EXHIBIT 10.28

UNIONBANCAL CORPORATION MANAGEMENT STOCK PLAN  TERMS AND CONDITIONS APPLICABLE TO  NON-EMPLOYEE DIRECTOR STOCK UNIT AWARDS

The Executive Compensation and Benefits Committee (the "Committee") of the Board of Directors (the "Board") of UnionBanCal Corporation (the "Company"), pursuant
to its authority under the Year 2000 UnionBanCal Corporation Management Stock Plan (the "Plan"), has approved the following Terms and Conditions Applicable to Non-Employee Director Stock
Unit Awards (these "Terms and Conditions"), which shall apply to the award of Stock Units to Non-Employee Directors in lieu of certain fees pursuant to deferral elections under the Plan.
Capitalized terms used but not otherwise defined herein shall have the meanings attributed thereto in the Plan, the provisions of which are incorporated herein by reference.

1.Eligibility.    All Non-Employee Directors are eligible to elect
irrevocably to defer all or a portion of their Retainer Fees or Meeting Fees (as defined below), or both, and instead receive Stock Units pursuant to these Terms and Conditions and the Plan. An
eligible Director who executes a Non-Employee Director Stock Unit Award Agreement or who has previously deferred fees under the Plan and who continues to have an account balance greater
than zero will be considered a "Participant" for purposes of these Terms and Conditions and the Plan.

2.Deferral Election.



3.Stock Units; Stock Unit Accounts.



---





4.Vesting of Stock Units.    Stock Units credited to a Participant's Stock Unit
Account with respect to deferred Retainer Fees and/or Meeting Fees shall be fully vested at all times. Units representing dividend equivalents credited pursuant to Section 6 below shall also be
fully vested at all times.

5.Limitations on Rights Associated with Stock Units.    A Participant's Stock Unit
Account shall be a memorandum account on the books of the Company. The Stock Units credited to a Participant's Stock Unit Account shall be used solely as a device for the determination of the number
of shares of Common Stock to be distributed eventually to the Participant under the Plan pursuant to Section 7. The Stock Units shall not be treated as property or as a trust fund of any kind.
No Participant shall be entitled to any voting or other stockholder rights with respect to Stock Units granted or credited under the Plan. The number of Stock Units credited (and the Common Stock to
which the Participant is entitled upon distribution under the Plan) shall be subject to adjustment in accordance with Section 8 hereof and Section 3(b) of the Plan. The Stock Unit
Agreement and these Terms and Conditions shall create only a contractual obligation on the part of the Company as to such amounts and shall not be construed as creating a trust. The Plan, in and of
itself, has no assets. A Participant shall have only the rights of a general unsecured creditor of the Company with respect to amounts credited and rights no greater than the right to receive the
Common Stock (or equivalent value) as a general unsecured creditor.

6.Dividend Equivalent Credits to Stock Unit Account.    As of each date on which
dividends are paid with respect to the Common Stock, a Participant's Stock Unit Account shall be credited with additional Stock Units in an amount equal to (i) the amount of the dividends paid
on that number of shares of Common Stock equal to the aggregate number of Stock Units allocated to the Participant's Stock Unit Account as of that date divided by (ii) the Fair Market Value of
a share of Common Stock as of such date.

7.Distribution of Stock.



2

---





3

---





8.Adjustments in Case of Corporate Transactions.    If there should be any change in
the Company's Common Stock through merger, consolidation, reorganization, recapitalization, reincorporation, stock split, stock dividend (in excess of 2 percent) or other change in the
corporate structure of the Company, the Board and the Committee shall make appropriate adjustments in order to preserve but not to duplicate or otherwise increase the benefit to the Participant
(taking into account any dividend equivalents credited pursuant to Section 6), including adjustments in the number of Stock Units credited to a Participant's Stock Unit Account. Any adjustment
made pursuant to this Section 8 as a consequence of a change in the corporate structure of the Company shall not entitle the Participant to receive a number of shares of Common Stock of the
Company or shares of stock of any successor company greater than the number of shares the Participant would receive if, prior to such change, the Participant had actually held a number of shares of
Common Stock equal to the number of Stock Units then credited to his or her Stock Unit Account.

9.Company's Right to Withhold.    The Company shall satisfy any income tax
withholding obligation arising upon distribution of a Participant's Stock Unit Account by reducing the number of shares of Common Stock otherwise deliverable to the Participant. The appropriate number
of shares required to
satisfy any such tax withholding obligation in the case of Stock Units will be based on the Fair Market Value of a share of Common Stock on the business day prior to the date of distribution. If the
Company, for any reason, cannot satisfy the withholding obligation in accordance with the preceding sentence, the Participant shall pay or provide for payment in cash of the amount of any taxes which
the Company may be required to withhold with respect to the benefits hereunder.

10.Limitation on Eligible Directors.    Participation in the Plan shall not give any
person the right to continue to serve as a member of the Board or any rights or interests other than as herein provided.

11.Beneficiaries.



12.Mandatory Arbitration.    Any dispute arising out of or relating to a Stock Unit
Agreement, including its meaning or interpretation, shall be resolved solely by arbitration before an arbitrator selected in accordance with the rules of the American Arbitration Association. The
location for the arbitration shall be in San Francisco, Los Angeles, San Diego, Portland, Seattle, and New York City, as selected by Company in good faith. Judgment on the award rendered may be
entered in any court having jurisdiction. The party the arbitrator determines is the prevailing party shall be entitled to have the other part pay the expenses of the prevailing party, and in this
regard the arbitrator shall have the power to award recovery to such prevailing party of all costs and fees (including attorneys fees and a reasonable allocation for the costs of the Company's
in-house counsel), administrative fees, arbitrator's

4

---



fees
and court costs, all as determined by the arbitrator. Absent such award of the arbitrator, each party shall pay an equal share of the arbitrator's fees. All statutes of limitation which would
otherwise be applicable shall apply to any arbitration proceeding under this paragraph. The provisions of this paragraph are intended to be exclusive for all purposes and applicable to any and all
disputes arising out of or relating to a Stock Unit Agreement. The arbitrator who hears and decides any dispute shall have jurisdiction and authority only to award compensatory damages to make whole a
person or entity sustaining foreseeable economic damages, and, shall not have jurisdiction and authority to make any other award of any type, including without limitation, punitive damages,
unforeseeable economic damages, damages for pain, suffering or emotional distress, or any other kind or form of damages. The remedy, if any, awarded by the arbitrator shall be the sole and exclusive
remedy for any dispute which is subject to arbitration under this paragraph.

13.Other Provisions.



5

---





6

---



QuickLinks