EXHIBIT 4.8

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                               GUARANTEE AGREEMENT


                                     BETWEEN


                            SILICON VALLEY BANCSHARES
                                 (AS GUARANTOR)


                                       AND


                            WILMINGTON TRUST COMPANY
                                  (AS TRUSTEE)



                                   DATED AS OF

                                   MAY 22, 1998


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                                TABLE OF CONTENTS



                                                                      PAGE
                                                                   
ARTICLE I.     DEFINITIONS...........................................   1

     SECTION 1.1  DEFINITIONS........................................   1

ARTICLE II.    TRUST INDENTURE ACT...................................   4

     SECTION 2.1  TRUST INDENTURE ACT; APPLICATION...................   4
     SECTION 2.2  LIST OF HOLDERS....................................   4
     SECTION 2.3  REPORTS BY THE GUARANTEE TRUSTEE...................   4
     SECTION 2.4  PERIODIC REPORTS TO THE GUARANTEE TRUSTEE..........   5
     SECTION 2.5  EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT...   5
     SECTION 2.6  EVENTS OF DEFAULT; WAIVER..........................   5
     SECTION 2.7  EVENT OF DEFAULT; NOTICE...........................   5
     SECTION 2.8  CONFLICTING INTERESTS..............................   6

ARTICLE III.   POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE....   6

     SECTION 3.1  POWERS AND DUTIES OF THE GUARANTEE TRUSTEE.........   6
     SECTION 3.2  CERTAIN RIGHTS OF GUARANTEE TRUSTEE................   7
     SECTION 3.3  INDEMNITY..........................................   9

ARTICLE IV.    GUARANTEE TRUSTEE.....................................   9

     SECTION 4.1  GUARANTEE TRUSTEE: ELIGIBILITY.....................   9
     SECTION 4.2  APPOINTMENT, REMOVAL AND RESIGNATION OF THE 
                   GUARANTEE TRUSTEE.................................  10

ARTICLE V.     GUARANTEE.............................................  10

     SECTION 5.1  GUARANTEE..........................................  10
     SECTION 5.2  WAIVER OF NOTICE AND DEMAND........................  10
     SECTION 5.3  OBLIGATIONS NOT AFFECTED...........................  11
     SECTION 5.4  RIGHTS OF HOLDERS..................................  12
     SECTION 5.5  GUARANTEE OF PAYMENT...............................  12
     SECTION 5.6  SUBROGATION........................................  12
     SECTION 5.7  INDEPENDENT OBLIGATIONS............................  12

                                       i


ARTICLE VI.    COVENANTS AND SUBORDINATION...........................  13

     SECTION 6.1  SUBORDINATION......................................  13
     SECTION 6.2  PARI PASSU GUARANTEES..............................  13

ARTICLE VII.   CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE..  13

     SECTION 7.1  GUARANTOR MAY CONSOLIDATE, ETC., ONLY ON 
                   CERTAIN TERMS.....................................  13
     SECTION 7.2  SUCCESSOR GUARANTOR SUBSTITUTED....................  14

ARTICLE VIII.  TERMINATION...........................................  14

     SECTION 8.1  TERMINATION........................................  14

ARTICLE IX.    MISCELLANEOUS.........................................  14

     SECTION 9.1  SUCCESSORS AND ASSIGNS.............................  14
     SECTION 9.2  AMENDMENTS.........................................  14
     SECTION 9.3  NOTICES............................................  15
     SECTION 9.4  BENEFIT............................................  16
     SECTION 9.5  INTERPRETATION.....................................  16
     SECTION 9.6  GOVERNING LAW......................................  16


                                       ii


                              CROSS-REFERENCE TABLE*



       Section of Trust                                    Section of
Indenture Act of 1939, as amended                      Guarantee Agreement
- ---------------------------------                      -------------------
                                                    
           310(a).                                           4.1(a)
           310(b).                                        4.1(c), 2.8
           310(c).                                        Inapplicable
           311(a).                                           2.2(b)
           311(b).                                           2.2(b)
           311(c).                                        Inapplicable
           312(a).                                           2.2(a)
           312(b).                                           2.2(b)
           313.                                               2.3
           314(a).                                            2.4
           314(b).                                        Inapplicable
           314(c).                                            2.5
           314(d).                                        Inapplicable
           314(e).                                       1.1, 2.5, 3.2
           314(f).                                         2.1, 3.2
           315(a).                                           3.1(d)
           315(b).                                            2.7
           315(c).                                            3.1
           315(d).                                           3.1(d)
           316(a).                                       1.1, 2.6, 5.4
           316(b).                                            5.3
           316(c).                                            9.2
           317(a).                                        Inapplicable
           317(b).                                        Inapplicable
           318(a).                                           2.1(b)
           318(b).                                            2.1
           318(c).                                           2.1(a)


- ----------
*  This Cross-Reference Table does not constitute part of the Guarantee 
   Agreement and shall not affect the interpretation of any of its terms 
   or provisions.

                             GUARANTEE AGREEMENT

     This GUARANTEE AGREEMENT, dated as of May 22, 1998, is executed and 
delivered by SILICON VALLEY BANCSHARES, a California corporation (the 
"Guarantor") having its 



principal office at 3003 Tasman Drive, Santa Clara, California, 95054, and 
WILMINGTON TRUST COMPANY, a Delaware banking corporation, as trustee (the 
"Guarantee Trustee"), for the benefit of the Holders from time to time of the 
Preferred Securities (as defined herein) of SVB CAPITAL I, a Delaware 
statutory business trust (the "Trust").

     WHEREAS, pursuant to an Amended and Restated Trust Agreement, dated as 
of May 22, 1998 (the "Trust Agreement"), among the Guarantor, as Depositor, 
Wilmington Trust Company as Property Trustee, Wilmington Trust Company, as 
Delaware Trustee, the Administrative Trustees named therein and the Holders 
from time to time of undivided beneficial interests in the assets of the 
Trust, the Trust issued $40,000,000 aggregate Liquidation Amount (as defined 
in the Trust Agreement) of its 8.25% Cumulative Trust Preferred Securities, 
Liquidation Amount $25 per Trust Preferred Security (the "Preferred 
Securities");

     WHEREAS, the Preferred Securities will be issued by the Trust and the 
proceeds thereof, together with the proceeds from the issuance of the Trust's 
Common Securities (as defined below), will be used to purchase the Debentures 
(as defined in the Trust Agreement) of the Guarantor which were deposited 
with Wilmington Trust Company, as Property Trustee under the Trust Agreement, 
as trust assets;

     WHEREAS, as an incentive for the Holders to purchase the Preferred 
Securities, the Guarantor desires irrevocably and unconditionally to agree, 
to the extent set forth herein, to pay to the Holders of the Preferred 
Securities the Guarantee Payments (as defined herein) and to make certain 
other payments on the terms and conditions set forth herein.

     NOW, THEREFORE, in consideration of the purchase by each Holder of 
Preferred Securities, which purchase the Guarantor hereby agrees shall 
benefit the Guarantor, the Guarantor executes and delivers this Guarantee 
Agreement and pursuant to Section 5.1 hereof extends the Guarantee for the 
benefit of the Holders from time to time of the Preferred Securities.

                          ARTICLE I.  DEFINITIONS

     SECTION I.1  DEFINITIONS.

     As used in this Guarantee Agreement, the terms set forth below shall, 
unless the context otherwise requires, have the following meanings.  
Capitalized or otherwise defined terms used but not otherwise defined herein 
shall have the meanings assigned to such terms in the Trust Agreement and the 
Indenture (as defined herein), each as in effect on the date hereof.

     "AFFILIATE" of any specified Person means any other Person directly or 
indirectly controlling or controlled by or under direct or indirect common 
control with such specified Person; PROVIDED, HOWEVER, that an Affiliate of 
the Guarantor shall not be deemed to be an Affiliate of the Trust.  For the 
purposes of this definition, "CONTROL" when used with respect to any 
specified Person means the power to direct the management and policies of 
such Person, 

                                      2


directly or indirectly, whether through the ownership of voting securities, 
by contract or otherwise; and the terms "CONTROLLING" and "CONTROLLED" have 
meanings correlative to the foregoing.

     "BOARD OF DIRECTORS" means either the board of directors of the 
Guarantor or any committee of that board duly authorized to act hereunder.

     "COMMON SECURITIES" means the securities representing common 
undivided beneficial interests in the assets of the Trust.

     "EVENT OF DEFAULT" means a default by the Guarantor on any of its 
payment or other obligations under this Guarantee Agreement; provided, 
however, that, except with respect to a default in payment of any Guarantee 
Payments, the Guarantor shall have received notice of default and shall not 
have cured such default within 90 days after receipt of such notice.

     "GUARANTEE" has the meaning set forth in Section 5.1.

     "GUARANTEE PAYMENTS" means the following payments or distributions, 
without duplication, with respect to the Preferred Securities, to the extent 
not paid or made by or on behalf of the Trust: (i) any accrued and unpaid 
Distributions (as defined in the Trust Agreement) required to be paid on the 
Preferred Securities, to the extent the Trust shall have funds on hand 
available therefor at such time, (ii) the applicable Redemption Price (as 
defined in the Trust Agreement), to the extent the Trust shall have funds on 
hand available therefor at such time, and (iii) upon a voluntary or 
involuntary termination, winding up or liquidation of the Trust, unless 
Debentures are distributed to the Holders, the lesser of (a) the aggregate of 
the Liquidation Distribution (as defined in the Trust Agreement) and (b) the 
amount of assets of the Trust remaining available for distribution to Holders 
of Preferred Securities after satisfaction of liabilities to creditors of the 
Trust as required by applicable law.

     "GUARANTEE TRUSTEE" means Wilmington Trust Company, until a Successor 
Guarantee Trustee has been appointed and has accepted such appointment 
pursuant to the terms of this Guarantee Agreement, and thereafter means each 
such Successor Guarantee Trustee.

     "HOLDER" means any holder, as registered on the books and records of the 
Trust, of any Preferred Securities; PROVIDED, HOWEVER, that in determining 
whether the holders of the requisite percentage of Preferred Securities have 
given any request, notice, consent or waiver hereunder, "Holder" shall not 
include the Guarantor, the Guarantee Trustee, or any Affiliate of the 
Guarantor or the Guarantee Trustee.

     "INDENTURE" means the Junior Subordinated Indenture dated as of May 22, 
1998, as supplemented and amended between the Guarantor and Wilmington Trust 
Company, as trustee.

     "LIST OF HOLDERS" has the meaning specified in Section 2.2(a).

                                      3


     "MAJORITY IN LIQUIDATION AMOUNT OF THE PREFERRED SECURITIES" means, 
except as provided by the Trust Indenture Act, a vote by the Holder(s), 
voting separately as a class, of more than 50% of the Liquidation Amount of 
all then outstanding Preferred Securities issued by the Trust.

     "OFFICERS' CERTIFICATE" means, with respect to any Person, a certificate 
signed by the Chairman or a Vice Chairman of the Board of Directors of such 
Person or the President or a Vice President of such Person, and by the Chief 
Financial Officer, the Secretary or an Assistant Secretary of such Person, 
and delivered to the Guarantee Trustee.  Any Officers' Certificate delivered 
with respect to compliance with a condition or covenant provided for in this 
Guarantee Agreement shall include:

          (1)  a statement that each officer signing the Officers' 
Certificate has read the covenant or condition and the definitions relating 
thereto;

          (2)  a brief statement of the nature and scope of the examination 
or investigation undertaken by each officer in rendering the Officers' 
Certificate;

          (3)  a statement that each officer has made such examination or 
investigation as, in such officer's opinion, is necessary to enable such 
officer to express an informed opinion as to whether or not such covenant or 
condition has been complied with; and

          (4)  a statement as to whether, in the opinion of each officer, 
such condition or covenant has been complied with.

     "OTHER GUARANTEES" means any guarantees similar to the Guarantee issued, 
from time to time, by the Guarantor on behalf of holders of one or more 
series of Preferred Securities issued by any SVB Trust (as defined in the 
Indenture) other than the Trust.

     "PERSON" means a legal person, including any individual, corporation, 
estate, partnership, joint venture, association, joint stock company, limited 
liability company, trust, unincorporated association, or government or any 
agency or political subdivision thereof, or any other entity of whatever 
nature.

     "RESPONSIBLE OFFICER" means, with respect to the Guarantee Trustee, any 
officer of the Corporate Trust Department of the Guarantee Trustee and also 
means, with respect to a particular corporate trust matter, any other officer 
to whom such matter is referred because of that officer's knowledge of and 
familiarity with the particular subject.

     "SECURITIES ACT" means the Securities Act of 1933, as amended.

     "SUCCESSOR GUARANTEE TRUSTEE" means a successor Guarantee Trustee 
possessing the qualifications to act as Guarantee Trustee under Section 4.1.

                                      4


     "TRUST INDENTURE ACT" means the Trust Indenture Act of 1939, as amended.

                         ARTICLE II.  TRUST INDENTURE ACT

     SECTION II.1  TRUST INDENTURE ACT; APPLICATION.

     (1)  This Guarantee Agreement is subject to the provisions of the Trust 
Indenture Act that are required to be part of this Guarantee Agreement and 
shall, to the extent applicable, be governed by such provisions.

     (2)  If and to the extent that any provision of this Guarantee Agreement 
limits, qualifies or conflicts with the duties imposed by Sections 310 to 
317, inclusive, of the Trust Indenture Act, such imposed duties shall control.

     SECTION II.2  LIST OF HOLDERS.

     (1)  The Guarantor shall furnish or cause to be furnished to the 
Guarantee Trustee (a) semiannually, on or before January 15 and July 15 of 
each year, a list, in such form as the Guarantee Trustee may reasonably 
require, of the names and addresses of the Holders ("List of Holders") as of 
a date not more than 15 days prior to the delivery thereof, and (b) at such 
other times as the Guarantee Trustee may request in writing, within 30 days 
after the receipt by the Guarantor of any such request, a List of Holders as 
of a date not more than 15 days prior to the time such list is furnished, in 
each case to the extent such information is in the possession or control of 
the Guarantor and is not identical to a previously supplied list of Holders 
or has not otherwise been received by the Guarantee Trustee in its capacity 
as such.  The Guarantee Trustee may destroy any List of Holders previously 
given to it on receipt of a new List of Holders.

     (2)  The Guarantee Trustee shall comply with its obligations under 
Section 311(a), Section 311(b) and Section 312(b) of the Trust Indenture Act.

     SECTION II.3  REPORTS BY THE GUARANTEE TRUSTEE.

     Not later than March 31 of each year, commencing on the year beginning 
January 1, 1999, the Guarantee Trustee shall provide to the Holders such 
reports as are required by Section 313 of the Trust Indenture Act, if any, in 
the form and in the manner provided by Section 313 of the Trust Indenture 
Act.  The Guarantee Trustee shall also comply with the requirements of 
Section 313(d) of the Trust Indenture Act.

     SECTION II.4  PERIODIC REPORTS TO THE GUARANTEE TRUSTEE.

     The Guarantor shall provide to the Guarantee Trustee, the Securities and 
Exchange Commission and the Holders such documents, reports and information, 
if any, as required by 

                                      5


Section 314 of the Trust Indenture Act and the compliance certificate 
required by Section 314 of the Trust Indenture Act, in the form, in the 
manner and at the times required by Section 314 of the Trust Indenture Act.

     SECTION II.5  EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT.

     The Guarantor shall provide to the Guarantee Trustee, on an annual 
basis, such evidence of compliance with such conditions precedent, if any, 
provided for in this Guarantee Agreement that relate to any of the matters 
set forth in Section 314(c) of the Trust Indenture Act.  Any certificate or 
opinion required to be given by an officer pursuant to Section 314(c)(1) may 
be given in the form of an Officers' Certificate.

     SECTION II.6  EVENTS OF DEFAULT; WAIVER.

     The Holders of a Majority in Liquidation Amount of the Preferred 
Securities may, by vote, on behalf of the Holders, waive any past Event of 
Default and its consequences.  Upon such waiver, any such Event of Default 
shall cease to exist, and any Event of Default arising therefrom shall be 
deemed to have been cured, for every purpose of this Guarantee Agreement, but 
no such waiver shall extend to any subsequent or other default or Event of 
Default or impair any right consequent therefrom.

     SECTION II.7  EVENT OF DEFAULT; NOTICE.

     (1)  The Guarantee Trustee shall, within 90 days after the occurrence of 
a default which with notice or the passage of time, or both, could become an 
Event of Default, transmit by mail, first class postage prepaid, to the 
Holders, notices of all such defaults known to the Guarantee Trustee, unless 
such defaults have been cured before the giving of such notice, provided, 
that, except in the case of a default in the payment of a Guarantee Payment, 
the Guarantee Trustee shall be protected in withholding such notice if and so 
long as the Board of Directors, the executive committee or a trust committee 
of directors and/or Responsible Officers of the Guarantee Trustee in good 
faith determines that the withholding of such notice is in the interests of 
the Holders.

     (2)  The Guarantee Trustee shall not be deemed to have knowledge of any 
such default unless the Guarantee Trustee shall have received written notice, 
or a Responsible Officer charged with the administration of this Guarantee 
Agreement shall have obtained written notice, of such default.

     SECTION II.8  CONFLICTING INTERESTS.

     The Trust Agreement shall be deemed to be specifically described in this 
Guarantee Agreement for the purposes of clause (i) of the first proviso 
contained in Section 310(b) of the Trust Indenture Act.

                                      6


      ARTICLE III.  POWERS, DUTIES AND RIGHTS OF THE GUARANTEE TRUSTEE

     SECTION III.1  POWERS AND DUTIES OF THE GUARANTEE TRUSTEE.

     (1)  This Guarantee shall be held by the Guarantee Trustee for the 
benefit of the Holders, and the Guarantee Trustee shall not transfer this 
Guarantee to any Person except to a Holder exercising his or her rights 
pursuant to Section 5.4(iv) or to a Successor Guarantee Trustee on acceptance 
by such Successor Guarantee Trustee of its appointment to act as Successor 
Guarantee Trustee.  The right, title and interest of the Guarantee Trustee 
shall automatically vest in any Successor Guarantee Trustee, upon acceptance 
by such Successor Guarantee Trustee of its appointment hereunder, and such 
vesting and cessation of title shall be effective whether or not conveyancing 
documents have been executed and delivered pursuant to the appointment of 
such Successor Guarantee Trustee.

     (2)  If an Event of Default has occurred and is continuing, the 
Guarantee Trustee shall enforce this Guarantee for the benefit of the Holders.

     (3)  The Guarantee Trustee, before the occurrence of any Event of 
Default and after the curing of all Events of Default that may have occurred, 
shall undertake to perform only such duties as are specifically set forth in 
this Guarantee Agreement, and no implied covenants shall be read into this 
Guarantee Agreement against the Guarantee Trustee.  In case an Event of 
Default has occurred (that has not been cured or waived pursuant to Section 
2.6), the Guarantee Trustee shall exercise such of the rights and powers 
vested in it by this Guarantee Agreement, and use the same degree of care and 
skill in its exercise thereof, as a prudent person would exercise or use 
under the circumstances in the conduct of his or her own affairs.

     (4)  No provision of this Guarantee Agreement shall be construed to 
relieve the Guarantee Trustee from liability for its own negligent action, 
its own negligent failure to act or its own willful misconduct, except that:

          (1)  prior to the occurrence of any Event of Default and after the 
     curing or waiving of all such Events of Default that may have occurred:

               (1)  the duties and obligations of the Guarantee Trustee shall 
          be determined solely by the express provisions of this Guarantee 
          Agreement, and the Guarantee Trustee shall not be liable except for 
          the performance of such duties and obligations as are specifically 
          set forth in this Guarantee Agreement; and

               (2)  in the absence of bad faith on the part of the Guarantee 
          Trustee, the Guarantee Trustee may conclusively rely, as to the truth 
          of the statements and the correctness of the opinions expressed 
          therein, upon any certificates or opinions furnished to the Guarantee 
          Trustee and conforming to the requirements of this 

                                      7


          Guarantee Agreement; but in the case of any such certificates or 
          opinions that by any provision hereof or of the Trust Indenture Act 
          are specifically required to be furnished to the Guarantee Trustee, 
          the Guarantee Trustee shall be under a duty to examine the same to 
          determine whether or not they conform to the requirements of this 
          Guarantee Agreement;

          (2)  The Guarantee Trustee shall not be liable for any error of 
     judgment made in good faith by a Responsible Officer of the Guarantee 
     Trustee, unless it shall be proved that the Guarantee Trustee was 
     negligent in ascertaining the pertinent facts upon which such judgment 
     was made;

          (3)  the Guarantee Trustee shall not be liable with respect to any 
     action taken or omitted to be taken by it in good faith in accordance 
     with the direction of the Holders of not less than a Majority in 
     Liquidation Amount of the Preferred Securities relating to the time, 
     method and place of conducting any proceeding for any remedy available 
     to the Guarantee Trustee, or exercising any trust or power conferred 
     upon the Guarantee Trustee under this Guarantee Agreement; and

          (4)  no provision of this Guarantee Agreement shall require the 
     Guarantee Trustee to expend or risk its own funds or otherwise incur 
     personal financial liability in the performance of any of its duties or 
     in the exercise of any of its rights or powers, if the Guarantee Trustee 
     shall have reasonable grounds for believing that the repayment of such 
     funds or liability is not reasonably assured to it under the terms of 
     this Guarantee Agreement or adequate indemnity against such risk or 
     liability is not reasonably assured to it.

     SECTION III.2  CERTAIN RIGHTS OF GUARANTEE TRUSTEE.

     (1)  Subject to the provisions of Section 3.1:

          (1)  The Guarantee Trustee may rely and shall be fully protected in 
     acting or refraining from acting upon any resolution, certificate, 
     statement, instrument, opinion, report, notice, request, direction, 
     consent, order, bond, debenture, note, other evidence of indebtedness or 
     other paper or document reasonably believed by it to be genuine and to 
     have been signed, sent or presented by the proper party or parties.

          (2)  Any direction or act of the Guarantor contemplated by this 
     Guarantee Agreement shall be sufficiently evidenced by an Officers' 
     Certificate unless otherwise prescribed herein.

          (3)  Whenever, in the administration of this Guarantee Agreement, 
     the Guarantee Trustee shall deem it desirable that a matter be proved or 
     established before taking, suffering or omitting to take any action 
     hereunder, the Guarantee Trustee (unless 

                                      8


     other evidence is herein specifically prescribed) may, in the absence of 
     bad faith on its part, request and rely upon an Officers' Certificate 
     which, upon receipt of such request from the Guarantee Trustee, shall be 
     promptly delivered by the Guarantor.

          (4)  The Guarantee Trustee may consult with legal counsel, and the 
     written advice or opinion of such legal counsel with respect to legal 
     matters shall be full and complete authorization and protection in 
     respect of any action taken, suffered or omitted to be taken by it 
     hereunder in good faith and in accordance with such advice or opinion.  
     Such legal counsel may be legal counsel to the Guarantor or any of its 
     Affiliates and may be one of its employees.  The Guarantee Trustee shall 
     have the right at any time to seek instructions concerning the 
     administration of this Guarantee Agreement from any court of competent 
     jurisdiction.

          (5)  The Guarantee Trustee shall be under no obligation to exercise 
     any of the rights or powers vested in it by this Guarantee Agreement at 
     the request or direction of any Holder, unless such Holder shall have 
     provided to the Guarantee Trustee such adequate security and indemnity 
     as would satisfy a reasonable person in the position of the Guarantee 
     Trustee, against the costs, expenses (including attorneys' fees and 
     expenses) and liabilities that might be incurred by it in complying with 
     such request or direction, including such reasonable advances as may be 
     requested by the Guarantee Trustee; provided that, nothing contained in 
     this Section 3.2(a)(v) shall be taken to relieve the Guarantee Trustee, 
     upon the occurrence of an Event of Default, of its obligation to 
     exercise the rights and powers vested in it by this Guarantee Agreement.

          (6)  The Guarantee Trustee shall not be bound to make any 
     investigation into the facts or matters stated in any resolution, 
     certificate, statement, instrument, opinion, report, notice, request, 
     direction, consent, order, bond, debenture, note, other evidence of 
     indebtedness or other paper or document, but the Guarantee Trustee, in 
     its discretion, may make such further inquiry or investigation into such 
     facts or matters as it may see fit.

          (7)  The Guarantee Trustee may execute any of the trusts or powers 
     hereunder or perform any duties hereunder either directly or by or 
     through its agents or attorneys, and the Guarantee Trustee shall not be 
     responsible for any misconduct or negligence on the part of any such 
     agent or attorney appointed with due care by it hereunder.

          (8)  Whenever in the administration of this Guarantee Agreement the 
     Guarantee Trustee shall deem it desirable to receive instructions with 
     respect to enforcing any remedy or right or taking any other action 
     hereunder, the Guarantee Trustee (A) may request instructions from the 
     Holders, (B) may refrain from enforcing such remedy or right or taking 
     such other action until such instructions are received, and (C) shall be 
     protected in acting in accordance with such instructions.

                                      9


     (2)  No provision of this Guarantee Agreement shall be deemed to impose 
any duty or obligation on the Guarantee Trustee to perform any act or acts or 
exercise any right, power, duty or obligation conferred or imposed on it in 
any jurisdiction in which it shall be illegal, or in which the Guarantee 
Trustee shall be unqualified or incompetent in accordance with applicable 
law, to perform any such act or acts or to exercise any such right, power, 
duty or obligation.  No permissive power or authority available to the 
Guarantee Trustee shall be construed to be a duty to act in accordance with 
such power and authority.

     SECTION III.3  INDEMNITY.

     The Guarantor agrees to indemnify the Guarantee Trustee for, and to hold 
it harmless against, any loss, liability or expense incurred without 
negligence or bad faith on the part of the Guarantee Trustee, arising out of 
or in connection with the acceptance or administration of this Guarantee 
Agreement, including the costs and expenses of defending itself against any 
claim or liability in connection with the exercise or performance of any of 
its powers or duties hereunder.

                       ARTICLE IV.  GUARANTEE TRUSTEE

     SECTION IV.1  GUARANTEE TRUSTEE: ELIGIBILITY.

     (1)  There shall at all times be a Guarantee Trustee which shall:

          (1)  not be an Affiliate of the Guarantor; and

          (2)  be a Person that is eligible pursuant to the Trust Indenture 
     Act to act as such and has a combined capital and surplus of at least 
     $50,000,000, and shall be a corporation meeting the requirements of 
     Section 310(a) of the Trust Indenture Act.  If such corporation 
     publishes reports of condition at least annually, pursuant to law or to 
     the requirements of the supervising or examining authority, then, for 
     the purposes of this Section 4.1(a)(ii) and to the extent permitted by 
     the Trust Indenture Act, the combined capital and surplus of such 
     corporation shall be deemed to be its combined capital and surplus as 
     set forth in its most recent report of condition so published.

     (2)  If at any time the Guarantee Trustee shall cease to be eligible to 
so act under Section 4.1(a), the Guarantee Trustee shall immediately resign 
in the manner and with the effect set out in Section 4.2(c).

     (3)  If the Guarantee Trustee has or shall acquire any "conflicting 
interest" within the meaning of Section 310(b) of the Trust Indenture Act, 
the Guarantee Trustee and Guarantor shall in all respects comply with the 
provisions of Section 310(b) of the Trust Indenture Act.

     SECTION IV.2  APPOINTMENT, REMOVAL AND RESIGNATION OF THE GUARANTEE 
TRUSTEE.

                                      10


     (1)  Subject to Section 4.2(b), the Guarantee Trustee may be appointed 
or removed without cause at any time by the Guarantor.

     (2)  The Guarantee Trustee shall not be removed until a Successor 
Guarantee Trustee has been appointed and has accepted such appointment by 
written instrument executed by such Successor Guarantee Trustee and delivered 
to the Guarantor.

     (3)  The Guarantee Trustee appointed hereunder shall hold office until a 
Successor Guarantee Trustee shall have been appointed or until its removal or 
resignation.  The Guarantee Trustee may resign from office (without need for 
prior or subsequent accounting) by an instrument in writing executed by the 
Guarantee Trustee and delivered to the Guarantor, which resignation shall not 
take effect until a Successor Guarantee Trustee has been appointed and has 
accepted such appointment by instrument in writing executed by such Successor 
Guarantee Trustee and delivered to the Guarantor and the resigning Guarantee 
Trustee.

     (4)  If no Successor Guarantee Trustee shall have been appointed and 
accepted appointment as provided in this Section 4.2 within 60 days after 
delivery to the Guarantor of an instrument of resignation, the resigning 
Guarantee Trustee may petition, at the expense of the Guarantor, any court of 
competent jurisdiction for appointment of a Successor Guarantee Trustee.  
Such court may thereupon, after prescribing such notice, if any, as it may 
deem proper, appoint a Successor Guarantee Trustee.

                            ARTICLE V.  GUARANTEE

     SECTION V.1  GUARANTEE.

     The Guarantor irrevocably and unconditionally agrees to pay in full on a 
subordinated basis to the Holders the Guarantee Payments (without duplication 
of amounts theretofore paid by or on behalf of the Trust), as and when due, 
regardless of any defense, right of set-off or counterclaim which the Trust 
may have or assert other than the defense of payment (the "Guarantee").  The 
Guarantee is a continuing guarantee, and the Guarantor fully, knowingly and 
unconditionally waives any right the Guarantor may have to revoke the 
Guarantee as to any future transactions under Section 2815 of the California 
Civil Code or otherwise.  The Guarantor's obligation to make a Guarantee 
Payment may be satisfied by direct payment of the required amounts by the 
Guarantor to the Holders or by causing the Trust to pay such amounts to the 
Holders.

     SECTION V.2  WAIVER OF NOTICE AND DEMAND.

     The Guarantor hereby waives notice of acceptance of the Guarantee and of 
any liability to which it applies or may apply, presentment, demand for 
payment, any right to require a proceeding first against the Guarantee 
Trustee, Trust or any other Person before proceeding 

                                      11


against the Guarantor, protest, notice of nonpayment, notice of dishonor, 
notice of redemption and all other notices and demands.

     SECTION V.3  OBLIGATIONS NOT AFFECTED.

     The obligations, covenants, agreements and duties of the Guarantor under 
this Guarantee Agreement shall in no way be affected or impaired by reason of 
the happening from time to time of any of the following:

     (1)  the release or waiver, by operation of law or otherwise, of the 
performance or observance by the Trust of any express or implied agreement, 
covenant, term or condition relating to the Preferred Securities to be 
performed or observed by the Trust;

     (2)  the extension of time for the payment by the Trust of all or any 
portion of the Distributions (other than an extension of time for payment of 
Distributions that results from the extension of any interest payment period 
on the Debentures as provided in the Indenture), Redemption Price, 
Liquidation Distribution or any other sums payable under the terms of the 
Preferred Securities or the extension of time for the performance of any 
other obligation under, arising out of, or in connection with, the Preferred 
Securities;

     (3)  any failure, omission, delay or lack of diligence on the part of 
the Holders to enforce, assert or exercise any right, privilege, power or 
remedy conferred on the Holders pursuant to the terms of the Preferred 
Securities, or any action on the part of the Trust granting indulgence or 
extension of any kind;

     (4)  the voluntary or involuntary liquidation, dissolution, sale of any 
collateral, receivership, insolvency, bankruptcy, assignment for the benefit 
of creditors, reorganization, arrangement, composition or readjustment of 
debt of, or other similar proceedings affecting, the Trust or any of the 
assets of the Trust;

     (5)  any invalidity of, or defect or deficiency in, the Preferred 
Securities;

     (6)  the settlement or compromise of any obligation guaranteed hereby or 
hereby incurred; or

     (7)  any other circumstance whatsoever that might otherwise constitute a 
legal or equitable discharge or defense of a guarantor, it being the intent 
of this Section 5.3 that the obligations of the Guarantor hereunder shall be 
absolute and unconditional under any and all circumstances.

There shall be no obligation of the Holders to give notice to, or obtain the 
consent of, the Guarantor with respect to the happening of any of the 
foregoing.  In addition to the foregoing provisions of this Section 5.3 and 
Section 5.2, Guarantor waives all rights and defenses arising out 

                                      12


of an election of remedies by Guarantee Trustee or Holders, even though that 
election of remedies has destroyed the Guarantor's rights of subrogation and 
reimbursement against the principal by operation of Section 580d of the 
California Code of Civil Procedure or otherwise.

     SECTION V.4  RIGHTS OF HOLDERS.

     The Guarantor expressly acknowledges that: (i) this Guarantee will be 
deposited with the Guarantee Trustee to be held for the benefit of the 
Holders; (ii) the Guarantee Trustee has the right to enforce this Guarantee 
on behalf of the Holders; (iii) the Holders of a Majority in Liquidation 
Amount of the Preferred Securities have the right to direct the time, method 
and place of conducting any proceeding for any remedy available to the 
Guarantee Trustee in respect of this Guarantee Agreement or exercising any 
trust or power conferred upon the Guarantee Trustee under this Guarantee 
Agreement; and (iv) any Holder may institute a legal proceeding directly 
against the Guarantor to enforce its rights under this Guarantee Agreement, 
without first instituting a legal proceeding against the Guarantee Trustee, 
the Trust or any other Person.

     SECTION V.5  GUARANTEE OF PAYMENT.

     This Guarantee creates a guarantee of payment and not of collection.  
This Guarantee will not be discharged except by payment of the Guarantee 
Payments in full (without duplication of amounts theretofore paid by the 
Trust) or upon distribution of Debentures to Holders as provided in the Trust 
Agreement.

     SECTION V.6  SUBROGATION.

     The Guarantor shall be subrogated to all (if any) rights of the Holders 
against the Trust in respect of any amounts paid to the Holders by the 
Guarantor under this Guarantee Agreement and shall have the right to waive 
payment by the Trust pursuant to Section 5.1; PROVIDED, HOWEVER, that the 
Guarantor shall not (except to the extent required by mandatory provisions of 
law) be entitled to enforce or exercise any rights which it may acquire by 
way of subrogation or any indemnity, reimbursement or other agreement, in all 
cases as a result of payment under this Guarantee, if, at the time of any 
such payment, any amounts are due and unpaid under this Guarantee.  If any 
amount shall be paid to the Guarantor in violation of the preceding sentence, 
the Guarantor agrees to hold such amount in trust for the Holders and to pay 
over such amount to the Holders.

     SECTION V.7  INDEPENDENT OBLIGATIONS.

     The Guarantor acknowledges that its obligations hereunder are 
independent of the obligations of the Trust with respect to the Preferred 
Securities and that the Guarantor shall be liable as principal and as debtor 
hereunder to make Guarantee Payments pursuant to the terms of this Guarantee 
Agreement notwithstanding the occurrence of any event referred to in 
subsections (a) through (g), inclusive, of Section 5.3 hereof.

                                      13


                  ARTICLE VI.  COVENANTS AND SUBORDINATION

     SECTION VI.1  SUBORDINATION.

     The obligations of the Guarantor under this Guarantee will constitute 
unsecured obligations of the Guarantor and will rank subordinate and junior 
in right of payment to all Senior and Subordinated Debt in the same manner as 
Debentures.

     SECTION VI.2  PARI PASSU GUARANTEES.

     The obligations of the Guarantor under this Guarantee shall rank PARI 
PASSU with the obligations of the Guarantor under all Other Guarantees.

             ARTICLE VII.  CONSOLIDATION, MERGER, CONVEYANCE,
                             TRANSFER OR LEASE

     SECTION VII.1  GUARANTOR MAY CONSOLIDATE, ETC., ONLY ON CERTAIN TERMS.

     The Guarantor shall not consolidate with or merge into any other Person 
or convey, transfer or lease its properties and assets substantially as an 
entirety to any Person, and no Person shall consolidate with or merge into 
the Guarantor or convey, transfer or lease its properties and assets 
substantially as an entirety to the Guarantor, unless:

     (1)  in case the Guarantor shall consolidate with or merge into another 
Person or convey, transfer or lease its properties and assets substantially 
as an entirety to any Person, the Person formed by such consolidation or into 
which the Guarantor is merged or the Person which acquires by conveyance or 
transfer, or which leases, the properties and assets of the Guarantor 
substantially as an entirety shall be a corporation, partnership or trust 
organized and existing under the laws of the United States of America or any 
State or the District of Columbia, and shall expressly assume the Guarantor's 
obligations under this Guarantee;

     (2)  immediately after giving effect thereto, no Event of Default, and 
no event which, after notice or lapse of time, or both, would become an Event 
of Default, shall have happened and be continuing;

     (3)  such consolidation, merger, conveyance, transfer or lease is 
permitted under the Trust Agreement and the Indenture and does not give rise 
to any breach or violation of the Trust Agreement or the Indenture; and

     (4)  the Guarantor has delivered to the Guarantee Trustee an Officers' 
Certificate and an Opinion of Counsel, each stating that such consolidation, 
merger, conveyance, transfer or lease and assumption of the Guarantor's 
obligations under this Guarantee Agreement comply 

                                      14


with this Article and that all conditions precedent herein provided for 
relating to such transaction have been complied with; and the Guarantee 
Trustee, subject to Section 3.1 hereof, may rely upon such Officers' 
Certificate and Opinion of Counsel as conclusive evidence that such 
transaction complies with this Section 7.1.

     SECTION VII.2  SUCCESSOR GUARANTOR SUBSTITUTED.

     Upon any consolidation or merger by the Guarantor with or into any other 
Person, or any conveyance, transfer or lease by the Guarantor of its 
properties and assets substantially as an entirety to any Person in 
accordance with Section 7.1, the successor Person formed by such 
consolidation or into which the Guarantor is merged or to which such 
conveyance, transfer or lease is made shall succeed to, and be substituted 
for, and may exercise every right and power of, the Guarantor under this 
Guarantee Agreement with the same effect as if such successor Person had been 
named as the Guarantor herein; and in the event of any such conveyance, 
transfer or lease the Guarantor shall be discharged from all obligations and 
covenants under this Guarantee Agreement.

                        ARTICLE VIII.  TERMINATION

     SECTION VIII.1  TERMINATION.

     This Guarantee Agreement shall terminate and be of no further force and 
effect upon the earliest of (i) full payment of the applicable Redemption 
Price of all Preferred Securities, (ii) the distribution of Debentures to the 
Holders in exchange for all of the Preferred Securities or (iii) full payment 
of the amounts payable in accordance with the Trust Agreement upon 
liquidation of the Trust.  Notwithstanding the foregoing clauses (i) through 
(iii), this Guarantee Agreement will continue to be effective or will be 
reinstated if it has been terminated pursuant to one of such clauses (i) 
through (iii), as the case may be, if at any time any Holder must restore 
payment of any sums paid with respect to Preferred Securities or this 
Guarantee Agreement.

                        ARTICLE IX.  MISCELLANEOUS

     SECTION IX.1  SUCCESSORS AND ASSIGNS.

     All guarantees and agreements contained in this Guarantee Agreement 
shall bind the successors, assigns, receivers, trustees and representatives 
of the Guarantor and shall inure to the benefit of the Holders of the 
Preferred Securities then outstanding.  Except in connection with a 
consolidation, merger or sale involving the Guarantor that is permitted under 
Article VII hereof and Article VIII of the Indenture, the Guarantor shall not 
assign its obligations hereunder.

                                      15


     SECTION IX.2  AMENDMENTS.

     Except with respect to any changes which do not adversely affect the 
rights of the Holders in any material respect (in which case no vote will be 
required), this Guarantee Agreement may not be amended without the prior 
approval of the Holders of not less than a Majority in Liquidation Amount of 
the Preferred Securities.  The provisions of Article VI of the Trust 
Agreement concerning meetings of the Holders shall apply to the giving of 
such approval.

     SECTION IX.3  NOTICES.

     Any notice, request or other communication required or permitted to be 
given hereunder shall be in writing, duly signed by the party giving such 
notice, and delivered, telecopied or mailed by first class mail as follows:

     (1)  if given to the Guarantor, to the address set forth below or such 
other address, facsimile number or to the attention of such other Person as 
the Guarantor may give notice to the Holders:

          Silicon Valley Bancshares
          3003 Tasman Drive
          Santa Clara, California 95054

          Facsimile No.:  (408) 496-2405
          Attention:  Christopher T. Lutes

     (2)  if given to the Trust, in care of the Guarantee 
Trustee, at the Trust's (and the Guarantee Trustee's) address set 
forth below or such other address as the Guarantee Trustee on 
behalf of the Trust may give notice to the Holders:

          SVB Capital I
          c/o Silicon Valley Bancshares
          3003 Tasman Drive
          Santa Clara, California, 95054

          Facsimile No.:  (408) 496-2405
          Attention:  Christopher T. Lutes

          with a copy to:

          Wilmington Trust Company
          Rodney Square North
          1100 North Market Street

                                      16


          Wilmington, Delaware 19890-0001

          Facsimile No.:  (302) 651-1576
          Attention:  Corporate Trust Administration

     (3)  if given to any Holder, at the address set forth on the books and 
records of the Trust.

     All notices hereunder shall be deemed to have been given when received 
in person, telecopied with receipt confirmed, or mailed by first class mail, 
postage prepaid, except that if a notice or other document is refused 
delivery or cannot be delivered because of a changed address of which no 
notice was given, such notice or other document shall be deemed to have been 
delivered on the date of such refusal or inability to deliver.

     SECTION IX.4  BENEFIT.

     This Guarantee is solely for the benefit of the Holders and is not 
separately transferable from the Preferred Securities.

     SECTION IX.5  INTERPRETATION.

     In this Guarantee Agreement, unless the context otherwise requires:

     (1)  capitalized terms used in this Guarantee Agreement but not defined 
in the preamble hereto have the respective meanings assigned to them in 
Section 1.1;

     (2)  a term defined anywhere in this Guarantee Agreement has the same 
meaning throughout;

     (3)  all references to "the Guarantee Agreement" or "this Guarantee 
Agreement" are to this Guarantee Agreement as modified, supplemented or 
amended from time to time;

     (4)  all references in this Guarantee Agreement to Articles and Sections 
are to Articles and Sections of this Guarantee Agreement unless otherwise 
specified;

     (5)  a term defined in the Trust Indenture Act has the same meaning when 
used in this Guarantee Agreement unless otherwise defined in this Guarantee 
Agreement or unless the context otherwise requires;

     (6)  a reference to the singular includes the plural and vice versa; and

     (7)  the masculine, feminine or neuter genders used herein shall include 
the masculine, feminine and neuter genders.

                                      17


     SECTION IX.6  GOVERNING LAW.

     THIS GUARANTEE AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED AND 
INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF CALIFORNIA WITHOUT 
REGARD TO THE CONFLICT OF LAW PRINCIPLES THEREOF.

     This instrument may be executed in any number of counterparts, each of 
which so executed shall be deemed to be an original, but all such 
counterparts shall together constitute but one and the same instrument.

     THIS GUARANTEE AGREEMENT is executed as of the day and year first above 
written.

                                       Silicon Valley Bancshares


                                       By:      /s/ John C. Dean
                                             --------------------------------
                                       Name:   John C. Dean
                                       Title:  President and Chief Executive 
                                               Officer


                                       Wilmington Trust Company
                                       as Guarantee Trustee


                                       By:      /s/ Denise M. Geran
                                             --------------------------------
                                       Name:   Denise M. Geran
                                       Title:  Financial Services Officer


                                      18