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                                                                   EXHIBIT 10(A)

                                  Summary of

                             BANK ONE CORPORATION
                            STOCK PERFORMANCE PLAN
                           (As of February 20, 2001)


1.   General

     The purpose of Bank One's Stock Performance Plan (the "Plan") is to provide
incentives and rewards for employees of Bank One and its subsidiaries to:

     .    support the execution of Bank One's business and human resource
          strategies and the achievement of its goals; and

     .    associate the interests of employees with those of Bank One's
          stockholders.

     The Plan is not subject to the provisions of the Employee Retirement Income
Security Act of 1974, as amended.

2.   Participants

     Any employee of Bank One or one of its subsidiaries selected by the Board's
Organization, Compensation and Nominating Committee (the "Committee") is
eligible to receive an award under and thereby participate in the Plan. In
addition, the Committee may select former employees who have a consulting
arrangement with Bank One or a Bank One subsidiary to receive an award under the
Plan if the Committee determines such persons have significant responsibility
for Bank One's success and future growth and profitability. For purposes of the
Plan, a "subsidiary" is any corporation or other entity, whether domestic or
foreign, in which Bank One has or obtains, directly or indirectly, a proprietary
interest of at least 50% by reason of stock ownership or otherwise.

     In 2001, all of the approximately 80,000 employees of Bank One and its
subsidiaries (including directors of Bank One who are employees) are eligible to
participate in the Plan.

3.   Administration of the Plan

     Except as otherwise determined by the Board, the Committee will administer
the Plan. The Board, or the Committee to the extent determined by the Board,
shall determine periodically which employees shall participate in the Plan and,
except as otherwise required by law or the Plan, the grant terms of awards under
the Plan.  Such grant terms shall include:
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     .    vesting schedules
     .    price
     .    length of relevant performance, restriction or option period
     .    dividend rights
     .    post-retirement and termination rights
     .    payment alternatives such as cash, stock or other means of payment
          consistent with the Plan's purposes
     .    such other terms and conditions the Board or the Committee deems
          appropriate

     The Committee is authorized to interpret the Plan provisions and the award
summaries given to participants (each, an "Award Summary") and to make final and
binding determinations pursuant to any Plan provision or award.

     The Committee may designate persons other than its members to carry out its
responsibilities under such conditions or limitations as it may set, other than
its authority with regard to awards granted to employees who are officers or
directors of Bank One for purposes of Section 16 of the Securities Exchange Act
of 1934, as amended (the "Exchange Act").

     The Committee will determine the disposition of an award in the event of a
participant's retirement, disability, death or other termination of employment.
The Committee has the authority at any time to cancel awards for reasonable
cause and to provide for the conditions and circumstances under which awards
shall be forfeited.

4.   Shares Authorized

     The Plan provides that in any year the total number of shares of Bank One
Common Stock, $0.01 par value per share, (the "Common Stock") as to which awards
may be granted may not exceed 2% of Bank One's outstanding shares of Common
Stock as reported in Bank One's Annual Report on Form 10-K for the previous
year, subject to the adjustments described below; however, no more than
16,200,000 shares in the aggregate for all years may be awarded pursuant to
incentive stock options.  Also available for award in any year in addition to
the 2% limit:

     .    any unused portion of the 2% limit for any previous year;
     .    any shares of Common Stock previously subject to awards which are
          cancelled, forfeited, terminated, surrendered, paid in cash or expire
          unexercised;
     .    the excess amount of variable awards which become fixed at less than
          their maximum limitations; and
     .    shares of Common Stock used to pay the purchase price or any
          withholding taxes associated therewith upon the exercise of an option,
          to the extent such shares result in the grant of a restorative option;

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provided, however, that the total number of shares of Common Stock available for
awards under the Plan in any year may not exceed 5% of the outstanding Common
Stock as reported in Bank One's Annual Report on Form 10-K for the year ending
immediately prior to such year.  The grant of a performance or restricted share
or unit award is deemed to be a grant equal to the maximum number of shares
which may be issued under the award.  Where the value of the award is variable
on the date it is granted, the value is deemed to be the maximum limitation of
the award. Awards payable solely in cash will not reduce the number of shares
available for award under the Plan.

     A participant may receive multiple grants of stock-based awards.  The terms
and provisions of a type of award need not be the same for all recipients of
such an award.  The Plan provides that during any five-year period, a
participant may not be granted (i) stock options and stock appreciation rights
("SARs") with respect to more than 10,000,000 shares of Common Stock (except
that a stock option issued in tandem with an SAR shall be counted as one stock
option for purposes of this maximum) or (ii) more than 5,000,000 performance
shares (based on the maximum number of shares of Common Stock that may be
earned).

     The Common Stock which may be issued pursuant to the Plan will be shares of
authorized but unissued Common Stock and shares of Common Stock held as treasury
stock.  A participant will pay the aggregate purchase price for Common Stock
purchased under the Plan to Bank One and, in connection with such purchases,
will not owe any fees, commissions or other charges to Bank One or any of its
affiliates or any person having a material relationship with Bank One or any of
its affiliates.

5.   Grants and Awards

     As the Board or Committee may determine, the following types of awards may
be granted under the Plan on a stand-alone or combination basis:

  .  Stock Option
  .  Incentive Stock Option
  .  Stock Appreciation Right
  .  Restricted and Performance Shares
  .  Restricted and Performance Share Units
  .  Dividend or Equivalent Rights
  .  Stock Award
  .  Other Stock-Based Awards

     No Common Stock will be issued pursuant to any award unless Bank One
receives consideration at least equal to the par value thereof in the form of
cash, services rendered or property.

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     The Committee, in its sole discretion, may from time to time establish
performance criteria with respect to an award.  Such criteria may be absolute or
relative to other companies and may be particular to a line of business,
subsidiary or other unit.

     Each award will be evidenced by an Award Summary which will describe the
award's terms and conditions.

     For purposes of the Plan, "Fair Market Value" means the closing price of
the Common Stock on the New York Stock Exchange Composite Transactions Tape on
the business day immediately preceding the grant date; provided, however, that
the Committee may modify the definition of Fair Market Value with respect to any
particular award.

     Awards granted to executive officers and any other participants subject to
certain rules of the Securities and Exchange Commission (the "Commission") may
include other requirements or restrictions, including with respect to vesting
periods and/or holding periods.

6.   Amendment

     The Board may at any time amend, suspend or discontinue the Plan and alter
or amend any awards granted thereunder to the extent permitted by law and the
terms of the Plan. There is no set termination date for the Plan.

7.   Adjustments and Change of Control

     The Committee may adjust the number of shares of Common Stock available for
issuance, the number of shares covered by any outstanding award and the price
per share thereof in the event there is a change in Bank One's capital structure
as a result of any stock dividend or split, recapitalization, merger,
consolidation or spin-off, or other similar event.

     The Committee will determine, and the relevant Award Summary will state, to
what extent, if any, an award's terms and conditions will be modified in the
event of a Change of Control, as defined by the Committee from time to time, of
Bank One.

8.   Resale of Shares

     The Plan does not impose restrictions on the resale of Common Stock
acquired by participants pursuant to the Plan.

9.   Tax Withholding

     Bank One has the right to require the participant to pay in cash or to
deduct from the participant's salary or severance benefits or other amounts paid
to the participant any sums required by federal, state or local tax law to be
withheld.  If acceptable to the Committee, in its

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sole discretion, and pursuant to rules established for such purpose, the
participant may elect to exchange shares of Common Stock held by the
participant, to simultaneously exercise and sell option shares or to tender
option shares in order to satisfy the participant's withholding tax obligations
with respect to such exercise.

     If appropriate, FICA taxes will be withheld from the paycheck following
option exercise. Bank One reserves the right to require cash payment by the
participant in satisfaction of FICA tax liability.

10.  Assignment

     Except to the extent permitted by Rule 16b-3 under the Exchange Act, or
Section 422 of the Code, and as otherwise provided in the Award Summary, (i) no
award shall be assignable or transferable, except by will or by the laws of
descent and distribution and (ii) during a participant's lifetime the award
shall be exercisable only by such participant or such participant's guardian,
legal representative or permitted transferee.  In the event that any award is
transferred as described in the preceding sentence, the permitted transferee
shall be deemed the award recipient under the Plan.  Stock options, incentive
stock options and SARs shall be exercisable during the transferee's lifetime
only by the award recipient or by the award recipient's guardian, legal
representative or similar person.

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