirm whatever Bank
may do in this regard. Borrower further waives any and all notice or demand to
which Borrower might be entitled with respect to this Note by virtue of any
applicable statute or law (to the extent permitted by law).

     Borrower agrees to pay, immediately upon demand by Bank, any and all costs,
fees and expenses (including reasonable attorneys' fees, costs and expenses)
incurred by Bank (i) in enforcing any of Bank's rights hereunder, and (ii) in
representing Bank in any litigation, contest, suit or dispute, or to commence,
defend or intervene or to take any action with respect to any litigation,
contest, suit or dispute (whether instituted by Bank, Borrower or any other
person) in any way relating to this Note, Borrower's Liabilities or the
Collateral, and to the extent not paid the same shall become part of Borrower's
Liabilities.

     This Note shall be deemed to have been submitted by Borrower to Bank and to
have been made at Bank's principal place of business.  This Note shall be
governed and controlled by the internal laws of the State of Illinois and not
the law of conflicts.

     Advances under this Note may be made by Bank upon oral or written request
of any person authorized to make such requests on behalf of Borrower
("Authorized Person").  Borrower agrees that Bank may act on requests which Bank
in good faith believes to be made by an Authorized Person, regardless of whether
such requests are in fact made by an Authorized Person.  Any such advance shall
be conclusively presumed to have been made by Bank to or for the benefit of
Borrower.  Borrower does hereby irrevocably confirm, ratify and approve all such
advances by Bank and agrees to indemnify Bank against any and all losses and
expenses (including reasonable attorneys' fees) and shall hold Bank harmless
with respect thereto.


     TO INDUCE BANK TO ACCEPT THIS NOTE, BORROWER IRREVOCABLY AGREES THAT,
SUBJECT TO BANK'S SOLE AND ABSOLUTE ELECTION, ALL ACTIONS OR PROCEEDINGS IN ANY
WAY, MANNER OR RESPECT, ARISING OUT OF OR FROM OR RELATED TO THIS NOTE SHALL BE
LITIGATED IN COURTS HAVING SITUS WITHIN THE CITY OF CHICAGO, STATE OF ILLINOIS.
BORROWER HEREBY CONSENTS AND SUBMITS TO THE JURISDICTION OF ANY LOCAL, STATE OR
FEDERAL COURT LOCATED WITHIN SAID CITY AND STATE. BORROWER HEREBY WAIVES ANY
RIGHT IT MAY HAVE TO TRANSFER OR CHANGE THE VENUE OF ANY LITIGATION BROUGHT
AGAINST BORROWER BY BANK IN ACCORDANCE WITH THIS PARAGRAPH.


     BORROWER IRREVOCABLY WAIVES ANY RIGHT TO TRIAL BY JURY IN ANY ACTION, SUIT,
COUNTERCLAIM OR PROCEEDING (I) TO ENFORCE OR DEFEND ANY RIGHTS UNDER OR IN
CONNECTION WITH THIS NOTE OR ANY AMENDMENT, INSTRUMENT, DOCUMENT OR AGREEMENT
DELIVERED OR WHICH MAY IN THE FUTURE BE DELIVERED IN CONNECTION HEREWITH, OR
(II) ARISING FROM ANY DISPUTE OR CONTROVERSY IN CONNECTION WITH OR RELATED TO
THIS NOTE OR ANY SUCH AMENDMENT, INSTRUMENT, DOCUMENT OR AGREEMENT, AND AGREES
THAT ANY SUCH ACTION, SUIT, COUNTERCLAIM OR PROCEEDING SHALL BE TRIED BEFORE A
COURT AND NOT BEFORE A JURY.

                                       4
<PAGE>

821 17th Street                   COLORADO BUSINESS BANKSHARES, INC.
Denver, Colorado 80202            -----------------------------------
TIN # 84-0826324                  Borrower
      ----------


                                     /s/ Jonathan C. Lorenz
                                  ---------------------------------------------
                                  By:      Jonathan C. Lorenz
                                     ------------------------------------------
                                  Its:        President
                                      -----------------------------------------

                                       5
<PAGE>

                      STOCK PLEDGE AND SECURITY AGREEMENT
                      -----------------------------------


  This Stock Pledge and Security Agreement (this "Agreement") is dated as of the
10th day of March, 2000; by and between COLORADO BUSINESS BANKSHARES, INC.
(hereinafter referred to as "Pledgor") and AMERICAN NATIONAL BANK AND TRUST
COMPANY OF CHICAGO, a national banking association (hereinafter referred to as
"Bank").

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

     WHEREAS, in order to secure the payment and performance of Pledgor's
obligations and liabilities to Bank, Pledgor has agreed to pledge and grant a
lien and security interest to Bank in and to the securities listed and described
in Section 1 hereof and Exhibit "A" attached hereto and all additions thereto
from time to time:

     WHEREAS, this Agreement has been executed and delivered by Pledgor to Bank
pursuant to the Note of even date in the amount of twenty million dollars
($20,000,000), referred to herein as the "Note";

     NOW, THEREFORE, in consideration of the foregoing, the covenants and
conditions herein contained herein, and the mutual agreements of the parties
hereto, Pledgor and Bank hereby agree as follows:

1. To secure the payment and performance of all Pledgor's obligations and
   liabilities to Bank, whether absolute or contingent, due or to become due,
   direct or indirect, whether now existing or hereafter and howsoever arising,
   and howsoever evidenced, whether under the Notes, any extension or renewal
   thereof, or otherwise (hereinafter collectively referred to as the
   "Liabilities"), Pledgor hereby pledges and assigns to Bank and grants unto
   Bank a security interest in:

   a.  the securities described in Exhibit "A" attached hereto, with stock power
       attached thereto, all duly endorsed in blank, herewith delivered to Bank
       and all additions thereto from time to time deposited by Pledgor with
       Bank;

   b.  any and all other securities deposited with Bank from time to time in
       accordance with the provisions of paragraph 3 hereof;

   c.  any and all other additional securities to which Pledgor (without
       additional consideration) now is, or hereafter may be, entitled by virtue
       of its ownership of any of the foregoing securities as the result of any
       corporate reorganization, merger or consolidation, stock split, stock
       dividend or other wise; and

   d.  any and all dividends, distributions and other amounts to which Bank is
       entitled pursuant to the provisions of paragraph 4 hereof:

(a) through (d) above are hereinafter collectively referred to as the
"Collateral."

                                       6
<PAGE>

2.   Representations and Warranties
     ------------------------------

         Pledgor warrants, represents and covenants to the Bank that as of the
date of the execution of this Agreement, and continuing so long as any of
Borrower's Liabilities (as that term is defined in the Note) remain outstanding,
and (even if there shall be no Borrower's Liabilities outstanding) so long as
the Note remains in effect:

     a.  Each of Pledgor and Pledgor's subsidiaries: (i) is a corporation or a
         national bank, respectively, duly organized and validly existing and in
         good standing under the laws of the jurisdiction of its organization;
         (ii) is duly qualified as a foreign corporation and in good standing in
         all states in which it is doing business except where the failure to so
         qualify would not have a material adverse effect on Pledgor or any of
         Pledgor's subsidiaries, or their respective businesses; and (iii) has
         all requisite power and authority, corporate or otherwise, to own,
         operate and lease its properties and to carry on its business as now
         being conducted.

     b.  Pledgor has full right, power and authority to enter into, execute,
         deliver and perform this Stock Pledge and Security Agreement; Each
         advance under the Note and the execution and delivery of the Note are
         within the corporate and other powers of Pledgor. The Note and the
         other agreements of even date have been duly authorized, executed and
         delivered by Pledgor and the Note is the legal, valid and binding
         obligation of Pledgor, enforceable against such Persons in accordance
         with their respective terms, subject to applicable bankruptcy,
         insolvency, reorganization, moratorium or similar laws affecting the
         rights of creditors generally, and general principles of equity.

     c.  There are no actions or proceedings which are pending or threatened
         against Pledgor or Colorado Business Bank, N.A. ("CBB") which might
         materially affect the Collateral or Pledgor's ability to repay
         Pledgor's Liabilities;

     d.  No governmental orders, permissions, consents, approvals or
         authorizations are required to be obtained and no registrations or
         declarations are required to be filed in connection with, or
         contemplation of, the execution and delivery of the Note, which have
         not been obtained or filed.

     e.  None of Pledgor, or any of Pledgor's subsidiaries or any of their
         respective officers or directors is now operating under any currently
         effective written restrictions agreed to by Pledgor or any of Pledgor's
         subsidiaries, or agreements, memoranda, or written commitments by
         Pledgor or any of Pledgor's subsidiaries (other than restrictions of
         general application) imposed or required by any Governmental Authority
         nor are any such restrictions threatened or agreements, memoranda or
         commitments being sought by any Governmental Authority. "Governmental
         Authority" shall mean any nation or government, any state or other
         political subdivision thereof any entity exercising executive,
         legislative, judicial or regulatory or administrative functions of or
         pertaining to government, including without limitation the Federal
         Reserve Board ("FRB"), the Comptroller of the Currency (the "OCC"), the
         Federal Deposit Insurance Corporation (the "FDIC"), or the Colorado
         Department of Banking.

     f.  The execution, delivery and/or performance by Pledgor of this Stock
         Pledge and Security Agreement does not and shall not, by the lapse of
         time, the giving of notice or otherwise, constitute a violation of any
         applicable law or of any order, judgment or decree to which Pledgor, or
         any of its property is subject, or a breach of any provision contained
         in Pledgor's Articles of Incorporation or By-laws, or contained in any
         agreement, instrument or document to which Pledgor is now or hereafter
         may become a party or by which Pledgor or any of its property is or may
         become bound;

                                       7
<PAGE>

     g.  as to the Collateral deposited with Bank (i) Pledgor is the legal and
         beneficial owner thereof, (ii) the same is validly issued, fully paid
         and non-assessable and is registered in Pledgor's name, (iii) the stock
         transfer forms attached to the certificates representing such
         Collateral have been duly executed and delivered by Pledgor to Bank,
         and (iv) none of such Collateral is subject to any security interest,
         pledge, lien or other encumbrance, or adverse claim of any kind
         whatsoever, except for the interest therein granted to Bank hereby; and

     h.  Pledgor shall at all times keep complete and accurate books and records
         and prepare financial statements and shall cause to be delivered to
         Bank on an annual basis or when there is a material change signed
         personal financial statements listing all assets, liabilities, and
         income of Pledgor; and any such other information which Bank may
         reasonably request.

     i.  Pledgor shall deliver to Lender:

               (i)    as soon as available, but in any event not more than 90
         days after the close of each Fiscal Year of Pledgor, consolidated
         audited financial statements for Pledgor, prepared in accordance with
         GAAP consistently applied throughout the periods reflected therein by
         independent certified public accountants reasonably acceptable to
         Lender, with such accountants' unqualified opinion with respect
         thereto;

               (ii)   as soon as available, but in no event later than forty-
         five (45) days after the end of each calendar quarter, a copy of: (1)
         the balance sheet, profit and loss statement, surplus statement and any
         supporting schedules for each of Pledgor prepared in accordance with
         GAAP consistently applied; and (2) the quarterly financial statements
         of Pledgor and CBB, including, but not limited to, all call reports,
         filed with any state or federal bank regulatory authority

               (iii)  to the extent permitted by law, promptly after the same
         are available, copies of: (A) each annual report, proxy or financial
         statement or other report or communication sent by Pledgor to the
         stockholders of Pledgor; (B) each registration statement which Pledgor
         may file with any Governmental Authority or with any securities
         exchange; (C) all annual, regular, periodic and special reports which
         Pledgor may file or be required to file with any Governmental Authority
         or with any securities exchange that relate to the overall financial
         condition or results of operations of Pledgor;

               (iv)   promptly after Bank shall request the same, such other
         information respecting the Pledgor or any of its subsidiaries, as the
         Bank may request.

     j.  Pledgor shall cause CBB to permit Bank through its employees,
         attorneys, accountants or other agents, to inspect any of the
         properties and the corporate and financial books and records of Pledgor
         and CBB at such times and as often as Lender may reasonably request.

3.   Stock Splits, Stock Dividends, Etc.
     -----------------------------------

     a.  In the event that Pledgor, by virtue of its ownership of the Collateral
         now is, or hereafter becomes, entitled (without additional
         consideration) to other or additional securities as the result of any
         corporate reorganization, merger or consolidation, stock split, stock
         dividend or otherwise, or acquires the securities of any other bank
         from time to time, Pledgor shall:

         (i)   cause the issuer thereof to deliver to Bank the certificates
               evidencing Pledgor's ownership thereof and hereby authorizes and
               empowers Bank to demand the same from such issuer, and agrees if

                                       8
<PAGE>

               such certificates are delivered to Pledgor, to take possession
               thereof in trust for Bank and forthwith deliver the same to Bank;

         (ii)  deliver to Bank a stock transfer form with respect to such
               securities, executed in blank by Pledgor and on which shall be
               endorsed the guarantee by a banking association acceptable to
               Bank, that the signature on such form is genuine;

         (iii) deliver to Bank a certificate, executed by Pledgor and dated the
               date of such pledge, as to the truth and correctness on such date
               of the warranties set forth in sub-paragraph (d) or paragraph 2
               hereof; and

         (iv)  deliver to Bank such other certificates, forms, and other
               instruments as Bank may request in connection with such pledge.

     b.  Pledgor agrees that such securities shall constitute a portion of the
         Collateral and be subject to this Stock Pledge and Security Agreement
         in the same manner and to the same extent as the securities hereby
         pledged to Bank on the date hereof.

4.   Voting Power, Dividends, Substitutions
     --------------------------------------

     Unless and until an Event of Default hereunder shall have occurred, Pledgor
shall be entitled to:

     a.  exercise all voting powers pertaining to the securities included in the
         Collateral for any purpose not inconsistent with, or in violation of,
         the provisions of this Stock Pledge and Security Agreement, in all
         corporate matters except (unless Bank consents thereto) those which, in
         Bank's sole discretion, may affect the value of the assets owned by the
         issuer of the securities comprising the Collateral or the value of the
         Collateral; and

     b.  collect and receive all cash dividends and distributions with respect
         to the securities included in the collateral paid out of the retained
         earnings or the current net profits of the issuer thereof. Bank shall
         be entitled to collect and receive all other dividends and
         distributions on such securities (whether in stock, cash or other
         property) received in exchange or substitution for or upon conversion
         of, such securities, and all amounts payable or distributable upon the
         liquidation, whether voluntary or involuntary, of any issuer thereof.
         Cash received by Bank pursuant to the provisions of this paragraph 4
         may be commingled by Bank with its other funds, and shall be
         noninterest bearing. Pledgor agrees that if it receives any of such
         dividends, distributions, securities and other amounts to which Bank is
         entitled, it shall take possession thereof in trust for Bank and
         forthwith deliver the same to Bank, and agrees that the same shall
         constitute a portion of the Collateral and be subject to this Stock
         Pledge and Security Agreement in the same manner and to the same extent
         as the securities pledged to Bank on the date hereof.

5.   Default and Remedies
     --------------------

     a.  The occurrence of any of the following shall constitute an Event of
         Default hereunder:

         (i)   any representation or warranty made by Pledgor to Bank hereunder,
               or in any certificate delivered to Bank pursuant hereto, or under
               any other agreement between Pledgor and Bank shall prove to have
               been false and misleading in any material respect as of the date
               on which the same was made, or Pledgor shall fail to observe or
               perform any term, provision, condition or covenant contained in
               this Stock Pledge and Security Agreement, the Notes, or any other

                                       9
<PAGE>

               agreement, instrument or document now or at anytime hereafter
               executed and delivered by Pledgor to Bank;

         (ii)  occurrence of a default or an event of default under the Notes,
               or any other agreement, instrument or document now or at any time
               hereafter executed and delivered to Bank by Pledgor; and

         (iii) the appointment of a receiver for Colorado Business Bank, N.A.
               ("CBB") or a cease and desist order is issued against CBB by the
               Federal Deposit Insurance Corporation ("FDIC"), the Office of the
               Comptroller of Currency ("OCC"), or the Colorado Commissioner of
               Banks or a memorandum of understanding is issued to CBB by the
               FDIC, the OCC, or the Colorado Commissioner of Banks or CBB
               becomes subject to any material regulatory sanction by the FDIC,
               the OCC, or the Colorado Commissioner of Banks.

     b.  If an Event of Default shall occur and be continuing, Bank may, at its
         option:

         (i)   cause the securities included in the Collateral to be registered
               in its name or in the name of its nominee;

         (ii)  exercise all voting powers pertaining to such securities and
               otherwise act with respect thereto as though Bank were the
               outright owner thereof (Pledgor hereby irrevocably constituting
               and appointing Bank its proxy and attorney-in-fact with full
               power of substitution so to do);

         (iii) receive all dividends and all other distributions of any kind
               whatsoever on all or any of such securities;

         (iv)  exercise any and all rights of collections, conversion or
               exchange, and any and all other rights, privileges, options or
               powers of Pledgor pertaining or relating to such securities
               (Pledgor hereby irrevocably constituting and appointing Bank its
               proxy and attorney in fact with full power of substitution so to
               do);

         (v)   sell, assign and deliver the whole, or from time to time any part
               of such securities at any broker's board or at any private sale
               or at public auction, with or without demand for performance,
               advertisement or notice of the time or place of sale or
               adjournment thereof or otherwise, and free from any right of
               redemption (all of which hereby are expressly waived) for cash,
               for credit or for other property, for immediate or future
               delivery, and for such price or prices and on such terms and Bank
               in its uncontrolled discretion may determine; and

         (vi)  exercise any other remedy specifically granted under this Stock
               Pledge and Security Agreement or now or hereafter existing in
               equity, at law, by virtue of statute or otherwise.

         c.    For purposes of this paragraph 5, an agreement to sell all or any
               part of such securities shall be treated as a sale thereof and
               Bank shall be free to carry out such sale pursuant to such
               agreement, and Pledgor shall not be entitled to the return of any
               of the same subject thereto, notwithstanding that after bank
               shall have entered into such an agreement, all Events of Default
               hereunder may have remedied.

         e.    At any sale made pursuant to subparagraph (b) of this paragraph
               5, Bank may bid for and purchase, free from any right or equity
               of redemption on the part of Pledgor (the same being hereby
               waived and released), and part of or all securities included in
               the Collateral that are offered for sale and may make payment on
               account thereof by using any claim then due and payable to Bank
               by Pledgor as a

                                       10
<PAGE>

               credit against the purchase price, and Bank may, upon compliance
               with the terms of sale, hold, retain and dispose of such
               securities without further accountability therefor.

         f.    Bank shall apply the proceeds of any sale of the whole or any
               part of such securities, and any other monies at the time held by
               Bank under the provisions of this Stock Pledge and Security
               Agreement, after deducting all costs and expenses of collection,
               sale and delivery (including, without limitation, reasonable
               attorneys' fees and other legal expenses) incurred by Bank in
               connection with such sale, towards the payment of the Pledgor's
               Liabilities. Bank shall remit any surplus to Pledgor.

         g.    Bank shall not have any duty to exercise any of the rights,
               privileges, options or powers, or to sell or otherwise realize
               upon any of such securities, as hereinbefore authorized, and Bank
               shall not be responsible for any failure to do so or delay in so
               doing.

         h.    Any sale of, or the grant of options to purchase, or any other
               realization upon, all or any portion of such securities under
               subparagraph (b) of this paragraph 5 shall operate to divest all
               right, title, interest, claim and demand, either at law or in
               equity, of Pledgor in and to such securities so sold, options or
               realized upon.

     6.  Bank's Obligations, Custodial Agreement
         ---------------------------------------

         a.    Bank shall have no duty to protect, preserve or enforce rights
               under any security included in the Collateral other than a duty
               of reasonable custodial care of any such security in its
               possession.

         b.    Pledgor understands and agrees that Bank may deposit such
               securities with a custodian and hereby agrees to pay reasonable
               fees of any such custodian in connection with its acting as
               custodian.

     7.  Termination Stock Pledge and Security Agreement
         -----------------------------------------------

         Upon the payment and performance in full of all of the Liabilities
         secured hereby, Bank shall cause to be transferred to Pledgor all of
         the stock pledged by Pledgor herein and any rights received by Bank
         pursuant hereto (less any portion of same sold, transferred or disposed
         of pursuant to, and under the circumstances specified in, paragraph 5
         hereof), and this Stock Pledge and Security Agreement shall thereupon
         be terminated.

     8.  Miscellaneous
         -------------

         a.    Bank may assign its rights under this Stock Pledge and Security
               Agreement, and may deliver the Collateral or any portion thereof
               to the assignee who shall thereupon to the extent provided in the
               instrument of assignment have all of the rights of Bank hereunder
               with respect to the Collateral and Bank shall, thereafter, be
               fully discharged from any responsibility with respect to the
               Collateral so delivered to such assignee. No such assignment,
               however, shall relieve such assignee of those duties and
               obligations of Bank specified hereunder.

         b.    Each and every right, remedy and power granted to Bank hereunder
               shall be cumulative, and in addition to any other right, remedy
               or power herein specifically granted now or hereafter existing in
               equity, at law, by virtue of statute or otherwise and may be
               exercised by Bank, from time to time, concurrently or
               independently and as often and in such order as Bank may deem
               expedient. Any failure or delay on the part of Bank in exercising
               any such right, remedy or

                                       11
<PAGE>

               power, or abandonment or discontinuance of steps to enforce the
               same, shall not operate as a waiver thereof or affect Bank's
               right thereafter to exercise the same, and any single or partial
               exercise of any such right, remedy or power shall not preclude
               any other, or further exercise thereof or the exercise of any
               other right, remedy or power.

         c.    Any modification or waiver of any provision of this Stock Pledge
               and Security Agreement, or any consent to any departure by Bank
               therefrom, shall not be effective in any event unless the same is
               in writing and signed by Bank and then such modification, waiver
               or consent shall be effective only in the specific instance and
               for the specific purpose given. Any notice to or demand on
               Pledgor in any event not specifically required of Bank hereunder
               shall not entitle Pledgor to any other or further notice or
               demand in the same, similar or other circumstance unless
               specifically required hereunder.

         d.    Pledgor agrees that at any time, and from time to time after the
               execution and delivery of this Stock Pledge and Security
               Agreement, it will, upon the request of Bank, execute and deliver
               such further documents and do such further acts and things as
               Bank may reasonably request in order to fully effect the purpose
               of this Stock Pledge and Security Agreement, and to subject to
               the security interest created hereby and property intended by the
               provisions hereof to be covered hereby.

         e.    Any notice, request, demand, consent, approval or other
               communication provided or permitted hereunder shall be in writing
               and be given by personal delivery or sent by United States first
               class mail, postage prepaid, addressed to the party for whom it
               is intended, at its address as follows:

               To Pledgor:  Colorado Business Bankshares, Inc.
                            Attention: Jonathan C. Lorenz
                            821 17th Street
                            Denver, Colorado 80202

               To Bank:     American National Bank and Trust Company of Chicago
                            Attention:  John L. Spalding
                            120 South LaSalle Street
                            Chicago, Illinois  60603-3400

               provided, however, that any party may change its address for
               purposes of receipt of any such communication by giving ten (10)
               days' written notice of such change to the other party in the
               manner above prescribed.

         f.    This Stock Pledge and Security Agreement shall be deemed to have
               been made under, and shall be governed by, the laws of the State
               of Illinois in all respects, including matters of construction,
               validity and performance.

         g.    If any provision of this Stock Pledge and Security Agreement is
               prohibited by, or is unlawful or unenforceable under any
               applicable law of any jurisdiction, such provision shall, as to
               such jurisdiction, be ineffective to the extent of such
               prohibition without invalidating the remaining provisions hereof;
               provided, however, that any such prohibition in any jurisdiction
               shall not invalidate such provision in any other jurisdiction;
               and provided, further, that where the provisions of any such
               applicable law may be waived, they are hereby waived by Pledgor
               to the full extent permitted by law to the end that this Stock
               Pledge and Security Agreement shall be deemed to be valid and
               binding in accordance with its terms.

         h.    This Stock Pledge and Security Agreement shall inure to the
               benefit of the successors and assigns of Bank and shall be
               binding upon the successors and assigns of Pledgor.

                                       12
<PAGE>

     IN WITNESS WHEREOF, this Agreement is effective as of the date first above
written.


                                           COLORADO BUSINESS BANKSHARES, INC.


                                           /s/ Jonathan C. Lorenz
                                           -------------------------------------

                                           By:    Jonathan C.Lorenz
                                              ----------------------------------
                                           Its:    President
                                               ---------------------------------



                                           AMERICAN NATIONAL BANK AND TRUST
                                            COMPANY OF CHICAGO


                                           /s/ John L. Spalding
                                           -------------------------------------

                                           By:    John L. Spalding
                                              ----------------------------------
                                           Its:    First Vice President
                                               ---------------------------------

                                       13
<PAGE>

               LONDON INTERBANK OFFERED RATE BORROWING AGREEMENT


     THIS LONDON INTERBANK OFFERED RATE ("LIBOR") BORROWING AGREEMENT (this
"Agreement"), dated as of the 10th  day of March, 2000 by and between AMERICAN
NATIONAL BANK AND TRUST COMPANY OF CHICAGO ("Bank"), a national banking
association with its principal place of business at 120 South LaSalle Street,
Chicago, Illinois  60603-3400, and COLORADO BUSINESS BANKSHARES, INC.
("Borrower"), with principal place of business at 821 17TH Street, Denver,
Colorado 80202, has reference to the following facts and circumstances:

     A. Borrower has requested and Bank has agreed to extend an interest rate
        option of 1.75% per annum in excess of the London Interbank Offered Rate
        ("LIBOR"); and

     B. Borrower has executed a Promissory Notes (Secured) with even date
        herewith in the amount of $20,000,000.00 in favor of Bank (the "Note")
        which reflects the LIBOR option.

     NOW, THEREFORE, in consideration of any loan, advance, extension of credit
and/or other financial accommodation at any time made by Bank to or for the
benefit of Borrower, and of the promises set forth herein, the parties hereto
agree as follows:

                           1.  DEFINITIONS AND TERMS
                               ---------------------

     1.1   The following words, terms and/or phrases shall have the meanings set
forth thereafter and such meanings shall be applicable to the singular and
plural form thereof; whenever the context so requires, the use of "it" in
reference to Borrower shall mean Borrower as identified at the beginning of this
Agreement:

           (a) "Amortization Date":  the dates specified in the Note when
                -----------------
               principal payments are due.

           (b) "Borrowing": any portion of Borrower's liabilities bearing
                ---------
               interest at LIBOR.

           (c) "Business Day": any day on which Bank is open for regular
                ------------
               business.

           (d) "Event of Default": the definition ascribed to this term in the
                ----------------
               Note.

           (e) "Interest Period": the period commencing on the date a LIBOR
                ---------------
               Loan is made and ending, as the Borrower may select for 90 days
               thereafter.

           (f) "LIBOR Loans": any principal portion of Borrower's liabilities
                -----------
               bearing interest at a rate based on LIBOR.

           (g) "LIBOR Margin":  1.750%
                ------------

           (h) "Maturity Date":  the date specified in the Notes upon which the
                -------------
               Borrower's liabilities are due and payable in full.

     1.2   Any terms or phrases not specifically defined in this Agreement shall
have the meanings ascribed to them in the Notes.

                                       14
<PAGE>

                         2.  MANNER OF LIBOR ELECTION
                             ------------------------

     2.1   Borrower may elect to cause all or a portion of the principal
outstanding on the Notes to bear interest at a daily rate equal to the daily
rate equivalent of 1.750% in excess of LIBOR, subject to the following
conditions:

           (a)  Not more than five (5) nor less than two (2) Business Days prior
                to the requested date of any LIBOR Borrowing, Borrower shall
                deliver to Bank an irrevocable written or telephonic notice
                setting forth the requested date and amount of such Borrowing
                and the requested Interest Period of such Borrowing;

           (b)  The LIBOR used in computing the interest rate applicable to such
                Borrowing shall be the LIBOR as quoted by Bank to Borrower as
                being in effect for the date of such Borrowing plus the LIBOR
                Margin, computed on the basis of a 360-day year and actual days
                elapsed, and shall be fixed for the requested period of such
                Borrowing;

           (c)  Such Borrowing may not be prepaid prior to the expiration of the
                requested Interest Period of such Borrowing and shall be repaid
                in full on the last day of the requested Interest Period of such
                Borrowing; and

           (d)  With respect to any Borrowing of LIBOR Loans, Borrower may not
                select an Interest Period that extends beyond the Maturity Date
                of the  Notes.

     2.2   In the event Borrower fails to give notice pursuant to Section 2.1(a)
of this Agreement regarding any maturing LIBOR Borrowing, Borrower shall be
deemed to have requested a Borrowing of Base or Prime Rate Loans (as defined in
the Notes) in the amount of  the maturing Borrowing.


                            3.  GENERAL PROVISIONS
                                ------------------

     3.1   Funding Indemnity.  In the event Bank shall incur any loss, cost or
           -----------------
expense (including, without limitation, any loss of profit, and any loss, cost
or expense incurred by reason of the liquidation or re-employment of deposits or
other funds acquired by such Bank to fund or maintain any LIBOR Loan or the
relending or reinvesting of such deposits or amounts paid or prepaid to such
Bank) as a result of:

           (a)  any payment or prepayment of a LIBOR Loan on a date other than
                the last day of its Interest Period,

           (b)  any failure by Borrower to borrow a LIBOR Loan on the date
                specified in a notice given pursuant to Section 2.1 hereof,

           (c)  any failure by Borrower to make any payment of principal on any
                LIBOR Loan when due (whether by acceleration or otherwise), or

           (d)  any acceleration of the maturity of a LIBOR Loan as a result of
                the occurrence of any Event of Default,

then, upon the demand of Bank, Borrower shall pay to Bank such amount as will
reimburse Bank for such loss, cost or expense.  If Bank makes such a claim for
compensation, it shall provide to Borrower a certificate executed by an officer
of Bank setting forth the amount of such loss, cost or expense in

                                       15
<PAGE>

reasonable detail (including an explanation of the basis for the computation of
such loss, cost or expense) and the amounts shown on such certificate if
reasonably calculated shall be conclusive.

     3.2   Availability of LIBOR Loans.  If Bank determines that maintenance of
           ---------------------------
its Loans would violate any applicable law, rule, regulation, or directive,
whether or not having the force of law, or if Bank determines that deposits of a
type and maturity appropriate to match fund LIBOR Loans are not available to it
then Bank shall forthwith give notice thereof to Borrower, whereupon, until Bank
notifies Borrower that the circumstances giving rise to such suspension no
longer exist, the obligations of the Bank to make LIBOR Loans shall be
suspended.

     IN WITNESS WHEREOF, this Agreement has been duly executed as of the day and
year specified at the beginning hereof.


                                            COLORADO BUSINESS BANKSHARES, INC.


                                                   /s/ Jonathan C. Lorenz
                                            ------------------------------------

                                            By:          Jonathan C. Lorenz
                                               ---------------------------------

                                            Its:          President
                                                --------------------------------



Accepted this 10th day of March, 2000, at Bank's principal place of business in
the City of Chicago, State of Illinois.


                                            AMERICAN NATIONAL BANK AND TRUST
                                             COMPANY OF CHICAGO



                                                  /s/ John L. Spalding
                                            ------------------------------------

                                            By:   John L. Spalding
                                               ---------------------------------

                                            Its:      First Vice President
                                                --------------------------------

                                       16