S-4/A

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As filed with the Securities and Exchange Commission on May 14, 2003

Registration No. 333-105042

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

AMENDMENT NO. 1
TO
FORM S-4
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

UNIONBANCAL CORPORATION
(Exact name of Registrant as specified in its charter)

California
(State or other jurisdiction of
incorporation or organization) 6022
(Primary Standard Industrial
Classification Code Number) 94-1234979
(I.R.S. Employer
Identification No.)

400 California Street, San Francisco, California 94104-1302
(Address, including zip code, and telephone number, including area code, of Registrant's principal executive offices)

John H. McGuckin, Jr.
Executive Vice President and Secretary
UnionBanCal Corporation
400 California Street
San Francisco, California 94104-1302
(415) 765-2969
(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:
James M. Rockett, Esq. Venrice R. Palmer, Esq. Maureen A. Young, Esq. Bingham McCutchen LLP Three Embarcadero Center, 18th Floor San Francisco, California 94111 (415) 393-2000 Fax (415) 393-2286	Steven B. Stokdyk, Esq. Patrick S. Brown, Esq. Gabriel J. Steffens, Esq. Sullivan & Cromwell LLP 1888 Century Park East, Suite 2100 Los Angeles, California 90067-1724 (310) 712-6600 Fax: (310) 712-8800

Approximate date of commencement of proposed sale of the securities to the public:
As soon as practicable after this Registration Statement becomes effective.

        If the securities being registered on this Form are being offered in connection with the formation of a holding company and there is compliance with General Instruction G, check the following box.    o

        If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

        If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

SIGNATURES

        Pursuant to the requirements of the Securities Act, the registrant has duly caused this amendment to Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of San Francisco, State of California, on May 14, 2003.

UNIONBANCAL CORPORATION
By	/s/  JOHN H. MCGUCKIN, JR.* John H. McGuckin, Jr. Executive Vice President and Secretary

        Pursuant to the requirements of the Securities Act of 1933, this amendment to registration statement has been signed by the following persons in the capacities and on the dates indicated.

Name	Title	Date
/s/  NORIMICHI KANARI* Norimichi Kanari	President, Chief Executive Officer and Director (Principal Executive Officer)	May 14, 2003
/s/  DAVID I. MATSON* David I. Matson	Executive Vice President and Chief Financial Officer (Principal Financial Officer)	May 14, 2003
/s/  DAVID A. ANDERSON* David A. Anderson	Senior Vice President and Controller (Principal Accounting Officer)	May 14, 2003
/s/  L. DALE CRANDALL* L. Dale Crandall	Director	May 14, 2003
/s/  RICHARD D. FARMAN* Richard D. Farman	Director	May 14, 2003
/s/  MICHAEL J. GILLFILLAN* Michael J. Gillfillan	Director	May 14, 2003
/s/  KAORU HAYAMA* Kaoru Hayama	Director	May 14, 2003
/s/  MONICA C. LOZANO* Monica C. Lozano	Director	May 14, 2003
/s/  MARY S. METZ* Mary S. Metz	Director	May 14, 2003

II-4

/s/  RAYMOND E. MILES* Raymond E. Miles	Director	May 14, 2003
/s/  J. FERNANDO NIEBLA* J. Fernando Niebla	Director	May 14, 2003
/s/  CHARLES R. RINEHART* Charles R. Rinehart	Director	May 14, 2003
/s/  TAKAHARU SAEGUSA* Takaharu Saegusa	Director	May 14, 2003
/s/  ROBERT M. WALKER* Robert M. Walker	Director	May 14, 2003
/s/  *JOHN H. MCGUCKIN, JR. John H. McGuckin, Jr.	*Individually and as Attorney-in-Fact	May 14, 2003

II-5

Exhibit Index

2	Agreement and Plan of Merger, dated as of April 7, 2003, by and among Union Bank of California, N.A., UnionBanCal Corporation, Monterey Bay Bank and Monterey Bay Bancorp, Inc. (included in Part I as Annex A)
4	The text under the caption "II. Proposal to Change UnionBanCal Corporation's State of Incorporation From California to Delaware" and Annexes A, B and C in the registrant's Proxy Statement for the April 23, 2003 Annual Meeting of Shareholders, is incorporated herein by reference.
5	Opinion of Bingham McCutchen LLP as to validity of shares being registered
8	Opinion of Bingham McCutchen LLP as to certain tax matters*
23.1	Consent of Deloitte & Touche LLP regarding UnionBanCal Corporation
23.2	Consent of Deloitte & Touche LLP regarding Monterey Bay Bancorp, Inc.
23.3	Consent of Bingham McCutchen LLP (included in Exhibits 5 and 8)
23.4	Consent of Keefe, Bruyette & Woods, Inc.
24	Power of Attorney of directors and certain officers of the Registrant
99.1	Proxy card of Monterey Bay Bancorp, Inc.
99.2	Letter of transmittal/election form
99.3	Letter to brokers
99.4	Letter to brokers' customers
99.5	Letter to street name holders
99.6	Letter to registered stockholders*

*

filed herewith

II-6

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SIGNATURES
Exhibit Index

EX-8

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Exhibit 8

May 6, 2003

Union Bank of California, N.A.
400 California Street
San Francisco, California 94101

Merger of Monterey Bay Bank with Union Bank of California

Ladies and Gentlemen:

You have asked for our opinion as to certain federal income tax consequences of the merger (the "Bank Merger") of Monterey Bay Bank, a federal savings association ("Monterey Bay Bank") and Union Bank of California, N.A. ("UBOC"), a national banking association and wholly-owned subsidiary of UnionBanCal Corporation, a California corporation ("UnionBanCal"). The terms of the Bank Merger are set forth in the Agreement and Plan of Merger dated as of April 7, 2003, to which Monterey Bay Bank, Monterey Bay Bancorp, UBOC and UnionBanCal are parties (the "Agreement"). This opinion is delivered to you pursuant to Section 6.1(g) of the Agreement. Capitalized terms used in this letter without definition have the respective meanings given them in the Agreement.

The Agreement provides that Monterey Bay Bank will be merged with and into UBOC at the Effective Time pursuant to the applicable provisions of the National Bank Act and the rules and regulations promulgated by the Office of the Comptroller of the Currency and the Office of Thrift Supervision. In the Bank Merger, the issued and outstanding shares of Monterey Bay Bank stock (other than shares of Monterey Bay Bank stock for which dissenters' rights are perfected) will be converted into the right to receive from UnionBanCal the Parent Common Stock and/or cash described in the Agreement.

For purposes of rendering this opinion we have examined and relied upon (without any independent investigation or review) the truth, correctness and completeness at all relevant times of the statements, covenants, representations and warranties contained in the Agreement, in the Registration Statement of UnionBanCal on Form S-4 to which this opinion is an exhibit (the "Registration Statement"), and in the Officer's Certificates delivered to us by Monterey Bay Bank and UnionBanCal, and such other instruments and documents as we have deemed necessary.

Further, for purposes of rendering this opinion we have made the following assumptions (without any independent investigation or review):

1.

Original documents submitted to us (including signatures) are authentic, documents submitted to us as copies conform to the original documents and all such documents either have been or will be by the Effective Time duly and validly executed and delivered where such execution and delivery are prerequisites to effectiveness;

2.

All facts, statements, covenants, representations and warranties contained in any of the documents referred to herein or otherwise made to us in connection with the Bank Merger are true, correct and complete in all respects as of the date hereof and will be true, correct and complete in all respects as of the Effective Time, and no actions have been (or will be) taken which are inconsistent with such facts, statements, covenants, representations and warranties;

3.

The Bank Merger will be consummated in accordance with the terms of the Agreement and the Bank Merger will be effective under applicable laws; and

Union Bank of California, N.A.
May 6, 2003
Page 2

4.

The Bank Merger will be reported by Monterey Bay Bank, UBOC and UnionBanCal on their respective federal income tax returns in a manner consistent with the opinion set forth below.

Based upon our understanding of the transaction as described above and the above assumptions, and subject to the limitations contained herein, it is our opinion that the Bank Merger will constitute a "reorganization" within the meaning of Section 368(a) of the Code and that each of Monterey Bay Bank, UBOC and UnionBanCal will be a party to that reorganization within the meaning of Section 368(b) of the Code. In the event that any one or more of the facts, statements, descriptions, covenants, representations, warranties or assumptions upon which we have relied to issue this opinion is incorrect, our opinion might be adversely affected and may not be relied upon.

The opinion expressed herein is based upon and limited solely to the provisions of the Code and the statutes, judicial decisions and administrative regulations and rulings interpreting the Code, all as in effect on the date hereof and all of which are subject to change, either on a prospective or retroactive basis. We do not undertake any responsibility for updating or revising our opinion in consequence of any such change. We express only the opinion set forth above. This opinion does not address any other federal tax consequences or any state, local or foreign tax consequences that may result from the Bank Merger or any other transaction (including any transaction contemplated by the Agreement or undertaken in connection with, in contemplation of, or following the Bank Merger).

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and the reference to the name of our firm therein and under the caption "Legal Matters" in the Joint Proxy Statement/Prospectus furnished in connection with the offering of securities by UnionBanCal and the solicitation of proxies by the Board of Directors of Monterey Bay Bancorp. In giving our consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Securities and Exchange Commission thereunder.

Sincerely yours,

/s/Bingham McCutchen LLP

BINGHAM McCUTCHEN LLP

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Exhibit 8

EX-99.6

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Exhibit 99.6

Monterey Bay Bancorp, Inc.
567 Auto Center Drive
Watsonville, California 95076

May    , 2003

To: Stockholders of Monterey Bay Bancorp, Inc.:

Enclosed for your attention are two envelopes, one of which is WHITE and the other GREEN. They contain important information about your rights as a stockholder of Monterey Bay Bancorp, Inc. in the transaction briefly described below.

WHITE ENVELOPE    WHITE ENVELOPE    WHITE ENVELOPE

• The boards of directors of UnionBanCal Corporation, Union Bank of California, N.A., Monterey Bay Bancorp, Inc. and Monterey Bay Bank have agreed on a merger, which would result in Monterey Bay Bancorp, Inc. and Monterey Bay Bank merging with and into Union Bank of California, N.A., a wholly-owned subsidiary of UnionBanCal Corporation, with Union Bank of California, N.A. being the surviving entity.

•
Monterey Bay Bancorp, Inc. will hold a special stockholders' meeting to consider and vote on the merger proposal. The transaction is described in the enclosed proxy statement/prospectus (in WHITE envelope). Please carefully read the proxy statement/prospectus.

•
As soon as possible, please complete, date, sign and return the enclosed proxy card (in WHITE envelope). An envelope is enclosed for your convenience in returning the proxy card (in WHITE envelope). If you attend the special meeting, you may vote in person if you wish, even if you have previously returned your proxy card. The proxy may be revoked at any time prior to its exercise.

GREEN ENVELOPE    GREEN ENVELOPE    GREEN ENVELOPE

• In the merger, each of your shares of Monterey Bay Bancorp, Inc. outstanding at the closing of the merger will be converted into the right to receive merger consideration with an estimated value of between $25.27 and $27.18. The determination of the actual value of the merger consideration is described in detail in the enclosed proxy statement/prospectus.

•
You are entitled to indicate, subject to proration and other factors described in the proxy statement/prospectus, your preference of receiving merger consideration for each of your shares in cash or a fraction of a share of UnionBanCal Corporation common stock.

•
To indicate your preference, complete the enclosed letter of transmittal/election form (in GREEN envelope) and return it along with your Monterey Bay Bancorp, Inc. stock certificate(s) as described in the letter of transmittal/election form (in GREEN envelope). An envelope is enclosed for your convenience in returning these materials (in GREEN envelope).

•
Computershare Trust Company of New York, the exchange agent, must receive your stock certificates and your properly completed letter of transmittal/election form by 5:00 p.m. Eastern Time on [            ], 2003 in order for your choices as to the form of consideration you prefer to be considered with those of the other stockholders.

If you have any questions regarding this material, please contact the Information Agent as follows:

MacKenzie Partners, Inc.
CALL TOLL-FREE (800) 322-2885
105 Madison Avenue
New York, New York 10016
(212) 929-5500 (Call Collect)
E-mail: proxy@mackenziepartners.com

Sincerely,

C. Edward Holden
President and Chief Executive Officer

2

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Exhibit 99.6

Monterey Bay Bancorp, Inc. 567 Auto Center Drive Watsonville, California 95076