<PAGE>   1
                                                                     EXHIBIT 4.4




                                     UBS AG

                                       TO

                    [_____________________________________]
                                     Trustee




                                WARRANT INDENTURE



                            Dated as of [           ]
<PAGE>   2
                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                                        PAGE
                                                                                                                        ----
<S>                                                                                                                     <C>
PARTIES ...........................................................................................................        1
RECITALS OF THE COMPANY ...........................................................................................        1

                                                         ARTICLE ONE

                                   DEFINITIONS AND OTHER PROVISIONS OF GENERAL APPLICATION

SECTION 101. Definitions ..........................................................................................        1
                 Act ..............................................................................................        2
                 Additional Amounts ...............................................................................        2
                 Affiliate ........................................................................................        2
                 Applicable Procedures ............................................................................        2
                 Authenticating Agent .............................................................................        2
                 Authorized Agent .................................................................................        2
                 Authorized Officer ...............................................................................        2
                 Board of Directors ...............................................................................        2
                 Board Resolution .................................................................................        2
                 Business Day .....................................................................................        2
                 Call Warrants ....................................................................................        2
                 Commission .......................................................................................        3
                 Company ..........................................................................................        3
                 Company Request ..................................................................................        3
                 convert, converted, conversion .................................................................        3
                 Corporate Trust Office ...........................................................................        3
                 corporation ......................................................................................        3
                 Depositary .......................................................................................        3
                 Event of Default .................................................................................        3
                 Exchange Act .....................................................................................        3
                 Expiration Date ..................................................................................        3
                 Final Date .......................................................................................        3
                 Global Security ..................................................................................        3
                 Group Executive Board ............................................................................        4
                 Holder ...........................................................................................        4
                 Indenture ........................................................................................        4
                 Investment Company Act ...........................................................................        4
                 Notice of Default ................................................................................        4
                 Officers' Certificate ............................................................................        4
                 Opinion of Counsel ...............................................................................        4
                 Outstanding ......................................................................................        4
                 Paying Agent .....................................................................................        5
                 Payment or Settlement Date .......................................................................        5
                 Person ...........................................................................................        5
                 Place of Payment .................................................................................        5
</TABLE>

NOTE: This table of contents shall not, for any purpose, be deemed to be a part
of this Indenture

                                       -i-
<PAGE>   3
<TABLE>
<S>                                                                                                                     <C>
                 Predecessor Security .............................................................................        5
                 Put Warrants .....................................................................................        5
                 Redemption Date ..................................................................................        5
                 Redemption Price .................................................................................        5
                 Responsible Officer ..............................................................................        5
                 Securities .......................................................................................        6
                 Securities Act ...................................................................................        6
                 Security Register ................................................................................        6
                 Subsidiary .......................................................................................        6
                 Trust Indenture Act ..............................................................................        6
                 Trustee ..........................................................................................        6
                 Vice President ...................................................................................        6
                 Warrants .........................................................................................        6
                 Warrant Property .................................................................................        6
SECTION 102. Compliance Certificates and Opinions .................................................................        6
SECTION 103. Form of Documents Delivered to Trustee ...............................................................        7
SECTION 104. Acts of Holders; Record Dates ........................................................................        8
SECTION 105. Notices, Etc., to Trustee and Company ................................................................        9
SECTION 106. Notice to Holders; Waiver ............................................................................       10
SECTION 107. Conflict with Trust Indenture Act ....................................................................       10
SECTION 108. Effect of Headings and Table of Contents .............................................................       10
SECTION 109. Successors and Assigns ...............................................................................       10
SECTION 110. Separability Clause ..................................................................................       11
SECTION 111. Benefits of Indenture ................................................................................       11
SECTION 112. Characterization of Warrants .........................................................................       11
SECTION 113. Governing Law ........................................................................................       11
SECTION 114. Submission to Jurisdiction; Appointment of Agent for Service of Process ..............................       11
SECTION 115. Legal Holidays .......................................................................................       12

                                                         ARTICLE TWO

                                                       SECURITY FORMS

SECTION 201. Forms Generally ......................................................................................       13
SECTION 202. Form of Face of Call Warrant .........................................................................       13
SECTION 203. Form of Reverse of Call Warrant ......................................................................       16
SECTION 204. Form of Face of Put Warrant ..........................................................................       20
SECTION 205. Form of Reverse of Put Warrant .......................................................................       23
SECTION 206. Form of Legend for Global Securities .................................................................       27
SECTION 207. Form of Trustee's Certificate of Authentication ......................................................       28

                                                        ARTICLE THREE

                                                       THE SECURITIES

SECTION 301. Amount Unlimited; Issuable in Series .................................................................       29
SECTION 302. Denominations ........................................................................................       31
</TABLE>


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<TABLE>
<S>                                                                                                                     <C>
SECTION 303. Execution, Authentication, Delivery and Dating .......................................................       31
SECTION 304. Temporary Securities .................................................................................       33
SECTION 305. Registration, Registration of Transfer and Exchange ..................................................       33
SECTION 306. Mutilated, Destroyed, Lost and Stolen Securities .....................................................       35
SECTION 307. Persons Deemed Owners ................................................................................       36
SECTION 308. Cancellation .........................................................................................       36
SECTION 309. CUSIP Numbers ........................................................................................       37
SECTION 310. Calculation Agent ....................................................................................       37

                                                        ARTICLE FOUR

                                                 SATISFACTION AND DISCHARGE

SECTION 401. Satisfaction and Discharge of Indenture ..............................................................       38
SECTION 402. Application of Trust Money and Warrant Property ......................................................       39

                                                        ARTICLE FIVE

                                                          REMEDIES

SECTION 501. Events of Default ....................................................................................       40
SECTION 502. Collection of Amounts Due and Suits for Enforcement by Trustee .......................................       41
SECTION 503. Trustee May File Proofs of Claim .....................................................................       41
SECTION 504. Trustee May Enforce Claims Without Possession of Securities ..........................................       42
SECTION 505. Application of Money Collected .......................................................................       42
SECTION 506. Limitation on Suits ..................................................................................       42
SECTION 507. Unconditional Right of Holders to Receive Money or Warrant Property Due With Respect to Securities and
             to Exercise  ................................................................................                43
SECTION 508. Restoration of Rights and Remedies ...................................................................       43
SECTION 509. Rights and Remedies Cumulative .......................................................................       43
SECTION 510. Delay or Omission Not Waiver .........................................................................       44
SECTION 511. Control by Holders ...................................................................................       44
SECTION 512. Waiver of Past Defaults ..............................................................................       44
SECTION 513. Undertaking for Costs ................................................................................       44
SECTION 514. Waiver of Usury, Stay or Extension Laws ..............................................................       45

                                                         ARTICLE SIX

                                                         THE TRUSTEE

SECTION 601. Certain Duties and Responsibilities ..................................................................       46
SECTION 602. Notice of Defaults ...................................................................................       46
SECTION 603. Certain Rights of Trustee ............................................................................       46
SECTION 604. Not Responsible for Recitals or Issuance of Securities ...............................................       47
SECTION 605. May Hold Securities ..................................................................................       48
SECTION 606. Money or Warrant Property Held in Trust ..............................................................       48
SECTION 607. Compensation and Reimbursement .......................................................................       48
</TABLE>


                                      -iii-
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<TABLE>
<S>                                                                                                                     <C>
SECTION 608. Conflicting Interests ................................................................................       49
SECTION 609. Corporate Trustee Required; Eligibility ..............................................................       49
SECTION 610. Resignation and Removal; Appointment of Successor ....................................................       49
SECTION 611. Acceptance of Appointment by Successor ...............................................................       51
SECTION 612. Merger, Conversion, Consolidation or Succession to Business ..........................................       52
SECTION 613. Preferential Collection of Claims Against Company ....................................................       52
SECTION 614. Appointment of Authenticating Agent ..................................................................       52

                                                        ARTICLE SEVEN

                                      HOLDERS' LISTS AND REPORTS BY TRUSTEE AND COMPANY

SECTION 701. Company to Furnish Trustee Names and Addresses of Holders ............................................       54
SECTION 702. Preservation of Information; Communications to Holders ...............................................       54
SECTION 703. Reports by Trustee ...................................................................................       54
SECTION 704. Reports by Company ...................................................................................       55

                                                        ARTICLE EIGHT

                                    CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

SECTION 801. Company May Consolidate, Etc., Only on Certain Terms .................................................       56
SECTION 802. Successor Substituted ................................................................................       56

                                                        ARTICLE NINE

                                                   SUPPLEMENTAL INDENTURES

SECTION 901. Supplemental Indentures Without Consent of Holders ...................................................       58
SECTION 902. Supplemental Indentures With Consent of Holders ......................................................       59
SECTION 903. Execution of Supplemental Indentures .................................................................       60
SECTION 904. Effect of Supplemental Indentures ....................................................................       60
SECTION 905. Conformity with Trust Indenture Act ..................................................................       60
SECTION 906. Reference in Securities to Supplemental Indentures ...................................................       60

                                                         ARTICLE TEN

                                                          COVENANTS

SECTION 1001. Payment or Delivery of Money or Warrant Property ....................................................       61
SECTION 1002. Maintenance of Office or Agency .....................................................................       61
SECTION 1003. Money and Warrant Property for Securities Payments and Deliveries to Be Held in Trust ...............       61
SECTION 1004. Statement by Officers as to Default .................................................................       63
SECTION 1005. Existence ...........................................................................................       63
SECTION 1006. Payment of Taxes and Other Claims ...................................................................       63
SECTION 1007. Payment of Additional Amounts .......................................................................       63
SECTION 1008. Waiver of Certain Covenants .........................................................................       64
</TABLE>


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<TABLE>
<S>                                                                                                                     <C>
                                                       ARTICLE ELEVEN

                                                  REDEMPTION OF SECURITIES

SECTION 1101. Applicability of Article ............................................................................       66
SECTION 1102. Election to Redeem; Notice to Trustee ...............................................................       66
SECTION 1103. Selection by Trustee of Securities to Be Redeemed ...................................................       66
SECTION 1104. Notice of Redemption ................................................................................       67
SECTION 1105. Deposit of Redemption Price .........................................................................       67
SECTION 1106. Securities Payable on Redemption Date ...............................................................       68
SECTION 1107. Securities Redeemed in Part .........................................................................       68


TESTIMONIUM .......................................................................................................       62
SIGNATURES AND SEALS ..............................................................................................       62
ACKNOWLEDGMENTS
</TABLE>


                                       -v-
<PAGE>   7
                 CERTAIN SECTIONS OF THIS INDENTURE RELATING TO
                            SECTIONS 310 THROUGH 318,
                 INCLUSIVE, OF THE TRUST INDENTURE ACT OF 1939:

<TABLE>
<CAPTION>
   TRUST INDENTURE
     ACT SECTION                                                                  INDENTURE SECTION
     -----------                                                                  -----------------
<S>                                                                               <C>
Section 310 (a)(1)............................................................     609
            (a)(2)............................................................     609
            (a)(3)............................................................     Not Applicable
            (a)(4)............................................................     Not Applicable
            (b)...............................................................     608
                                                                                   610
Section 311 (a)...............................................................     613
            (b)...............................................................     613
Section 312 (a)...............................................................     701
                                                                                   702
            (b)...............................................................     702
            (c)...............................................................     702
Section 313 (a)...............................................................     703
            (b)...............................................................     703
            (c)...............................................................     703
            (d)...............................................................     703
Section 314 (a)...............................................................     704
            (a)(4)............................................................     101
                                                                                   1004
            (b)...............................................................     Not Applicable
            (c)(1)............................................................     102
            (c)(2)............................................................     102
            (c)(3)............................................................     Not Applicable
            (d)...............................................................     Not Applicable
            (e)...............................................................     102
Section 315 (a)...............................................................     601
            (b)...............................................................     602
            (c)...............................................................     601
            (d)...............................................................     601
            (e)...............................................................     513
Section 316 (a)...............................................................     101
            (a)(1)(A).........................................................     511
            (a)(1)(B).........................................................     512
            (a)(2)............................................................     Not Applicable
            (b)...............................................................     507
            (c)...............................................................     104
Section 317 (a)(1)............................................................     502
            (a)(2)............................................................     503
            (b)...............................................................     1003
Section 318 (a)...............................................................     107
</TABLE>

NOTE: This reconciliation and tie shall not, for any purpose, be deemed to be a
part of the Indenture.

                                      -vi-
<PAGE>   8
         WARRANT INDENTURE, dated as of ____________, between UBS AG, a
corporation duly organized and existing under the laws of Switzerland (herein
called the "Company"), having its principal office at Bahnhofstrasse 45, Zurich,
Switzerland, and [Trustee], as Trustee (herein called the "Trustee").

                             RECITALS OF THE COMPANY

         The Company has duly authorized the execution and delivery of this
Indenture to provide for the issuance from time to time of its Universal
Warrants, as hereinafter defined (herein sometimes called the "Securities"), to
be issued in one or more series as in this Indenture provided.

         All things necessary to make this Indenture a valid agreement of the
Company, in accordance with its terms, have been done.

         NOW, THEREFORE, THIS INDENTURE WITNESSETH:

         For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually agreed, for the equal and
proportionate benefit of all Holders of the Securities or of series thereof, as
follows:

                                  ARTICLE ONE

                        DEFINITIONS AND OTHER PROVISIONS
                             OF GENERAL APPLICATION

SECTION 101. Definitions.

         For all purposes of this Indenture, except as otherwise expressly
provided or unless the context otherwise requires:

                  (1) the terms defined in this Article have the meanings
         assigned to them in this Article and include the plural as well as the
         singular;

                  (2) all other terms used herein which are defined in the Trust
         Indenture Act, either directly or by reference therein, have the
         meanings assigned to them therein;

                  (3) all accounting terms not otherwise defined herein have the
         meanings assigned to them in accordance with generally accepted
         accounting principles, and, except as otherwise herein expressly
         provided, the term "generally accepted accounting principles" with
         respect to any computation required or permitted hereunder shall mean
         such accounting principles as are generally accepted--at the date of
         such computation;

                  (4) unless the context otherwise requires, any reference to an
         "Article" or a "Section" refers to an Article or a Section, as the case
         may be, of this Indenture;

                  (5) the words "herein", "hereof" and "hereunder" and other
         words of similar import refer to this Indenture as a whole and not to
         any particular Article, Section or other subdivision; and

<PAGE>   9
                  (6) when used with respect to any Security, the words
         "exercise" and "exercised" are intended to refer to the right of the
         Holder or the Company to exercise such Security and to receive in
         exchange money, securities or other property in accordance with such
         terms as may hereafter be specified for such Security as contemplated
         by Section 301, and these words are not intended to refer to any right
         of the Holder or the Company to exchange such Security for other
         Securities of the same series and like tenor pursuant to Section 304,
         305, 306 or 906 or another similar provision of this Indenture, unless
         the context otherwise requires; and references herein to the terms of
         any Security that may be exercised mean such terms as may be specified
         for such Security as contemplated in Section 301.

         "Act", when used with respect to any Holder, has the meaning specified
in Section 104.

         "Additional Amounts" has the meaning specified in Section 1007.

         "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. 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, 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.

         "Applicable Procedures" of a Depositary means, with respect to any
matter at any time, the policies and procedures of such Depositary, if any, that
are applicable to such matter at such time.

         "Authenticating Agent" means any Person authorized by the Trustee
pursuant to Section 614 to act on behalf of the Trustee to authenticate
Securities of one or more series.

         "Authorized Agent" has the meaning specified in Section 113.

         "Authorized Officer" means an officer having the title of Chief
Financial Officer, Managing Director, Executive Director or Director of the
Company.

         "Board of Directors" means either the board of directors of the Company
or any duly authorized committee of that board or the Group Executive Board.

         "Board Resolution" means a copy of a resolution certified by the
Secretary or an Assistant Secretary of the Company to have been duly adopted by
the Board of Directors and to be in full force and effect on the date of such
certification, and delivered to the Trustee.

         "Business Day" , when used with respect to any Place of Payment, except
as may otherwise be provided in the form of Securities of any particular series,
means each Monday, Tuesday, Wednesday, Thursday and Friday which is not a day on
which banking institutions in that Place of Payment are authorized or obligated
by law or executive order to close.

         "Call Warrants" has the meaning specified in Section 301(5).


                                      -2-
<PAGE>   10
         "Commission" means the Securities and Exchange Commission, from time to
time constituted, created under the Exchange Act, or, if at any time after the
execution of this instrument such Commission is not existing and performing the
duties now assigned to it under the Trust Indenture Act, then the body
performing such duties at such time.

         "Company" means the Person named as the "Company" in the first
paragraph of this instrument until a successor Person shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Company" shall mean such successor Person.

         "Company Request" or "Company Order" means a written request or order
signed in the name of the Company by any two Authorized Officers, and delivered
to the Trustee from time to time.

          "Convert", "converted" and "conversion," when used with respect to any
Security, are intended to refer to the right of the Holder or the Company to
convert or exchange such security into or for Securities or other property in
accordance with such terms, if any, as may hereafter be specified for such
Security as contemplated by Section 301, and these words are not intended to
refer to any right of the holder or the Company to exchange such Security for
other Securities of the same series and like tenor pursuant to Section 304, 305,
306, 906 or 1107 or another similar provision of this Indenture, unless the
context otherwise requires; and references herein to the terms of any Security
that may be converted mean such terms as may be specified for such Security as
contemplated in Section 301.

         "Corporate Trust Office" means the principal office of the Trustee in
New York, New York at which at any particular time its corporate trust business
shall be administered, which at the date of this Indenture is located at
___________.

         "corporation" means a corporation, association, company, joint-stock
company or business trust.

         "Depositary" means, with respect to Securities of any series issuable
in whole or in part in the form of one or more Global Securities, a clearing
agency [REGISTERED UNDER THE EXCHANGE ACT] that is designated to act as
Depositary for such Securities as contemplated by Section 301.

         "Event of Default" has the meaning specified in Section 501.

         "Exchange Act" means the Securities Exchange Act of 1934 and any
statute successor thereto, in each case as amended from time to time.

         "Expiration Date" , when used with respect to Securities of any series,
means the date on which the right to exercise the Securities of such series
shall expire.

         "Final Date" has the meaning specified in Section 104.

         "Global Security" means a Security that evidences all or part of the
Securities of any series and bears the legend set forth in Section 206 (or such
legend as may be specified as contemplated by Section 301 for such Securities).


                                      -3-
<PAGE>   11
         "Group Executive Board" means the most senior executive body of the
Company, including the Chief Executive Officer and the Chief Financial Officer.

         "Holder" means a Person in whose name a Security is registered in the
Security Register.

         "Indenture" means this instrument as originally executed and as it may
from time to time be supplemented or amended by one or more indentures
supplemental hereto entered into pursuant to the applicable provisions hereof,
including, for all purposes of this instrument and any such supplemental
indenture, the provisions of the Trust Indenture Act that are deemed to be a
part of and govern this instrument and any such supplemental indenture,
respectively. The term "Indenture" shall also include the terms of particular
series of Securities established as contemplated by Section 301.

         "Investment Company Act" means the Investment Company Act of 1940 and
any statute successor thereto, in each case as amended from time to time.

         "Notice of Default" means a written notice of the kind specified in
Section 501(2).

         "Officers' Certificate" means a certificate signed by any two
authorized officers of the Company and delivered to the Trustee. One of the
officers signing an Officers' Certificate given pursuant to Section 1004 shall
be the principal executive, financial or accounting officer of the Company.

         "Opinion of Counsel" means a written opinion of counsel, who may be
counsel for the Company, and who shall be acceptable to the Trustee.

         "Outstanding" , when used with respect to Securities, means, as of the
date of determination, all Securities theretofore authenticated and delivered
under this Indenture, except:

                  (1) Securities theretofore cancelled by the Trustee or
         delivered to the Trustee for cancellation;

                  (2) Securities for whose payment, redemption or settlement
         money or Warrant Property in the necessary amount has been theretofore
         deposited with the Trustee or any Paying Agent (other than the Company)
         in trust or set aside and segregated in trust by the Company (if the
         Company shall act as its own Paying Agent) for the Holders of such
         Securities, provided that, if such Securities are to be redeemed,
         notice of such redemption has been duly given pursuant to this
         Indenture or provision therefor satisfactory to the Trustee has been
         made;

                  (3) Securities which have been paid pursuant to Section 306 or
         in exchange for or in lieu of which other Securities have been
         authenticated and delivered pursuant to this Indenture, other than any
         such Securities in respect of which there shall have been presented to
         the Trustee proof satisfactory to it that such Securities are held by a
         bona fide purchaser in whose hands such Securities are valid
         obligations of the Company; and

                  (4) Securities as to which any money or Warrant Property
         payable or deliverable upon exercise thereof has been paid or delivered
         (or such payment or delivery has been duly provided for), or as to
         which any other particular conditions have been satisfied, in each case
         as may be provided for such Securities as contemplated in Section 301;


                                      -4-
<PAGE>   12
provided, however, that in determining whether the Holders of the requisite
number of Outstanding Warrants have given, made or taken any request, demand,
authorization, direction, notice, consent, waiver or other action hereunder as
of any date, Securities owned by the Company or any other obligor upon the
Securities or any Affiliate of the Company or of such other obligor shall be
disregarded and deemed not to be Outstanding, except that, in determining
whether the Trustee shall be protected in relying upon any such request, demand,
authorization, direction, notice, consent, waiver or other action, only
Securities which the Trustee knows to be so owned shall be so disregarded.
Securities so owned which have been pledged in good faith may be regarded as
Outstanding if the pledgee establishes to the satisfaction of the Trustee the
pledgee's right so to act with respect to such Securities and that the pledgee
is not the Company or any other obligor upon the Securities or any Affiliate of
the Company or of such other obligor.

         "Paying Agent" , when used with respect to the Securities of any
series, means any Person authorized by the Company to pay or deliver any money
or Warrant Property payable or deliverable on behalf of the Company upon
exercise or redemption of such Securities and includes any warrant agent
appointed by the Company with respect to such series.

         "Payment or Settlement Date" , when used with respect to any Security,
means the date when any money or Warrant Property with respect to such Security
becomes payable or deliverable upon exercise or redemption of such Security in
accordance with its terms.

         "Person" means any individual, corporation, partnership, joint venture,
trust, unincorporated organization or government or any agency or political
subdivision thereof.

         "Place of Payment" , when used with respect to the Securities of any
series and subject to Section 1002, means the place or places where any money or
Warrant Property payable or deliverable upon exercise or redemption of such
Securities is payable or deliverable.

         "Predecessor Security" of any particular Security means every previous
Security evidencing all or a portion of the same contractual obligation as that
evidenced by such particular Security; and, for the purposes of this definition,
any Security authenticated and delivered under Section 306 in exchange for or in
lieu of a mutilated, destroyed, lost or stolen Security shall be deemed to
evidence the same contractual obligation as the mutilated, destroyed, lost or
stolen Security.

         "Put Warrants" has the meaning specified in Section 301(5).

         "Redemption Date" , when used with respect to any Security to be
redeemed, means the date fixed for such redemption by or pursuant to this
Indenture.

         "Redemption Price" , when used with respect to any Security to be
redeemed, means the price at which it is to be redeemed pursuant to this
Indenture.


                                      -5-
<PAGE>   13
         "Securities" has the meaning stated in the first recital of this
Indenture and more particularly means any Securities authenticated and delivered
under this Indenture.

         "Securities Act" means the Securities Act of 1933 and any statute
successor thereto, in each case as amended from time to time.

         "Security Register" and "Security Registrar" have the respective
meanings specified in Section 305.

         "Subsidiary" means any Person a majority of the combined voting power
of the total outstanding ownership interests in which is, at the time of
determination, beneficially owned or held, directly or indirectly, by the
Company or by one or more other Subsidiaries, or by the Company and one or more
other Subsidiaries. For the purposes of this definition, "voting power" means
power to vote in an ordinary election of directors (or, in the case of a Person
that is not a corporation, ordinarily to appoint or approve the appointment of
Persons holding similar positions), whether at all times or only so long as no
senior class of ownership interests has such voting power by reason of any
contingency.

         "Trust Indenture Act" means the Trust Indenture Act of 1939 as in force
at the date as of which this instrument was executed; provided, however, that in
the event the Trust Indenture Act of 1939 is amended after such date, "Trust
Indenture Act" means, to the extent required by any such amendment, the Trust
Indenture Act of 1939 as so amended.

         "Trustee" means the Person named as the "Trustee" in the first
paragraph of this instrument until a successor Trustee shall have become such
pursuant to the applicable provisions of this Indenture, and thereafter
"Trustee" shall mean or include each Person who is then a Trustee hereunder, and
if at any time there is more than one such Person, "Trustee" as used with
respect to the Securities of any series shall mean the Trustee with respect to
Securities of that series.

         "Vice President" , when used with respect to the Company or the
Trustee, means any vice president, whether or not designated by a number or a
word or words added before or after the title "vice president".

         "Warrants" or "Universal Warrants" means warrants, issued by the
Company and authenticated and delivered under this Indenture, to purchase or
sell, or whose cash value is determined by reference to or is linked to the
performance, level or value of, one or more of the following: (i) securities of
one or more issuers, including the common or preferred stock or other securities
of the Company or debt or equity securities of third parties, (ii) one or more
currencies, (iii) one or more commodities, (iv) any other financial, economic or
other measure or instrument (including the occurrence or non-occurrence of any
event or circumstance) and/or (v) one or more indices or baskets of the items
described in clauses (i), (ii), (iii) and (iv).

         "Warrant Property" , when used with respect to a Security, means the
property described in clauses (i), (ii), (iii) and (iv) of the definition of
Warrants.

SECTION 102. Compliance Certificates and Opinions.

         Upon any application or request by the Company to the Trustee to take
any action under any provision of this Indenture, the Company shall furnish to
the Trustee such certificates and opinions as

                                      -6-
<PAGE>   14
may be required under the Trust Indenture Act; provided, however, that no such
opinion shall be required in connection with the issuance of Securities of any
Series. Each such certificate or opinion shall be given in the form of an
Officers' Certificate, if to be given by an officer of the Company, or an
Opinion of Counsel, if to be given by counsel, and shall comply with the
requirements of the Trust Indenture Act and any other requirements set forth in
this Indenture.

         Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this Indenture (except for certificates
provided for in Section 1004) shall include,

                  (1) a statement that each individual signing such certificate
         or opinion has read such covenant or condition and the definitions
         herein relating thereto;

                  (2) a brief statement as to the nature and scope of the
         examination or investigation upon which the statements or opinions
         contained in such certificate or opinion are based;

                  (3) a statement that, in the opinion of each such individual,
         he has made such examination or investigation as is necessary to enable
         him 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 such
         individual, such condition or covenant has been complied with.

SECTION 103. Form of Documents Delivered to Trustee.

         In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to such matters in one or several documents.

         Any certificate or opinion of an officer of the Company may be based,
insofar as it relates to legal matters, upon a certificate or opinion of, or
representation by, counsel, unless such officer knows, or in the exercise of
reasonable care should know, that the certificate or opinion or representations
with respect to the matters upon which his certificate or opinion is based are
erroneous. Any such certificate or opinion of counsel may be based, insofar as
it relates to factual matters, upon a certificate or opinion of, or
representations by, an officer or officers of the Company stating that the
information with respect to such factual matters is in the possession of the
Company, unless such counsel knows, or in the exercise of reasonable care should
know, that the certificate or opinion or representations with respect to such
matters are erroneous.

         Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other
instruments under this Indenture, they may, but need not, be consolidated and
form one instrument.


                                      -7-

<PAGE>   15
SECTION 104. Acts of Holders; Record Dates.

         Any request, demand, authorization, direction, notice, consent, waiver
or other action provided or permitted by this Indenture to be given, made or
taken by Holders may be embodied in and evidenced by one or more instruments of
substantially similar tenor signed by such Holders in person or by agent duly
appointed in writing; and, except as herein otherwise expressly provided, such
action shall become effective when such instrument or instruments are delivered
to the Trustee and, where it is hereby expressly required, to the Company. Such
instrument or instruments (and the action embodied therein and evidenced
thereby) are herein sometimes referred to as the "Act" of the Holders signing
such instrument or instruments. Proof of execution of any such instrument or of
a writing appointing any such agent shall be sufficient for any purpose of this
Indenture and (subject to Section 601) conclusive in favor of the Trustee and
the Company, if made in the manner provided in this Section.

         The fact and date of the execution by any Person of any such instrument
or writing may be proved by the affidavit of a witness of such execution or by a
certificate of a notary public or other officer authorized by law to take
acknowledgments of deeds, certifying that the individual signing such instrument
or writing acknowledged to him the execution thereof. Where such execution is by
a signer acting in a capacity other than his individual capacity, such
certificate or affidavit shall also constitute sufficient proof of his
authority. The fact and date of the execution of any such instrument or writing,
or the authority of the Person executing the same, may also be proved in any
other manner which the Trustee deems sufficient.

         The ownership of Securities shall be proved by the Security Register.

         Any request, demand, authorization, direction, notice, consent, waiver
or other Act of the Holder of any Security shall bind every future Holder of the
same Security and the Holder of every Security issued upon the registration of
transfer thereof or in exchange therefor or in lieu thereof in respect of
anything done, omitted or suffered to be done by the Trustee or the Company in
reliance thereon, whether or not notation of such action is made upon such
Security.

         The Company may set any day as a record date for the purpose of
determining the Holders of Outstanding Securities of any series entitled to
give, make or take any request, demand, authorization, direction, notice,
consent, waiver or other action provided or permitted by this Indenture to be
given, made or taken by Holders of Securities of such series, provided that the
Company may not set a record date for, and the provisions of this paragraph
shall not apply with respect to, the giving or making of any notice,
declaration, request or direction referred to in the next paragraph. If any
record date is set pursuant to this paragraph, the Holders of Outstanding
Securities of the relevant series on such record date, and no other Holders,
shall be entitled to take the relevant action, whether or not such Holders
remain Holders after such record date; provided that no such action shall be
effective hereunder unless taken on or prior to the applicable Final Date by
Holders of the requisite number of Outstanding Warrants of such series on such
record date. Nothing in this paragraph shall be construed to prevent the Company
from setting a new record date for any action for which a record date has
previously been set pursuant to this paragraph (whereupon the record date
previously set shall automatically and with no action by any Person be cancelled
and of no effect), and nothing in this paragraph shall be construed to render
ineffective any action taken by Holders of the requisite number of Outstanding
Warrants of the relevant series on the date such action is taken. Promptly after
any record date is set pursuant to this paragraph, the Company, at its own
expense, shall cause notice of such record date, the proposed action

                                      -8-
<PAGE>   16
by Holders and the applicable Final Date to be given to the Trustee in writing
and to each Holder of Securities of the relevant series in the manner set forth
in Section 106.

         The Trustee may set any day as a record date for the purpose of
determining the Holders of Outstanding Securities of any series entitled to join
in the giving or making of (i) any Notice of Default, (ii) any request to
institute proceedings referred to in Section 506(2) or (iii) any direction
referred to in Section 511, in each case with respect to Securities of such
series. If any record date is set pursuant to this paragraph, the Holders of
Outstanding Securities of such series on such record date, and no other Holders,
shall be entitled to join in such notice, declaration, request or direction,
whether or not such Holders remain Holders after such record date; provided that
no such action shall be effective hereunder unless taken on or prior to the
applicable Final Date by Holders of the requisite number of Outstanding Warrants
of such series on such record date. Nothing in this paragraph shall be construed
to prevent the Trustee from setting a new record date for any action for which a
record date has previously been set pursuant to this paragraph (whereupon the
record date previously set shall automatically and with no action by any Person
be cancelled and of no effect), and nothing in this paragraph shall be construed
to render ineffective any action taken by Holders of the requisite number of
Outstanding Warrants of the relevant series on the date such action is taken.
Promptly after any record date is set pursuant to this paragraph, the Trustee,
at the Company's expense, shall cause notice of such record date, the proposed
action by Holders and the applicable Final Date to be given to the Company in
writing and to each Holder of Securities of the relevant series in the manner
set forth in Section 106.

         With respect to any record date set pursuant to this Section, the party
hereto that sets such record dates may designate any day as the "Final Date" and
from time to time may change the Final Date to any earlier or later day;
provided that no such change shall be effective unless notice of the proposed
new Final Date is given to the other party hereto in writing, and to each Holder
of Securities of the relevant series in the manner set forth in Section 106, on
or prior to the existing Final Date. If a Final Date is not designated with
respect to any record date set pursuant to this Section, the party hereto that
set such record date shall be deemed to have initially designated the 180th day
after such record date as the Final Date with respect thereto, subject to its
right to change the Final Date as provided in this paragraph. Notwithstanding
the foregoing, no Final Date shall be later than the 180th day after the
applicable record date.

         Without limiting the foregoing, a Holder entitled hereunder to take any
action hereunder with regard to any particular Warrants may do so with regard to
all or any lesser number of such Warrants or by one or more duly appointed
agents each of which may do so pursuant to such appointment with regard to all
or any lesser number of such Warrants.

Section 105. Notices, Etc., to Trustee and Company.

         Any request, demand, authorization, direction, notice, consent, waiver
or Act of Holders or other document provided or permitted by this Indenture to
be made upon, given or furnished to, or filed with,

                  (1) the Trustee by any Holder or by the Company shall be
         sufficient for every purpose hereunder if made, given, furnished or
         filed in writing to or with the Trustee and received at its Corporate
         Trust Office, or

                  (2) the Company by the Trustee or by any Holder shall be
         sufficient for every purpose

                                      -9-
<PAGE>   17
         hereunder (unless otherwise herein expressly provided) if in writing
         and mailed, first-class postage prepaid, to the Company addressed to it
         at UBS AG, Structured Derivative Products, 677 Washington Blvd.,
         Stamford, CT, 06901, Attn: Mark Ritter, with a copy to Legal and
         External Affairs, 677 Washington Blvd., Stamford, CT, 06901, Attn:
         Equities Group, or at any other address previously furnished in writing
         to the Trustee by the Company.

SECTION 106. Notice to Holders; Waiver.

         Where this Indenture provides for notice to Holders of any event, such
notice shall be sufficiently given (unless otherwise herein expressly provided)
if in writing and mailed, first-class postage prepaid, to each Holder affected
by such event, at his address as it appears in the Security Register, not later
than the latest date (if any), and not earlier than the earliest date (if any),
prescribed for the giving of such notice. In any case where notice to Holders is
given by mail, neither the failure to mail such notice, nor any defect in any
notice so mailed, to any particular Holder shall affect the sufficiency of such
notice with respect to other Holders. Where this Indenture provides for notice
in any manner, such notice may be waived in writing by the Person entitled to
receive such notice, either before or after the event, and such waiver shall be
the equivalent of such notice. Waivers of notice by Holders shall be filed with
the Trustee, but such filing shall not be a condition precedent to the validity
of any action taken in reliance upon such waiver.

         In case by reason of the suspension of regular mail service or by
reason of any other cause it shall be impracticable to give such notice by mail,
then such notification as shall be made with the approval of the Trustee shall
constitute a sufficient notification for every purpose hereunder.

         Where this Indenture provides for Notice of any event to a Holder of a
Global Security, such notice shall be sufficiently given if given to the
Depositary for such Security (or its designee), pursuant to its Applicable
Procedures, not later than the latest date (if any), and not earlier than the
earliest date (if any), prescribed for the giving of such notice.

Section 107. Conflict with Trust Indenture Act.

         If any provision hereof limits, qualifies or conflicts with a provision
of the Trust Indenture Act which is required under such Act to be a part of and
govern this Indenture, the latter provision shall control. If any provision of
this Indenture modifies or excludes any provision of the Trust Indenture Act
which may be so modified or excluded, the latter provision shall be deemed to
apply to this Indenture as so modified or to be excluded, as the case may be.

Section 108. Effect of Headings and Table of Contents.

         The Article and Section headings herein and the Table of Contents are
for convenience only and shall not affect the construction hereof.

Section 109. Successors and Assigns.

         All covenants and agreements in this Indenture by the Company shall
bind its successors and assigns, whether so expressed or not.



                                      -10-
<PAGE>   18
SECTION 110. Separability Clause.

         In case any provision in this Indenture or in the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 111. Benefits of Indenture.

         Nothing in this Indenture or in the Securities, express or implied,
shall give to any Person, other than the parties hereto and their successors
hereunder and the Holders, any benefit or any legal or equitable right, remedy
or claim under this Indenture.

SECTION 112. Characterization of Warrants.

         By executing this Indenture, the Company intends that the
characterization, for accounting and other purposes, of the Universal Warrants
as indebtedness or debt for borrowed money, or as any other type of obligation
which is not indebtedness or debt for borrowed money, shall not be affected
solely by the fact that the Universal Warrants have been issued under an
indenture, as opposed to any other instrument, or solely as a result of any of
the terms and definitions used hereunder with respect to Universal Warrants.

SECTION 113. Governing Law.

         This Indenture and the Securities shall be governed by and construed in
accordance with the law of the State of New York.

SECTION 114. Submission to Jurisdiction; Appointment of Agent for Service of
Process.

         The Company hereby appoints Robert C. Dinerstein, acting through its
office at 299 Park Avenue, New York, New York 10171 (or such other address in
the Borough of Manhattan, The City of New York, as such agent shall furnish in
writing to the Trustee) as its authorized agent (the "Authorized Agent") upon
which process may be served in any legal action or proceeding against it with
respect to its obligations under this Indenture or the Securities of any series,
as the case may be, instituted in any federal or state court in the Borough of
Manhattan, The City of New York by the Holder of any Security, and agrees that
service of process upon the Authorized Agent, together with written notice of
said service mailed or delivered to the Company, addressed as provided in
Section 105, shall be deemed in every respect effective service of process upon
the Company in any such legal action or proceeding, and the Company hereby
irrevocably submits to the non-exclusive jurisdiction of any such court in
respect of any such legal action or proceeding and waives, to the extent it may
effectively do so, any objection it may have to the laying of the venue of any
such legal action or proceeding. Such appointment shall be irrevocable so long
as the Holders of Securities shall have any rights pursuant to the terms of the
Securities or of this Indenture until the appointment of a successor Authorized
Agent by the Company and such successor's acceptance of such appointment. The
Company reserves the right to appoint another person located, or with an office,
in the Borough of Manhattan, The City of New York, selected in its sole
discretion, as a successor Authorized Agent, and upon acceptance of such
appointment by such a successor the appointment of the prior Authorized Agent
shall terminate. If for any reason the Robert C. Dinerstein ceases to be able to
act as the Authorized Agent or to have an address in the Borough of Manhattan,
The City of New York, the Company will appoint a successor

                                      -11-
<PAGE>   19
Authorized Agent in accordance with the preceding sentence. The Company further
agrees to take any and all action, including the filing of any and all documents
and instruments as may be necessary to continue such designation and appointment
of such agent or successor in full force and effect for as long as required
hereunder.

SECTION 115. Legal Holidays.

         In any case where the Payment or Settlement Date or Redemption Date of
any Security, or any date on which a Holder of any Security has the right to
exercise such Security, shall not be a Business Day at any Place of Payment,
then (notwithstanding any other provision of this Indenture or of the Securities
(other than a provision of any Security which specifically states that such
provision shall apply in lieu of this Section)) payment or delivery of any money
or Warrant Property payable or deliverable with respect to such Security, or
exercise of such Security, need not be made at such Place of Payment on such
date, but may be made on the next succeeding Business Day at such Place of
Payment with the same force and effect as if made on the Payment or Settlement
Date or Redemption Date, or on such date for exercise, as the case may be.



                                      -12-
<PAGE>   20
                                  ARTICLE TWO

                                 SECURITY FORMS

SECTION 201. Forms Generally.

         The Securities of each series shall be in substantially the form set
forth in this Article, or in such other form as shall be established by or
pursuant to a Board Resolution or in one or more indentures supplemental hereto,
in each case with such appropriate insertions, omissions, substitutions and
other variations as are required or permitted by this Indenture, and may have
such letters, numbers or other marks of identification and such legends or
endorsements placed thereon as may be required to comply with the rules of any
securities exchange or Depositary therefor or as may, consistently herewith, be
determined by the officers executing such Securities, as evidenced by their
execution thereof. If the form of Securities of any series is established by
action taken pursuant to a Board Resolution, a copy of an appropriate record of
such action shall be certified by the Secretary or an Assistant Secretary of the
Company and delivered to the Trustee at or prior to the delivery of the Company
Order contemplated by Section 303 for the authentication and delivery of such
Securities.

         The definitive Securities shall be printed, lithographed or engraved on
steel engraved borders or may be produced in any other manner, all as determined
by the officers executing such Securities, as evidenced by their execution of
such Securities.

SECTION 202. Form of Face of Call Warrant.

         [Insert any legend required by the Internal Revenue Code and the
regulations thereunder.]

         By your purchase or other acquisition of the Warrants, you will be
deemed to represent by acquiring and holding the Warrants that either (i) or
(ii) is true:

         (i)      the funds that you are using to acquire the Warrants are not
                  the assets of an employee benefit or other plan subject to
                  Title I of the Employee Retirement Income Security Act of
                  1974, as amended ("ERISA"), a plan described in Section 4975
                  of the Internal Revenue Code of 1986, as amended (the "Code"),
                  an entity whose underlying assets include "plan assets" by
                  reason of Department of Labor regulation section 2510.3-101 or
                  otherwise, or a governmental plan that is subject to any
                  federal, state or local law that is substantially similar to
                  the provisions of Section 406 of ERISA or Section 4975 of the
                  Code; or

         (ii)     the purchase, holding and disposition of the Warrants and
                  exercise of any rights related thereto will not result in a
                  prohibited transaction under Section 406 of ERISA or Section
                  4975 of the Code (or in the case of a governmental plan, any
                  federal, state or local provision that is substantially
                  similar to Section 406 of ERISA or Section 4975 of the Code).


                                      -13-
<PAGE>   21
                                     UBS AG

                               ------------------

No.________                                  CUSIP No.________________

NUMBER OF WARRANTS EVIDENCED BY THIS CERTIFICATE: [If Security is a Global
Security, insert-- UP TO]

WARRANT PROPERTY:

AMOUNT OF WARRANT PROPERTY
PURCHASABLE PER WARRANT:

EXERCISE PRICE PER WARRANT:

FORM OF PAYMENT OF
EXERCISE PRICE:

FORM OF SETTLEMENT:

DATES OF EXERCISE:

OTHER TERMS:

         This certificate certifies that , or registered assigns, is the Holder
of the number of [Designation of Universal Warrants][If Security is not a Global
Security, insert -- specified above] [If Security is a Global Security, insert
-- specified on Schedule A hereto]. Upon receipt by the Trustee of this
certificate, the exercise notice on the reverse hereof (or an exercise notice in
substantially identical form delivered herewith) (the "Exercise Notice"), duly
completed and executed, and the Exercise Price per Warrant set forth above, in
the form set forth above, for each Warrant to be exercised (the "Exercise
Property") at the Place of Payment, each Warrant evidenced hereby entitles the
Holder hereof to receive, subject to the terms and conditions set forth herein
and in the Indenture referred to below, from UBS AG, a corporation duly
organized and existing under the laws of Switzerland (herein called the
"Company", which term includes any successor Person under the Indenture), the
amount and form of property (the "Warrant Property") or money specified above.
Warrants will not entitle the Holders thereof to any of the rights of the
holders of any of the Warrant Property.

         Any payments of money due on this Security will be made at the office
or agency of the Company maintained for that purpose in New York, New York, in
such coin or currency of the United States of America as at the time of payment
is legal tender for payment of public and private debts, against surrender of
this Security in the case of any payment due on the Payment or Settlement Date;
provided that if this Security is a Global Security, payment may be made
pursuant to the Applicable Procedures of the Depositary as permitted in said
Indenture.

         Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.


                                      -14-
<PAGE>   22
         Unless the certificate of authentication hereon has been executed by
the Trustee referred to on the reverse hereof by manual signature, this Security
shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

Dated:____________

                                   UBS AG

                                   By ____________________________


                                   By ____________________________




                                      -15-
<PAGE>   23
SECTION 203. Form of Reverse of Call Warrant.

         [This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities"), issued and to be issued in one or more
series under an Indenture, dated as of ............, 20.. (herein called the
"Indenture", which term shall have the meaning assigned to it in such
instrument), between the Company and [Trustee] (herein called the "Trustee",
which term includes any successor trustee under the Indenture), and reference is
hereby made to the Indenture for a statement of the respective rights,
limitations of rights, duties and immunities thereunder of the Company, the
Trustee and the Holders of the Securities and of the terms upon which the
Securities are, and are to be, authenticated and delivered. This Security is one
of the series designated on the face hereof [if applicable, insert -- , limited
in number to . . . . . . . Warrants].

         [If applicable, insert-- The Securities of this series are subject to
redemption upon not less than days' nor more than days' notice, at any time [if
applicable, insert-- on or after ............, 20..], as a whole or in part, at
the election of the Company, at the following redemption prices:]

         The Warrants are unsecured contractual obligations of the Company and
rank pari passu with the Company's other unsecured contractual obligations and
with the Company's unsecured and unsubordinated debt.

         Subject to the provisions hereof and the Indenture, all or any of the
Warrants evidenced by this certificate may be exercised on any of the dates of
exercise set forth on the face hereof by delivering or causing to be delivered
this Security (in accordance with the Applicable Procedures of the Depositary,
if this Security is a Global Security), the Exercise Notice, duly completed and
executed, and the Exercise Property for each such Warrant to the Corporate Trust
Office, in the Borough of Manhattan, The City of New York, which is, on the date
hereof [________________], or at such other address as the Trustee may specify
from time to time, with a copy of the Exercise Notice, duly completed and
executed, to the Calculation Agent, ..........., Attention:

         Each Warrant entitles the Holder thereof to receive, upon exercise, the
Warrant Property or money set forth on the face hereof.

         [If the Security is subject to redemption of any kind, insert -- In the
event of redemption of this Security in part only, a new Security or Securities
of this series for the unredeemed portion hereof will be issued in the name of
the Holder hereof upon the cancellation hereof.]

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities of each series to be
affected under the Indenture at any time by the Company and the Trustee with the
consent of the Holders of a majority in number of the Warrants at the time
Outstanding of all series to be affected (considered together as one class for
this purpose). The Indenture also contains provisions (i) permitting the Holders
of a majority in number of the Warrants at the time Outstanding of all series to
be affected under the Indenture (considered together as one class for this
purpose), on behalf of the Holders of all Warrants of such series, to waive
compliance by the Company with certain provisions of the Indenture and (ii)
permitting the Holders of a majority in number of the Warrants at the time
Outstanding of any series to be affected under the Indenture (with each such
series considered

                                      -16-
<PAGE>   24
separately for this purpose), on behalf of the Holders of all Warrants of such
series, to waive certain past defaults under the Indenture and their
consequences. Any such consent or waiver by the Holder of this Security shall be
conclusive and binding upon such Holder and upon all future Holders of this
Security and of any Security issued upon the registration of transfer hereof or
in exchange herefor or in lieu hereof, whether or not notation of such consent
or waiver is made upon this Security.

         No reference herein to the Indenture and no provision of this Security
or of the Indenture shall alter or impair the obligation of the Company, which
is absolute and unconditional, to pay or deliver the money or Warrant Property
due with respect to this Security at the time and place herein prescribed.

         As provided in the Indenture and subject to certain limitations therein
set forth, the transfer of this Security is registrable in the Security
Register, upon surrender of this Security for registration of transfer at the
office or agency of the Company in any Place of Payment with respect to this
Security, duly endorsed by, or accompanied by a written instrument of transfer
in form satisfactory to the Company and the Security Registrar duly executed by,
the Holder hereof or his attorney duly authorized in writing, and thereupon one
or more new Securities of this series and of like tenor, of authorized
denominations and for the same number of Warrants, will be issued to the
designated transferee or transferees.

         The Securities of this series are issuable only in registered form in
denominations of _______ Warrants and any multiple thereof. As provided in the
Indenture and subject to certain limitations therein set forth, Securities of
this series are exchangeable for a like number of Warrants of this series and of
like tenor of a different authorized denomination, as requested by the Holder
surrendering the same.

         No service charge shall be made for any such registration of transfer
or exchange, but the Company may require payment of a sum sufficient to cover
any tax or other governmental charge payable in connection therewith.

         Prior to due presentment of this Security for registration of transfer,
the Company, the Trustee and any agent of the Company or the Trustee may treat
the Person in whose name this Security is registered as the owner hereof for all
purposes, whether or not any payment or delivery of money or Warrant Property
with respect to this Security be overdue, and neither the Company, the Trustee
nor any such agent shall be affected by notice to the contrary.

         This Security is a Global Security and is subject to the provisions of
the Indenture relating to Global Securities, including the limitations in
Section 305 thereof on transfers and exchanges of Global Securities.

         This Security and the Indenture shall be governed by and construed in
accordance with the laws of the State of New York.

         All terms used in this Security which are defined in the Indenture
shall have the meanings assigned to them in the Indenture.


                                      -17-
<PAGE>   25
                       [Designation of Universal Warrants]

                                 Exercise Notice

[Trustee]
[address]
Attn:    [name]                    Tel.:    [number]
         [name]                    Tel.:    [number]
         Fax:                               [number]

with a copy to:

[Insert name and address of Calculation Agent]
Attn:                              Tel.:
                                   Tel.:
         Fax:

Re: Call Warrants on............expiring............, 20.., issued by UBS AG and
described in the prospectus supplement dated............to the prospectus
dated............, 20..

Ladies and Gentlemen:

         The undersigned is, or is acting on behalf of, the beneficial owner of
such number of the Warrants referenced above as is specified at the end of this
Exercise Notice. The undersigned hereby irrevocably elects to exercise such
number of Warrants. The exercise is to be effective on the Business Day on which
the Trustee has received this Exercise Notice, together with all other items
required to be delivered on exercise, and the Calculation Agent has received a
copy of this Exercise Notice, unless all required items have not been received
by 11:00 A.M., New York City time, on that Business Day, in which case the
exercise will be effective as of the next Business Day. We understand, however,
that no exercise shall be effective unless it is effective, as provided above,
no later than the Business Day before the Expiration Date. The effective date
will be the exercise notice date.

         If the Warrants to be exercised are in global form, the undersigned is
delivering this exercise notice to the Trustee and to the Calculation Agent, in
each case by facsimile transmission to the relevant number stated above, or such
other number as the Trustee or Calculation Agent may have designated for this
purpose to the Holder. [If applicable, insert -- In addition, the cash amount
equal to the strike value times the number of Warrants indicated below and the
beneficial interest in the number of Warrants indicated below are being
transferred on the books of the Depositary to an account of the Trustee at the
Depositary.]

         If the Warrants to be exercised are not in global form, the undersigned
or the beneficial owner is the Holder of the Warrants and is delivering this
Exercise Notice to the Trustee and to the Calculation Agent by facsimile
transmission as described above. [If applicable, insert -- In addition, the cash
amount equal to the strike value times the number of Warrants indicated below
and the certificate representing the Warrant are being delivered to the
Trustee.]


                                      -18-
<PAGE>   26
         If the undersigned is not the beneficial owner of the Warrant to be
exercised, the undersigned hereby represents that it has been duly authorized by
the beneficial owner to act on behalf of the beneficial owner.

         Terms used and not defined in this notice have the meanings given to
them in the Warrant or the Indenture specified in the Warrant. The exercise of
the Warrant will be governed by the terms of the Warrant and the Indenture.

         The Calculation Agent should note receipt of the copy of this Exercise
Notice, in the place provided below, on the Business Day of receipt, noting the
date and time of receipt. The consideration to be delivered or paid in the
requested exercise should be made on the [fifth] Business Day after the exercise
notice date in accordance with the terms of the Warrant.

         Number of Warrants to be exercised:

(must be a number greater than or equal to )

Means of Payment of Settlement Value:.

                                   Very truly yours,

                                   -----------------------------------

                                   (Name of beneficial owner or Person
                                   authorized to act on its behalf)

                                   -----------------------------------
                                   (Title)

                                   -----------------------------------
                                   (Telephone No.)

                                   -----------------------------------
                                   (Fax No.)

Receipt of the above exercise notice
is hereby noted:

         , as Calculation Agent

By:
   ------------------------

---------------------------
(Title)

Date and time of receipt:

--------------------------
(Date)

---------------------------
(Time)




                                      -19-
<PAGE>   27
[If Security is a Global Security, insert this Schedule A.]

                                                                      SCHEDULE A



                       [DESIGNATION OF UNIVERSAL WARRANTS]

                                     GLOBAL
                                UNIVERSAL WARRANT
                       SCHEDULE OF EXCHANGES OR EXERCISES

         The initial number of Universal Warrants represented by this Global
Security is In accordance with the Indenture dated as of ................, 20..,
as amended or supplemented, between the Company and [Trustee], as Trustee, the
following (A) exchanges of [the number of Universal Warrants previously
represented hereby and indicated below for a like number of Universal Warrants
represented by a Global Security that has been separated from a Unit (a
"Separated Universal Warrant")](1) [the number of Universal Warrants previously
represented by a Global Security that is part of a Unit (an "Attached Unit
Universal Warrant") and indicated below for a like number of Universal Warrants
represented by this Global Security](2) or (B) reductions in the number of
Universal Warrants represented hereby as a result of the exercise of the number
of such Warrants indicated below have been made:

<TABLE>
<CAPTION>
  Date of      [Number          [Reduced        [Number of        [Increased        Number of          Reduced     Notation
 Exchange     Exchanged          Number          Attached           Number          Universal          Number     Made by or
or Exercise      for           Outstanding         Unit           Outstanding       Warrants         Outstanding   on Behalf
              Separated         Following        Universal         Following        Exercised         Following   of Trustee
              Universal           Such           Warrants            Such                               Such
            Warrants](1)      Exchange](1)       Exchanged       Exchange](2)                         Exercise
                                               for Universal
                                                 Warrants
                                                represented
                                                  by this
                                                 Separated
                                                 Universal
                                                Warrant](2)
<S>         <C>               <C>              <C>               <C>                <C>              <C>          <C>
</TABLE>

(1)      Applies only if this Global Security is part of a Unit.

(2)      Applies only if this Global Security has been separated from a Unit.

Section 204. Form of Face of Put Warrant.

         [Insert any legend required by the Internal Revenue Code and the
regulations thereunder.]

         By your purchase or other acquisition of the Warrants, you will be
deemed to represent by acquiring and holding the Warrants that either (i) or
(ii) is true:

         (i)      the funds that you are using to acquire the Warrants are not
                  the assets of an employee benefit or other plan subject to
                  Title I of the Employee Retirement Income Security Act

                                      -20-
<PAGE>   28
                  of 1974, as amended ("ERISA"), a plan described in Section
                  4975 of the Internal Revenue Code of 1986, as amended (the
                  "Code"), an entity whose underlying assets include "plan
                  assets" by reason of Department of Labor regulation section
                  2510.3-101 or otherwise, or a governmental plan that is
                  subject to any federal, state or local law that is
                  substantially similar to the provisions of Section 406 of
                  ERISA or Section 4975 of the Code; or

         (ii)     the purchase, holding and disposition of the Warrants and
                  exercise of any rights related thereto will not result in a
                  prohibited transaction under Section 406 of ERISA or Section
                  4975 of the Code (or in the case of a governmental plan, any
                  federal, state or local provision that is substantially
                  similar to Section 406 of ERISA or Section 4975 of the Code).

                                     UBS AG

No __________                                CUSIP No._________________

NUMBER OF WARRANTS EVIDENCED BY THIS CERTIFICATE: [If Security is a Global
Security, insert-- UP TO]

CASH SETTLEMENT VALUE PER WARRANT
(OR METHOD OF DETERMINING SAME):

WARRANT PROPERTY:

AMOUNT OF WARRANT PROPERTY DELIVERABLE BY HOLDER UPON EXERCISE PER WARRANT:

PUT PRICE FOR SUCH SPECIFIED AMOUNT OF WARRANT PROPERTY PER WARRANT:

METHOD OF DELIVERY OF ANY WARRANT PROPERTY TO BE DELIVERED FOR SALE UPON
EXERCISE OF WARRANTS:

DATES OF EXERCISE:

OTHER TERMS:

         This certificate certifies that , or registered assigns, is the Holder
of the number of [Designation of Universal Warrants] [If Security is not a
Global Security, insert -- specified above] [If Security is a Global Security,
insert -- specified on Schedule A hereto]. Upon receipt by the Trustee of this
certificate, the exercise notice on the reverse hereof (or an exercise notice in
substantially identical form delivered herewith) (the "Exercise Notice"), duly
completed and executed, and the amount, if any, of Warrant Property saleable per
Warrant set forth above, adjusted, if applicable, as set forth above, for each
Warrant to be exercised, delivered as set forth above at the Place of Payment,
each Warrant evidenced hereby entitles the Holder hereof to receive, subject to
the terms and conditions set forth herein and in the Indenture referred to
below, from UBS AG, a corporation duly organized and existing under the laws of
Switzerland (herein called the "Company", which term includes any successor
Person under the Indenture), the [Cash Settlement Value][Put Price] per Warrant
specified above.


                                      -21-
<PAGE>   29
         Unless otherwise indicated above, a Warrant will not require or entitle
a Holder thereof to sell or deliver to the Company, nor will the Company be
under any obligation to, nor will it, purchase or take delivery from any Holder
of, any Warrant Property, and upon exercise of a Warrant, the Company will make
only a cash payment in the amount of the [Cash Settlement Value][Put Price] per
Warrant. Holders of Warrants will not receive any interest on any [Cash
Settlement Value][Put Price].

         Any payments of money due on this Security will be made at the office
or agency of the Company maintained for that purpose in New York, New York, in
such coin or currency of the United States of America as at the time of payment
is legal tender for payment of public and private debts, against surrender of
this Security in the case of any payment due on the Payment or Settlement Date;
provided that if this Security is a Global Security, payment may be made
pursuant to the Applicable Procedures of the Depositary as permitted in said
Indenture.

         Reference is hereby made to the further provisions of this Security set
forth on the reverse hereof, which further provisions shall for all purposes
have the same effect as if set forth at this place.

         Unless the certificate of authentication hereon has been executed by
the Trustee referred to on the reverse hereof by manual signature, this Security
shall not be entitled to any benefit under the Indenture or be valid or
obligatory for any purpose.

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

Dated:______________________

                                   UBS AG

                                   By ______________________________


                                   By ______________________________



                                      -22-
<PAGE>   30
SECTION 205. Form of Reverse of Put Warrant.

         This Security is one of a duly authorized issue of securities of the
Company (herein called the "Securities"), issued and to be issued in one or more
series under an Indenture, dated as of ..................., 20.. (herein called
the "Indenture", which term shall have the meaning assigned to it in such
instrument), between the Company and [Trustee], as Trustee (herein called the
"Trustee", which term includes any successor trustee under the Indenture), and
reference is hereby made to the Indenture for a statement of the respective
rights, limitations of rights, duties and immunities thereunder of the Company,
the Trustee and the Holders of the Securities and of the terms upon which the
Securities are, and are to be, authenticated and delivered. This Security is one
of the series designated on the face hereof [If applicable, insert -- , limited
in number to.......... Warrants].

         [If applicable, insert-- The Securities of this series are subject to
redemption upon not less than days' nor more than days' notice, at any time [if
applicable, insert-- on or after ............, 20..], as a whole or in part, at
the election of the Company, at the following redemption prices:]

         The Warrants are unsecured contractual obligations of the Company and
rank pari passu with the Company's other unsecured contractual obligations and
with the Company's unsecured and unsubordinated debt.

         Subject to the provisions hereof and the Indenture, all or any of the
Warrants evidenced by this certificate may be exercised on any of the dates of
exercise set forth on the face hereof by delivering or causing to be delivered
this Security (in accordance with the Applicable Procedures of the Depositary,
if this Security is a Global Security), the Exercise Notice, duly completed and
executed, and, if specified on the face hereof, the Exercise Property for each
such Warrant to the Corporate Trust Office, in the Borough of Manhattan, The
City of New York, which is, on the date hereof (unless otherwise specified
herein), [_____________________________________], or at such other address as
the Trustee may specify from time to time, with a copy to the Calculation Agent,
 ............, Attention: .............

         Each Warrant entitles the Holder thereof to receive, upon exercise, the
money set forth on the face hereof.

         [If the Security is subject to redemption of any kind, insert -- In the
event of redemption of this Security in part only, a new Security or Securities
of this series for the unredeemed portion hereof will be issued in the name of
the Holder hereof upon the cancellation hereof.]

         The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities of each series to be
affected under the Indenture at any time by the Company and the Trustee with the
consent of the Holders of a majority in number of the Warrants at the time
Outstanding of all series to be affected (considered together as one class for
this purpose). The Indenture also contains provisions (i) permitting the Holders
of a majority in number of the Warrants at the time Outstanding of all series to
be affected under the Indenture (considered together as one class for this
purpose), on behalf of the Holders of all Warrants of such series, to waive
compliance by the Company with certain provisions of the Indenture and (ii)
permitting the Holders of a majority in number of the Warrants at the time
Outstanding of any series to be affected under the Indenture (with each such
series considered

                                      -23-
<PAGE>   31
separately for this purpose), on behalf of the Holders of all Warrants of such
series, to waive certain past defaults under the Indenture and their
consequences. Any such consent or waiver by the Holder of this Security shall be
conclusive and binding upon such Holder and upon all future Holders of this
Security and of any Security issued upon the registration of transfer hereof or
in exchange herefor or in lieu hereof, whether or not notation of such consent
or waiver is made upon this Security.

         No reference herein to the Indenture and no provision of this Security
or of the Indenture shall alter or impair the obligation of the Company, which
is absolute and unconditional, to pay or deliver the money or Warrant Property
due with respect to this Security at the time and place herein prescribed.

         As provided in the Indenture and subject to certain limitations therein
set forth, the transfer of this Security is registrable in the Security
Register, upon surrender of this Security for registration of transfer at the
office or agency of the Company in any Place of Payment with respect to this
Security, duly endorsed by, or accompanied by a written instrument of transfer
in form satisfactory to the Company and the Security Registrar duly executed by,
the Holder hereof or his attorney duly authorized in writing, and thereupon one
or more new Securities of this series and of like tenor, of authorized
denominations and for the same number of Warrants, will be issued to the
designated transferee or transferees.

         The Securities of this series are issuable only in registered form in
denominations of . Warrants and any multiple thereof. As provided in the
Indenture and subject to certain limitations therein set forth, Securities of
this series are exchangeable for a like number of Warrants of this series and of
like tenor of a different authorized denomination, as requested by the Holder
surrendering the same.

         No service charge shall be made for any such registration of transfer
or exchange, but the Company may require payment of a sum sufficient to cover
any tax or other governmental charge payable in connection therewith.

         Prior to due presentment of this Security for registration of transfer,
the Company, the Trustee and any agent of the Company or the Trustee may treat
the Person in whose name this Security is registered as the owner hereof for all
purposes, whether or not any payment or delivery of money with respect to this
Security be overdue, and neither the Company, the Trustee nor any such agent
shall be affected by notice to the contrary.

         This Security is a Global Security and is subject to the provisions of
the Indenture relating to Global Securities, including the limitations in
Section 305 thereof on transfers and exchanges of Global Securities.

         This Security and the Indenture shall be governed by and construed in
accordance with the laws of the State of New York.

         All terms used in this Security which are defined in the Indenture
shall have the meanings assigned to them in the Indenture.


                                      -24-
<PAGE>   32
                       [Designation of Universal Warrants]

                                 Exercise Notice

[Trustee]
[Address]
Attn:    [name]                    [number]
         [name]                    [number]
         Fax:                      [number]
with a copy to:

[Insert name and address of Calculation Agent.]
Attn:                              Tel.:
                                   Tel.:
                                   Fax:

Re: Put Warrants on............expiring............, 20.., issued by UBS AG and
described in the prospectus supplement dated to the prospectus
dated............, 20..

Ladies and Gentlemen:

         The undersigned is, or is acting on behalf of, the beneficial owner of
such number of the Warrants referenced above as is specified at the end of this
Exercise Notice. The undersigned hereby irrevocably elects to exercise such
number of the Warrants. The exercise is to be effective on the Business Day on
which the Trustee has received this Exercise Notice, together with all other
items required to be delivered on exercise, and the Calculation Agent has
received a copy of this Exercise Notice, unless all required items have not been
received by 11:00 A.M., New York City time, on that Business Day, in which case
the exercise will be effective as of the next Business Day. We understand,
however, that no exercise shall be effective unless it is effective, as provided
above, no later than the Business Day before the Expiration Date. The effective
date will be the exercise notice date.

         If the Warrants to be exercised are in global form, the undersigned is
delivering this Exercise Notice to the Trustee and to the Calculation Agent, in
each case by facsimile transmission to the relevant number stated above, or such
other number as the Trustee or Calculation Agent may have designated for this
purpose to the Holder. In addition, the beneficial interest in the number of
Warrants indicated below is being transferred on the books of the Depositary to
an account of the Trustee at the Depositary.

         If the Warrants to be exercised are not in global form, the undersigned
or the beneficial owner is the Holder of the Warrants and is delivering this
Exercise Notice to the Trustee and to the Calculation Agent by facsimile
transmission as described above. In addition, the certificate representing the
Warrants is being delivered to the Trustee.

         If the undersigned is not the beneficial owner of the Warrant to be
exercised, the undersigned hereby represents that it has been duly authorized by
the beneficial owner to act on behalf of the beneficial owner.


                                      -25-
<PAGE>   33
         Terms used and not defined in this notice have the meanings given to
them in the Warrant or the Indenture specified in the Warrant. The exercise of
the Warrant will be governed by the terms of the Warrant and the Indenture.

         The calculation agent should note receipt of the copy of this exercise
notice, in the place provided below, on the business day of receipt, noting the
date and time of receipt. The consideration to be delivered or paid in the
requested exercise should be made on the .. business day after the exercise
notice date in accordance with the terms of the warrant.

Number of Warrants to be exercised:

--------------------------------------
(must be a number greater than or equal to )

Means of Payment of [Cash Settlement Value][Put Price]:

                                   Very truly yours,

                                   -----------------------------------
                                   (Name of beneficial owner or Person
                                   authorized to act on its behalf)

                                   -----------------------------------
                                   (Title)

                                   -----------------------------------
                                   (Telephone No.)

                                   -----------------------------------
                                   (Fax No.)

Receipt of the above exercise notice
is hereby noted:

     , as Calculation Agent

By:
   -----------------------------
(Title)

Date and time of receipt:

-------------------------------
(Date)

-------------------------------
(Time)




                                      -26-
<PAGE>   34
[If Security is a Global Security, insert this Schedule A.]

                       [DESIGNATION OF UNIVERSAL WARRANTS]

                                                                      SCHEDULE A



                                     GLOBAL
                                UNIVERSAL WARRANT
                       SCHEDULE OF EXCHANGES OR EXERCISES

         The initial number of Universal Warrants represented by this Global
Security is In accordance with the Indenture, dated as of ....................,
20.., between the Company and [Trustee], as Trustee, [If applicable, insert--
and the Unit Agreement, dated as of............, 20.., between the Company and
[Trustee], as Unit Agent, the following (A) exchanges of [the number of
Universal Warrants previously represented hereby and indicated below for a like
number of Universal Warrants represented by a Global Security that has been
separated from a Unit (a "Separated Universal Warrant")](1) [the number of
Universal Warrants previously represented by a Global Security that is part of a
Unit (an "Attached Unit Universal Warrant") and indicated below for a like
number of Universal Warrants represented by this Global Security](2) or (B)
reductions in the number of Universal Warrants represented hereby as a result of
the exercise of the number of such Warrants indicated below have been made:

<TABLE>
<CAPTION>
   Date of         [Number          [Reduced           [Number of          [Increased      Number of       Reduced        Notation
  Exchange        Exchanged          Number             Attached             Number        Universal       Number        Made by or
 or Exercise         for           Outstanding            Unit             Outstanding     Warrants      Outstanding      on Behalf
                  Separated         Following           Universal           Following      Exercised      Following      of Trustee
                  Universal           Such              Warrants              Such                          Such
                Warrants](1)      Exchange](1)          Exchanged         Exchange](2)                    Exercise
                                                      for Universal
                                                        Warrants
                                                       represented
                                                         by this
                                                        Separated
                                                        Universal
                                                       Warrant](2)
<S>             <C>              <C>                  <C>                 <C>             <C>            <C>

</TABLE>


(1)   Applies only if this Global Security is part of a Unit.

(2) Applies only if this Global Security has been separated from a Unit.

SECTION 206.   Form of Legend for Global Securities.

      Unless otherwise specified as contemplated by Section 301 for the
Securities evidenced thereby, every Global Security authenticated and delivered
hereunder shall bear a legend in substantially the following form:

THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A


                                      -27-
<PAGE>   35
NOMINEE THEREOF. THIS SECURITY MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR A
SECURITY REGISTERED, AND NO TRANSFER OF THIS SECURITY IN WHOLE OR IN PART MAY BE
REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH DEPOSITARY OR A NOMINEE
THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE.

Section 207.   Form of Trustee's Certificate of Authentication.

      The Trustee's certificates of authentication shall be in substantially the
following form:

      This is one of the Securities of the series designated therein and
referred to in the within-mentioned Indenture.

Dated:_________________

                              [Trustee], As Trustee

                              By____________________________________
                                Authorized Signatory


                                      -28-
<PAGE>   36
                                  ARTICLE THREE

                                 THE SECURITIES

SECTION 301.   Amount Unlimited; Issuable in Series.

      The aggregate number of Warrants which may be authenticated and delivered
under this Indenture is unlimited.

      The Securities may be issued in one or more series. There shall be
established in or pursuant to corporate authorization and, subject to Section
303, set forth, or determined in the manner provided, in an Officers'
Certificate, or established in one or more indentures supplemental hereto, prior
to the issuance of Securities of any series,

            (1) the title of the Securities of the series (which shall
      distinguish the Securities of the series from the Securities of any other
      series);

            (2) any limit upon the aggregate number of the Warrants of the
      series that may be authenticated and delivered under this Indenture
      (except for Securities authenticated and delivered upon registration of
      transfer of, or in exchange for, or in lieu of, other Securities of the
      series pursuant to Section 304, 305, 306, 906 or 1107 and except for any
      Securities which, pursuant to Section 303, are deemed never to have been
      authenticated and delivered hereunder);

            (3) the money payable or receivable or specific Warrant Property
      purchasable or deliverable by or on behalf of the Holder upon exercise of
      the Securities of the series, and the amount thereof (or the method for
      determining the same);

            (4) the price at which the Securities of the series will be issued
      and, if other than the currency of the United States of America, the
      currency, currencies, composite currency, composite currencies or currency
      units in which such issue price will be payable and the manner of
      determining the equivalent thereof in the currency of the United States of
      America for any purpose, including for purposes of the definition of
      "Outstanding" in Section 101;

            (5) whether the Securities of the series are warrants to purchase
      the Warrant Property (including warrants that may be settled by means of
      net cash settlement or cashless exercise) ("Call Warrants"), warrants to
      sell the Warrant Property (including warrants that may be settled by means
      of net cash settlement or cashless exercise) ("Put Warrants") or any other
      type of warrants;

            (6) the price at which and, if other than the currency of the United
      States of America, the currency, currencies, composite currency, composite
      currencies or currency units with which, the Warrant Property may be
      purchased or sold by or on behalf of the Holder upon exercise of the
      Securities of the series (or the method for determining the same);

            (7) the period or periods within which, the price or prices at which
      and the terms and conditions upon which any Securities of the series may
      be redeemed, in whole or in part, at the option of the Company and, if
      other than by a Board Resolution, the manner in which any election by the
      Company to redeem the Securities shall be evidenced;


                                      -29-
<PAGE>   37
            (8) whether the exercise price for the Securities of the series may
      be paid in cash or by the exchange of any such Securities or other
      securities of the Company, or both, or otherwise, whether such exercise
      price may be netted against any money or Warrant Property payable or
      deliverable by the Company with respect to such Securities and the method
      of exercise of such Securities;

            (9) if the Securities of the series are call warrants, whether the
      exercise of such Securities is to be settled by payment in cash or
      delivery of the Warrant Property by the Company or both or otherwise, and
      whether the election of such form of settlement is to be at the option of
      the Holder or of the Company ;

            (10) if the Securities of the series are put warrants, whether the
      exercise of such Securities is to be settled by payment in cash or
      delivery of the Warrant Property by the Holder or both, or otherwise, and
      whether the election of such form of settlement is to be at the option of
      the Holder or of the Company;

            (11) the date on which the right to exercise the Securities of the
      series shall commence and the Expiration Date of the series or, if the
      Securities of the series are not continuously exercisable throughout such
      period, the specific date or dates on which they will be exercisable;

            (12) if applicable, that any Securities of the series shall be
      issuable in whole or in part in the form of one or more Global Securities
      and, in such case, the respective Depositaries for such Global Securities,
      the form of any legend or legends which shall be borne by any such Global
      Security in addition to or in lieu of that set forth in Section 206, and
      any circumstances in addition to or in lieu of those set forth in Clause
      (2) of the last paragraph of Section 305 in which any such Global Security
      may be exchanged in whole or in part for Securities registered, and any
      transfer of such Global Security in whole or in part may be registered, in
      the name or names of Persons other than the Depositary for such Global
      Security or a nominee thereof and any other provisions governing exchanges
      or transfers of any such Global Security;

            (13) any warrant agents, Depositaries, Paying Agents, transfer
      agents or registrars or any determination agents, Calculation Agents or
      other agents with respect to Securities of the series;

            (14) whether the Securities of the series will be issued separately
      or together as a unit (a "Unit") with one or more other securities of the
      Company or any other person and, if the Securities of the series are to be
      issued as components of Units, whether and on what terms the Securities of
      the series may be separated from the other components of such Units prior
      to the Expiration Date of such Securities;

            (15) if other than denominations of 100 Warrants and any multiple
      thereof, the denominations in which any Securities of the series shall be
      issuable;

            (16) the Place of Payment with respect to Securities of the series,
      if other than the Corporate Trust Office;

            (17) any addition to or change in the covenants set forth in Article
      Ten which applies to Securities of the series;


                                      -30-
<PAGE>   38
            (18) any provisions necessary to permit or facilitate the issuance,
      payment or exercise of any Securities of the series that may be exercised
      for securities or other property other than Securities of the same series
      and of like tenor, whether in addition to, or in lieu of, any payment of
      money or delivery of other property and whether at the option of the
      Company or otherwise;

            (19) any addition to, elimination of or other change in the Events
      of Default which applies to Securities of the series, including making
      Events of Default inapplicable or changing the remedies available to
      Holders of the Securities of the series upon an Event of Default; and

            (20) if applicable, that Additional Amounts, pursuant to Section
      1007, will not be payable by the Company in respect of the Securities of
      the series; and

            (21) any other terms of the series (which terms shall not be
      inconsistent with the provisions of this Indenture, except as permitted by
      Section 901(5)).

      All Securities of any one series shall be substantially identical except
as to denomination and except as may otherwise be provided in or pursuant to the
Board Resolution referred to above and (subject to Section 303) set forth, or
determined in the manner provided, in the Officers' Certificate referred to
above or in any such indenture supplemental hereto.

      If any of the terms of the series are established by action taken pursuant
to a Board Resolution, a copy of an appropriate record of such action shall be
certified by the Secretary or an Assistant Secretary of the Company and
delivered to the Trustee at or prior to the delivery of the Officers'
Certificate setting forth the terms of the series.

      The Securities are unsecured contractual obligations of the Company and
rank pari passu with the Company's other unsecured contractual obligations and
with the Company's unsecured and unsubordinated debt.

      No Security shall entitle the Holder or any beneficial owner thereof to
any of the rights of a holder or beneficial owner of Warrant Property, including
the right to receive the payment of any dividends on, principal of, or premium
or interest on Warrant Property or to vote or to enforce any rights under any
documents governing Warrant Property.

SECTION 302.   Denominations.

      The Securities of each series shall be issuable only in registered form
without coupons and only in such denominations as shall be specified as
contemplated by Section 301. In the absence of any such specified denomination
with respect to the Securities of any series, the Securities of such series
shall be issuable in denominations of 100 Warrants and any multiple thereof.

SECTION 303.   Execution, Authentication, Delivery and Dating.

      The Securities shall be executed on behalf of the Company by any two
Authorized Officers. The signature of any of these officers on the Securities
may be manual or facsimile.


                                      -31-
<PAGE>   39
      Securities bearing the manual or facsimile signatures of individuals who
were at any time the proper officers of the Company shall bind the Company,
notwithstanding that such individuals or any of them have ceased to hold such
offices prior to the authentication and delivery of such Securities or did not
hold such offices at the date of such Securities.

      At any time and from time to time after the execution and delivery of this
Indenture, the Company may deliver Securities of any series executed by the
Company to the Trustee for authentication, together with a Company Order for the
authentication and delivery of such Securities, and the Trustee in accordance
with the Company Order shall authenticate and deliver such Securities. If the
form or terms of the Securities of the series have been established by or
pursuant to one or more Board Resolutions as permitted by Sections 201 and 301,
in authenticating such Securities, and accepting the additional responsibilities
under this Indenture in relation to such Securities, the Trustee shall be
entitled to receive, and (subject to Section 601) shall be fully protected in
relying upon, an Opinion of Counsel stating,

            (1) if the form of such Securities has been established by or
      pursuant to Board Resolution as permitted by Section 201, that such form
      has been established in conformity with the provisions of this Indenture;

            (2) if the terms of such Securities have been established by or
      pursuant to Board Resolution as permitted by Section 301, that such terms
      have been established in conformity with the provisions of this Indenture;
      and

            (3) that such Securities, when authenticated and delivered by the
      Trustee and issued by the Company in the manner and subject to any
      conditions specified in such Opinion of Counsel, will constitute valid and
      legally binding obligations of the Company enforceable in accordance with
      their terms, subject to bankruptcy, insolvency, fraudulent transfer,
      reorganization, moratorium and similar laws of general applicability
      relating to or affecting creditors' rights and to general equity
      principles.

      If such form or terms have been so established, the Trustee shall not be
required to authenticate such Securities if the issue of such Securities
pursuant to this Indenture will affect the Trustee's own rights, duties or
immunities under the Securities and this Indenture or otherwise in a manner
which is not reasonably acceptable to the Trustee.

      Notwithstanding the provisions of Section 301 and of the preceding
paragraph, if all Securities of a series are not to be originally issued at one
time, it shall not be necessary to deliver the Officers' Certificate otherwise
required pursuant to Section 301 or the Company Order and Opinion of Counsel
otherwise required pursuant to such preceding paragraph at or prior to the
authentication of each Security of such series if such documents are delivered
at or prior to the authentication upon original issuance of the first Security
of such series to be issued.

      Each Security shall be dated the date of its authentication.

      No Security shall be entitled to any benefit under this Indenture or be
valid or obligatory for any purpose unless there appears on such Security a
certificate of authentication substantially in the form provided for herein
executed by the Trustee by manual signature, and such certificate upon any
Security shall be conclusive evidence, and the only evidence, that such Security
has been duly authenticated and


                                      -32-
<PAGE>   40
delivered hereunder. Notwithstanding the foregoing, if any Security shall have
been authenticated and delivered hereunder but never issued and sold by the
Company, and the Company shall deliver such Security to the Trustee for
cancellation as provided in Section 309, for all purposes of this Indenture such
Security shall be deemed never to have been authenticated and delivered
hereunder and shall never be entitled to the benefits of this Indenture.

SECTION 304.   Temporary Securities.

      Pending the preparation of definitive Securities of any series, the
Company may execute, and upon Company Order the Trustee shall authenticate and
deliver, temporary Securities which are printed, lithographed, typewritten,
mimeographed or otherwise produced, in any authorized denomination,
substantially of the tenor of the definitive Securities in lieu of which they
are issued and with such appropriate insertions, omissions, substitutions and
other variations as the officers executing such Securities may determine, as
evidenced by their execution of such Securities.

      If temporary Securities of any series are issued, the Company will cause
definitive Securities of that series to be prepared without unreasonable delay.
After the preparation of definitive Securities of such series, the temporary
Securities of such series shall be exchangeable for definitive Securities of
such series upon surrender of the temporary Securities of such series at the
office or agency of the Company in a Place of Payment for that series, without
charge to the Holder. Upon surrender for cancellation of any one or more
temporary Securities of any series, the Company shall execute and the Trustee
shall authenticate and deliver in exchange therefor one or more definitive
Securities of the same series, of any authorized denominations and of like tenor
and aggregate number of Warrants. Until so exchanged, the temporary Securities
of any series shall in all respects be entitled to the same benefits under this
Indenture as definitive Securities of such series and tenor.

SECTION 305.   Registration, Registration of Transfer and Exchange.

      The Company shall cause to be kept at the Corporate Trust Office of the
Trustee a register (the register maintained in such office and in any other
office or agency of the Company in a Place of Payment being herein sometimes
collectively referred to as the "Security Register") in which, subject to such
reasonable regulations as it may prescribe, the Company shall provide for the
registration of Securities and of transfers of Securities. The Trustee is hereby
appointed "Security Registrar" for the purpose of registering Securities and
transfers of Securities as herein provided.

      Upon surrender for registration of transfer of any Security of a series at
the office or agency of the Company in a Place of Payment for that series, the
Company shall execute, and the Trustee shall authenticate and deliver, in the
name of the designated transferee or transferees, one or more new Securities of
the same series, of any authorized denominations and of like tenor and aggregate
number of Warrants.

      At the option of the Holder, Securities of any series may be exchanged for
other Securities of the same series, of any authorized denominations and of like
tenor and aggregate number of Warrants, upon surrender of the Securities to be
exchanged at such office or agency. Whenever any Securities are so surrendered
for exchange, the Company shall execute, and the Trustee shall authenticate and
deliver, the Securities which the Holder making the exchange is entitled to
receive.


                                      -33-
<PAGE>   41
      All Securities issued upon any registration of transfer or exchange of
Securities shall be the valid obligations of the Company, evidencing the same
contractual obligation, and entitled to the same benefits under this Indenture,
as the Securities surrendered upon such registration of transfer or exchange.

      Every Security presented or surrendered for registration of transfer or
for exchange shall (if so required by the Company or the Trustee) be duly
endorsed, or be accompanied by a written instrument of transfer in form
satisfactory to the Company and the Security Registrar duly executed, by the
Holder thereof or his attorney duly authorized in writing.

      No service charge shall be made for any registration of transfer or
exchange of Securities, but the Company may require payment of a sum sufficient
to cover any tax or other governmental charge that may be imposed in connection
with any registration of transfer or exchange of Securities, other than
exchanges pursuant to Section 304, 906 or 1107 not involving any transfer.

      If the Securities of any series are to be redeemed in part, the Company
shall not be required (A) to issue, register the transfer of or exchange any
Securities of that series during a period beginning at the opening of business
15 days before the day of the mailing of a notice of redemption of any such
Securities selected for redemption under Section 1103 and ending at the close of
business on the day of such mailing (or during such period as otherwise
specified as contemplated by Section 301 for such Securities), or (B) to
register the transfer of or exchange any Security so selected for redemption in
whole or in part, except the unredeemed portion of any Security being redeemed
in part.

      The provisions of Clauses (1), (2), (3), (4) and (5) below shall apply
only to Global Securities:

            (1) Each Global Security authenticated under this Indenture shall be
      registered in the name of the Depositary designated for such Global
      Security or a nominee thereof and delivered to such Depositary or a
      nominee thereof or custodian therefor, and each such Global Security shall
      constitute a single Security for all purposes of this Indenture.

            (2) Notwithstanding any other provision in this Indenture, and
      subject to such applicable provisions, if any, as may be specified as
      contemplated by Section 301, no Global Security may be exchanged in whole
      or in part for Securities registered, and no transfer of a Global Security
      in whole or in part may be registered, in the name of any Person other
      than the Depositary for such Global Security or a nominee thereof unless
      (A) such Depositary (i) has notified the Company that it is unwilling or
      unable to continue as Depositary for such Global Security or (ii) has
      ceased to be a clearing agency registered under the Exchange Act, (B)
      there shall have occurred and be continuing an Event of Default with
      respect to such Global Security or (C) there shall exist such
      circumstances, if any, in addition to or in lieu of the foregoing as have
      been specified for this purpose as contemplated by Section 301.


                                      -34-
<PAGE>   42

            (3) Subject to Clause (2) above and to such applicable provisions,
      if any, as may be specified as contemplated by Section 301, any exchange
      of a Global Security for other Securities may be made in whole or in part,
      and all Securities issued in exchange for a Global Security or any portion
      thereof shall be registered in such names as the Depositary for such
      Global Security shall direct.

            (4) Every Security authenticated and delivered upon registration of
      transfer of, or in exchange for or in lieu of, a Global Security or any
      portion thereof, whether pursuant to this Section, Section 304, 306, 906
      or 1107 or otherwise, shall be authenticated and delivered in the form of,
      and shall be, a Global Security, unless such Security is registered in the
      name of a Person other than the Depositary for such Global Security or a
      nominee thereof.

            (5) Except for the exchange rights provided in Clause (2) above,
      owners of beneficial interest in a Global Security held on their behalf by
      a Depositary shall not be entitled to receive physical delivery of
      Securities in definitive form, shall not be considered the Holders thereof
      for any purpose under this Indenture and shall have no rights under this
      Indenture with respect to such Global Security, and such Depositary may be
      treated by the Company, the Trustee and any agent of any of them as the
      Holder and owner of such Global Security for all purposes whatsoever.
      Notwithstanding the foregoing, the Depositary for any Global Security may
      grant proxies and otherwise authorize any person, including the beneficial
      owners of interest in such Global Security, to take any action which a
      Holder is entitled to take under this Indenture with respect to such
      Global Security.

      In the event that upon any exercise of Warrants evidenced by a certificate
the number of Warrants exercised shall be less than the total number of Warrants
evidenced by such certificate, there shall be issued to the Holder thereof or
his assignee a new certificate evidencing the number of Warrants of the same
series and of like tenor not exercised, provided that in the case of Warrants
evidenced by one or more Global Securities, in lieu of issuing such new
certificate the Trustee shall note the cancellation of such exercised Warrants
and the number of such Warrants not exercised and remaining Outstanding by
notation on such Global Security(ies).

SECTION 306.   Mutilated, Destroyed, Lost and Stolen Securities.

      If any mutilated Security is surrendered to the Trustee, the Company shall
execute and the Trustee shall authenticate and deliver in exchange therefor a
new Security of the same series and of like tenor and number of Warrants and
bearing a number not contemporaneously outstanding.

      If there shall be delivered to the Company and the Trustee (i) evidence to
their satisfaction of the destruction, loss or theft of any Security and (ii)
such security or indemnity as may be required by them to save each of them and
any agent of either of them harmless, then, in the absence of notice to the
Company or the Trustee that such Security has been acquired by a bona fide
purchaser, the Company shall execute and the Trustee shall authenticate and
deliver, in lieu of any such destroyed, lost or stolen


                                      -35-
<PAGE>   43
Security, a new Security of the same series and of like tenor and number of
Warrants and bearing a number not contemporaneously outstanding.

      In case any such mutilated, destroyed, lost or stolen Security has been or
is about to be exercised, or deemed to be exercised, the Company in its
discretion may, instead of issuing a new Security, direct the Trustee to treat
the same as if it had received the Security together with an irrevocable
exercise notice in proper form in respect thereof, as established with respect
to the Securities of such series.

      Upon the issuance of any new Security under this Section, the Company may
require the payment of a sum sufficient to cover any tax or other governmental
charge that may be imposed in relation thereto and any other expenses (including
the fees and expenses of the Trustee) connected therewith.

      Every new Security of any series issued pursuant to this Section in lieu
of any destroyed, lost or stolen Security shall constitute an original
additional contractual obligation of the Company, whether or not the destroyed,
lost or stolen Security shall be at any time enforceable by anyone, and shall be
entitled to all the benefits of this Indenture equally and proportionately with
any and all other Securities of that series duly issued hereunder.

      The provisions of this Section are exclusive and shall preclude (to the
extent lawful) all other rights and remedies with respect to the replacement,
payment or settlement of mutilated, destroyed, lost or stolen Securities.

SECTION 307.   Persons Deemed Owners.

      Prior to due presentment of a Security for registration of transfer, the
Company, the Trustee and any agent of the Company or the Trustee may treat the
Person in whose name such Security is registered as the owner of such Security
for the purpose of receiving payment or delivery of any money or Warrant
Property payable or deliverable with respect to such Security and for all other
purposes whatsoever, whether or not such payment or delivery with respect to
such Security be overdue, and neither the Company, the Trustee nor any agent of
the Company or the Trustee shall be affected by notice to the contrary.

SECTION 308.   Cancellation.

      All Securities surrendered for exercise, redemption or registration of
transfer or exchange shall, if surrendered to any Person other than the Trustee,
be delivered to the Trustee and shall be promptly canceled by it. The Company
may at any time deliver to the Trustee for cancellation any Securities
previously authenticated and delivered hereunder which the Company may have
acquired in any manner whatsoever, and may deliver to the Trustee (or to any
other Person for delivery to the Trustee) for cancellation any Securities
previously authenticated hereunder which the Company has not issued and sold,
and all Securities so delivered shall be promptly cancelled by the Trustee. No
Securities shall be authenticated in lieu of or in exchange for any Securities
cancelled as provided in this Section, except as expressly permitted by this
Indenture. All canceled Securities held by the Trustee shall be disposed of as
directed by a Company Order.


                                      -36-
<PAGE>   44
SECTION 309.   CUSIP Numbers.

      The Company in issuing the Securities may use CUSIP numbers (if then
generally in use) and, if so, the Trustee shall use CUSIP numbers in notices of
redemption as a convenience to Holders, provided that any such notice may state
that no representation is made as to the correctness of such numbers either as
printed on the Securities or as contained in any notice of redemption and that
reliance may be placed only on the other identification numbers printed on the
Securities. Any such redemption shall not be affected by any defect in or
omission of such numbers.

SECTION 310.   Calculation Agent.

      Pursuant to Section 301, the Company may, in connection with any series of
Securities, appoint UBS Warburg LLC or any other person or entity as Calculation
Agent to make any calculations as may be required pursuant to the terms of such
series of Securities. Any such Calculation Agent shall act as an independent
expert, and the Company may provide that the Calculation Agent's calculations
and determinations under this Indenture shall, absent manifest error, be final
and binding on the Company, the Trustee and the Holders of the Securities of
such series.


                                      -37-
<PAGE>   45
                                  ARTICLE FOUR

                           SATISFACTION AND DISCHARGE

SECTION 401.   Satisfaction and Discharge of Indenture.

      This Indenture shall upon Company Request cease to be of further effect
(except as to any surviving rights of exercise, registration of transfer or
exchange of Securities herein expressly provided for, and the Trustee, at the
expense of the Company, shall execute without recourse, representation or
warranty of any kind, proper instruments acknowledging satisfaction and
discharge of this Indenture, when

            (1) either

                  (A) all Securities theretofore authenticated and delivered
            (other than (i) Securities which have been destroyed, lost or stolen
            and which have been replaced, paid or settled as provided in Section
            306 and (ii) Securities for whose payment or settlement money or
            Warrant Property has theretofore been deposited in trust or
            segregated and held in trust by the Company and thereafter repaid or
            redelivered to the Company or discharged from such trust, as
            provided in Section 1003) have been delivered to the Trustee for
            cancellation; or

                  (B) all such Securities not theretofore delivered to the
            Trustee for cancellation

                        (i)  have been exercised,

                        (ii) will be automatically exercised at their Expiration
                  Date within one year, or

                        (iii) are to be called for redemption within one year
                  under arrangements satisfactory to the Trustee for the giving
                  of notice of redemption by the Trustee in the name, and at the
                  expense, of the Company, and the Company, in the case of (i),
                  (ii) or (iii) above, has deposited or caused to be deposited
                  with the Trustee as trust funds or trust property in trust for
                  the purpose money or Warrant Property in an amount sufficient
                  to pay and discharge the entire contractual obligation on such
                  Securities not theretofore delivered to the Trustee for
                  cancellation, for all amounts of money or Warrant Property due
                  with respect to such Securities to the date of such deposit or
                  to the Payment or Settlement Date or Redemption Date of such
                  Securities, as the case may be;

            (2) the Company has paid or caused to be paid all other sums payable
      hereunder by the Company; and

            (3) the Company has delivered to the Trustee an Officers'
      Certificate and an Opinion of Counsel, each stating that all conditions
      precedent herein provided for relating to the satisfaction and discharge
      of this Indenture have been complied with.


                                      -38-
<PAGE>   46
      Notwithstanding the satisfaction and discharge of this Indenture, the
obligations of the Company to the Trustee under Section 607, the obligations of
the Trustee to any Authenticating Agent under Section 614 and, if money or
Warrant Property shall have been deposited with the Trustee pursuant to
subclause (B) of Clause (1) of this Section, the obligations of the Trustee
under Section 402 and the last paragraph of Section 1003 shall survive.

SECTION 402.   Application of Trust Money and Warrant Property.

      Subject to the provisions of the last paragraph of Section 1003, all money
and Warrant Property deposited with the Trustee pursuant to Section 401 shall be
held in trust and applied by it, in accordance with the provisions of the
Securities and this Indenture, to the payment or delivery, either directly or
through any Paying Agent (including the Company acting as its own Paying Agent)
as the Trustee may determine, to the Persons entitled thereto, of all amounts of
money or Warrant Property due with respect to such Securities for whose payment
or settlement such money or Warrant Property has been deposited with the
Trustee.


                                      -39-
<PAGE>   47
                                  ARTICLE FIVE

                                    REMEDIES

SECTION 501.   Events of Default.

      "Event of Default", wherever used herein with respect to Securities of any
series, means any one of the following events (whatever the reason for such
Event of Default and whether it shall be voluntary or involuntary or be effected
by operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body):

            (1) default in the payment or delivery of any money or Warrant
      Property in respect of such Security (but not such a default in respect of
      any other Security of that or any other series) in accordance with its
      terms; or

            (2) default in the performance, or breach, of any covenant or
      warranty of the Company in this Indenture (other than a covenant or
      warranty a default in whose performance or whose breach is elsewhere in
      this Section specifically dealt with or which has expressly been included
      in this Indenture solely for the benefit of series of Securities other
      than that series), and continuance of such default or breach for a
      period of 60 days after there has been given, by registered or certified
      mail, to the Company by the Trustee or to the Company and the Trustee by
      the Holders of at least 10% in number of the Outstanding Warrants of that
      series a written notice specifying such default or breach and requiring it
      to be remedied and stating that such notice is a "Notice of Default"
      hereunder; or

            (3) the entry by a court having jurisdiction in the premises of (A)
      a decree or order for relief in respect of the Company in an involuntary
      case or proceeding under any applicable Swiss bankruptcy, insolvency,
      reorganization or other similar law or (B) a decree or order appointing a
      custodian, receiver, liquidator, assignee, trustee, sequestrator or other
      similar official of the Company or of any substantial part of its
      property, or ordering the winding up or liquidation of its affairs, and
      the continuance of any such decree or order for relief or any such other
      decree or order unstayed and in effect for a period of 60 consecutive
      days; or

            (4) the commencement by the Company of a voluntary case or
      proceeding under any applicable Swiss bankruptcy, insolvency,
      reorganization or other similar law or of any other case or proceeding to
      be adjudicated a bankrupt or insolvent, or the consent by it to the entry
      of a decree or order for relief in respect of the Company in an
      involuntary case or proceeding under


                                      -40-
<PAGE>   48
      any applicable Swiss bankruptcy, insolvency, reorganization or other
      similar law or to the commencement of any bankruptcy or insolvency case or
      proceeding against it, or the filing by it of a petition or answer or
      consent seeking reorganization or relief under any applicable Swiss law,
      or the consent by it to the filing of such petition or to the appointment
      of or taking possession by a custodian, receiver, liquidator, assignee,
      trustee, sequestrator or other similar official of the Company or of any
      substantial part of its property, or the making by it of an assignment for
      the benefit of creditors, or the taking of corporate action by the Company
      in furtherance of any such action; or

            (5) any other Event of Default provided with respect to such
      Security or to Securities of that series.

      Notwithstanding any other provision of this Indenture or of any Security,
a failure by the Company to perform any obligation or otherwise observe any
covenant in any Security or in this Indenture insofar as it applies to any
Security shall not constitute a default unless all conditions precedent to the
Company's obligation to be satisfied by the Holder of such Security shall have
been satisfied.

SECTION 502.   Collection of Amounts Due and Suits for Enforcement by Trustee.

      The Company covenants that if default is made in the payment or delivery
of any money or Warrant Property in respect of any Security in accordance with
its terms upon satisfaction by the Holder thereof of all conditions precedent to
the Company's obligation to make such payment or delivery to be satisfied by
such Holder, the Company will, upon demand of the Trustee, pay to it, for the
benefit of the Holder of such Security, the whole amount of Warrant Property or
money then due and payable on such Security and, in addition thereto, such
further amount as shall be sufficient to cover the costs and expenses of
collection, including the reasonable compensation, expenses, disbursements and
advances of the Trustee, its agents and counsel.

      If an Event of Default with respect to any Security occurs and is
continuing, the Trustee may in its discretion proceed to protect and enforce its
rights and the rights of the Holder of such Security by such appropriate
judicial proceedings as the Trustee shall deem most effectual to protect and
enforce any such rights, whether for the specific enforcement of any covenant or
agreement in this Indenture or in aid of the exercise of any power granted
herein, or to enforce any other proper remedy.

Section 503.   Trustee May File Proofs of Claim.

      In case of any judicial proceeding relative to the Company (or any other
obligor upon the Securities), its property or its creditors, the Trustee shall
be entitled and empowered, by intervention in such proceeding or otherwise, to
take any and all actions authorized under the Trust Indenture Act in order to
have claims of the Holders and the Trustee allowed in any such proceeding. In
particular, the


                                      -41-
<PAGE>   49
Trustee shall be authorized to participate as a member, voting or otherwise, of
any official committee appointed on such matter, to collect and receive any
moneys, Warrant Property or other property payable or deliverable on any such
claims and to distribute the same; and any custodian, receiver, assignee,
trustee, liquidator, sequestrator or other similar official in any such judicial
proceeding is hereby authorized by each Holder to make such payments to the
Trustee and, in the event that the Trustee shall consent to the making of such
payments directly to the Holders, to pay to the Trustee any amount due it for
the reasonable compensation, expenses, disbursements and advances of the
Trustee, its agents and counsel, and any other amounts due the Trustee under
Section 607.

      No provision of this Indenture shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder any plan of
reorganization, arrangement, adjustment or composition affecting the Securities
or the rights of any Holder thereof or to authorize the Trustee to vote in
respect of the claim of any Holder in any such proceeding; provided, however,
that the Trustee may, on behalf of the Holders, vote for the election of a
trustee in bankruptcy or similar official and be a member of a creditors' or
other similar committee.

SECTION 504.   Trustee May Enforce Claims Without Possession of Securities.

      All rights of action and claims under this Indenture or the Securities may
be prosecuted and enforced by the Trustee without the possession of any of the
Securities or the production thereof in any proceeding relating thereto, and any
such proceeding instituted by the Trustee shall be brought in its own name as
trustee of an express trust, and any recovery of judgment shall, after provision
for the payment of the reasonable compensation, expenses, disbursements and
advances of the Trustee, its agents and counsel, be for the ratable benefit of
the Holders of the Securities in respect of which such judgment has been
recovered.

SECTION 505.   Application of Money Collected.

      Any money collected by the Trustee pursuant to this Article shall be
applied in the following order, at the date or dates fixed by the Trustee and,
in case of the distribution of such money on account of amounts due with respect
to the Securities, upon presentation of the Securities and the notation thereon
of the payment if only partially paid and upon surrender thereof if fully paid:

      FIRST: To the payment of all amounts due the Trustee under Section
607; and

      SECOND: To the payment of the amounts then due and unpaid on the
Securities in respect of which or for the benefit of which such money has been
collected, ratably, without preference or priority of any kind, according to the
amounts due and payable on such Securities.

SECTION 506.   Limitation on Suits.

      No Holder of any Security of any series shall have any right to institute
any proceeding, judicial or otherwise, with respect to this Indenture, or for
the appointment of a receiver or trustee, or for any other remedy hereunder,
unless

            (1) such Holder has previously given written notice to the Trustee
      of a continuing Event


                                      -42-
<PAGE>   50
      of Default with respect to the Securities of that series;

            (2) the Holders of not less than 25% in number of the Outstanding
      Securities of that series shall have made written request to the Trustee
      to institute proceedings in respect of such Event of Default in its own
      name as Trustee hereunder;

            (3) such Holder or Holders have offered to the Trustee reasonable
      indemnity against the costs, expenses and liabilities to be incurred in
      compliance with such request;

            (4) the Trustee for 60 days after its receipt of such notice,
      request and offer of indemnity has failed to institute any such
      proceeding; and

            (5) no direction inconsistent with such written request has been
      given to the Trustee during such 60-day period by the Holders of a
      majority in number of the Outstanding Securities of that series;

it being understood and intended that no one or more of such Holders shall have
any right in any manner whatever by virtue of, or by availing of, any provision
of this Indenture to affect, disturb or prejudice the rights of any other of
such Holders, or to obtain or to seek to obtain priority or preference over any
other of such Holders or to enforce any right under this Indenture, except in
the manner herein provided and for the equal and ratable benefit of all of such
Holders.

SECTION 507. Unconditional Right of Holders to Receive Money or Warrant Property
             Due With Respect to Securities and to Exercise.

      Notwithstanding any other provision in this Indenture, the Holder of any
Security shall have the right, which is absolute and unconditional, to receive
payment or delivery of the money or Warrant Property due with respect to such
Security on the Payment or Settlement Date (or, in the case of redemption, on
the Redemption Date) of such Security and to exercise such Security in
accordance with its terms, and to institute suit for the enforcement of any such
payment or delivery and such right to exercise, and such rights shall not be
impaired without the consent of such Holder.

SECTION 508.   Restoration of Rights and Remedies.

      If the Trustee or any Holder has instituted any proceeding to enforce any
right or remedy under this Indenture and such proceeding has been discontinued
or abandoned for any reason, or has been determined adversely to the Trustee or
to such Holder, then and in every such case, subject to any determination in
such proceeding, the Company, the Trustee and the Holders shall be restored
severally and respectively to their former positions hereunder and thereafter
all rights and remedies of the Trustee and the Holders shall continue as though
no such proceeding had been instituted.

SECTION 509.   Rights and Remedies Cumulative.

      Except as otherwise provided with respect to the replacement, payment or
settlement of mutilated, destroyed, lost or stolen Securities in the last
paragraph of Section 306, no right or remedy herein conferred upon or reserved
to the Trustee or to the Holders is intended to be exclusive of any other right
or remedy, and every right and remedy shall, to the extent permitted by law, be
cumulative


                                      -43-
<PAGE>   51
and in addition to every other right and remedy given hereunder or now or
hereafter existing at law or in equity or otherwise. The assertion or employment
of any right or remedy hereunder, or otherwise, shall not prevent the concurrent
assertion or employment of any other appropriate right or remedy.

SECTION 510.   Delay or Omission Not Waiver.

      No delay or omission of the Trustee or of any Holder of any Securities to
exercise any right or remedy accruing upon any Event of Default shall impair any
such right or remedy or constitute a waiver of any such Event of Default or an
acquiescence therein. Every right and remedy given by this Article or by law to
the Trustee or to the Holders may be exercised from time to time, and as often
as may be deemed expedient, by the Trustee or by the Holders, as the case may
be.

SECTION 511.   Control by Holders.

      The Holders of a majority in number of the Outstanding Warrants of any
series shall have the right to direct the time, method and place of conducting
any proceeding for any remedy available to the Trustee, or exercising any trust
or power conferred on the Trustee, with respect to the Securities of such
series, provided that

            (1) such direction shall not be in conflict with any rule of law or
      with this Indenture, and

            (2) the Trustee may take any other action deemed proper by the
      Trustee which is not inconsistent with such direction.

SECTION 512.   Waiver of Past Defaults.

      The Holders of not less than a majority in number of the Outstanding
Warrants of any series may on behalf of the Holders of all the Securities of
such series waive any past default hereunder with respect to such series and its
consequences, except a default

            (1) in the payment or delivery of the money or Warrant Property due
      on any Security of such series or in respect of any Holder's right to
      exercise any Security, or

            (2) in respect of a covenant or provision hereof which under Article
      Nine cannot be modified or amended without the consent of the Holder of
      each Outstanding Security of such series affected.

      Upon any such waiver, such default shall cease to exist, and any Event of
Default arising therefrom shall be deemed to have been cured, for every purpose
of this Indenture; but no such waiver shall extend to any subsequent or other
default or impair any right consequent thereon.

SECTION 513.   Undertaking for Costs.

      In any suit for the enforcement of any right or remedy under this
Indenture, or in any suit against the Trustee for any action taken, suffered or
omitted by it as Trustee, a court may require any party litigant in such suit to
file an undertaking to pay the costs of such suit, and may assess costs against
any such party litigant, in the manner and to the extent provided in the Trust
Indenture Act; provided that neither this Section nor the Trust Indenture Act


                                      -44-
<PAGE>   52
shall be deemed to authorize any court to require such an undertaking or to make
such an assessment in any suit instituted by the Company.

SECTION 514.   Waiver of Usury, Stay or Extension Laws.

      The Company covenants (to the extent that it may lawfully do so) that it
will not at any time insist upon, or plead, or in any manner whatsoever claim or
take the benefit or advantage of, any usury, stay or extension law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture; and the Company (to the extent that it may
lawfully do so) hereby expressly waives all benefit or advantage of any such law
and covenants that it will not hinder, delay or impede the execution of any
power herein granted to the Trustee, but will suffer and permit the execution of
every such power as though no such law had been enacted.


                                      -45-
<PAGE>   53
                                   ARTICLE SIX

                                   THE TRUSTEE

SECTION 601.   Certain Duties and Responsibilities.

      The duties and responsibilities of the Trustee shall be as provided by the
Trust Indenture Act. Notwithstanding the foregoing, no provision of this
Indenture shall require the Trustee to expend or risk its own funds or otherwise
incur any financial liability in the performance of any of its duties hereunder,
or in the exercise of any of its rights or powers, if it shall have reasonable
grounds for believing that repayment of such funds or adequate indemnity against
such risk or liability is not reasonably assured to it. Whether or not therein
expressly so provided, every provision of this Indenture relating to the conduct
or affecting the liability of or affording protection to the Trustee shall be
subject to the provisions of this Section.

SECTION 602.   Notice of Defaults.

      If a default occurs hereunder with respect to Securities of any series,
the Trustee shall give the Holders of Securities of such series notice of such
default as and to the extent provided by the Trust Indenture Act; provided,
however, that in the case of any default of the character specified in Section
501(2) with respect to Securities of such series, no such notice to Holders
shall be given until at least 30 days after the occurrence thereof. For the
purpose of this Section, the term "default" means any event which is, or after
notice or lapse of time or both would become, an Event of Default with respect
to Securities of such series.

SECTION 603.   Certain Rights of Trustee.

      Subject to the provisions of Section 601:

            (1) the Trustee may rely and shall be protected in acting or
      refraining from acting upon any resolution, certificate, statement,
      instrument, opinion, report, notice, request, direction, consent, order,
      warrant or other paper or document believed by it to be genuine and to
      have been signed or presented by the proper party or parties;

            (2) any request or direction of the Company mentioned herein shall
      be sufficiently evidenced by a Company Request or Company Order, and any
      resolution of the Board of Directors shall be sufficiently evidenced by a
      Board Resolution;

            (3) whenever in the administration of this Indenture the Trustee
      shall deem it desirable that a matter be proved or established prior to
      taking, suffering or omitting any action hereunder, the Trustee (unless
      other evidence be herein specifically prescribed) may, in the absence of
      bad faith on its part, rely upon an Officers' Certificate;

            (4) the Trustee may consult with counsel and the
      written advice of such counsel or any Opinion of Counsel shall be full and
      complete authorization and protection in respect of any action taken,
      suffered or omitted by it hereunder in good faith and in reliance thereon;


                                      -46-
<PAGE>   54
            (5) the Trustee shall be under no obligation to exercise any of the
      rights or powers vested in it by this Indenture at the request or
      direction of any of the Holders pursuant to this Indenture, unless such
      Holders shall have offered to the Trustee reasonable security or indemnity
      against the costs, expenses and liabilities which might be incurred by it
      in compliance with such request or direction;

            (6) the 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,
      warrant or other paper or document, but the Trustee, in its discretion,
      may make such further inquiry or investigation into such facts or matters
      as it may see fit, and, if the Trustee shall determine to make such
      further inquiry or investigation, it shall be entitled to examine the
      books, records and premises of the Company, personally or by agent or
      attorney;

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

            (8) the Trustee shall not be liable for any action taken, suffered
      or omitted by it in good faith and believed by it to be authorized or
      within the discretion or rights or powers conferred upon it by this
      Indenture; and

            (9) except during the continuance of an Event of Default, the
      Trustee need perform only these duties as are specifically set forth in
      this Indenture.

     The Trustee shall not be required to expend or risk its own funds or
otherwise incur any financial liability in the performance of any of its duties
hereunder, or in the exercise of any of its rights or powers if it shall have
reasonable grounds for believing that repayment of such funds or adequate
indemnity against such risk or liability is not reasonably assured to it.

      In the event that an Event of Default has occurred and is continuing, the
Trustee shall, in the exercise of its power, use the degree of care of a prudent
person in similar circumstances in the conduct of his or her own affairs.

SECTION 604.   Not Responsible for Recitals or Issuance of Securities.

      The recitals contained herein and in the Securities, except the Trustee's
certificates of authentication, shall be taken as the statements of the Company,
and neither the Trustee nor any Authenticating Agent assumes any responsibility
for their correctness. The Trustee makes no representations as to the validity
or sufficiency of this Indenture or of the Securities. Neither the Trustee


                                      -47-
<PAGE>   55
nor any Authenticating Agent shall be accountable for the use or application by
the Company of Securities or the proceeds thereof.

SECTION 605.   May Hold Securities.

      The Trustee, any Authenticating Agent, any Paying Agent, any Security
Registrar or any other agent of the Company, in its individual or any other
capacity, may become the owner or pledgee of Securities and, subject to Sections
608 and 613, may otherwise deal with the Company with the same rights it would
have if it were not Trustee, Authenticating Agent, Paying Agent, Security
Registrar or such other agent.

SECTION 606.   Money or Warrant Property Held in Trust.

      Money or Warrant Property held by the Trustee in trust hereunder need not
be segregated from other funds, securities or other property except to the
extent required by law. The Trustee shall be under no liability for interest on
any money or Warrant Property received by it hereunder except as otherwise
agreed with the Company.

SECTION 607.   Compensation and Reimbursement.

      The Company agrees

            (1) to pay to the Trustee from time to time reasonable compensation
      for all services rendered by it hereunder (which compensation shall not be
      limited by any provision of law in regard to the compensation of a trustee
      of an express trust);

            (2) except as otherwise expressly provided herein, to reimburse the
      Trustee upon its request for all reasonable expenses, disbursements and
      advances incurred or made by the Trustee in accordance with any provision
      of this Indenture (including the reasonable compensation and the expenses
      and disbursements of its agents and counsel), except any such expense,
      disbursement or advance as may be attributable to its negligence or bad
      faith; and

            (3) to indemnify the Trustee for, and to hold it harmless against,
      any loss, liability or expense incurred without negligence or bad faith on
      its part, arising out of or in connection with the acceptance or
      administration of the trust or trusts hereunder, including the costs and
      expenses of enforcing this Indenture against the Company (including
      Section 607) and defending itself against any claim, whether asserted by
      any Holder or the Company, or liability in connection with the exercise or
      performance of any of its powers or duties hereunder.

      To secure the Company's payment obligations in this Section 607, the
Trustee shall have a lien prior to the Securities on all money or property held
or collected by the Trustee, except that held in trust to pay the principal
amount, premium, if any, or interest, if any, as the case may be, on particular
Securities.


                                      -48-
<PAGE>   56
      The Company's payment obligations pursuant to this Section 607 shall
survive the discharge of this Indenture.

      When the Trustee incurs expenses after the occurrence of a Default
specified in Section 501(5) or (6), the expenses are intended to constitute
expenses of administration under any applicable law.

SECTION 608.   Conflicting Interests.

      If the Trustee has or shall acquire a conflicting interest within the
meaning of the Trust Indenture Act, the Trustee shall either eliminate such
interest or resign, to the extent and in the manner provided by, and subject to
the provisions of, the Trust Indenture Act and this Indenture. To the extent
permitted by such Act, the Trustee shall not be deemed to have a conflicting
interest by virtue of being a trustee under this Indenture with respect to
Securities of more than one series, [or a trustee under - list here any prior
indentures between the Company and the Trustee that have not been satisfied and
discharged and that may be excluded by the provisio to Section 310(b)(1) of the
Trust Indenture Act].

SECTION 609.   Corporate Trustee Required; Eligibility.

      There shall at all times be one (and only one) Trustee hereunder with
respect to the Securities of each series, which may be Trustee hereunder for
Securities of one or more other series. Each Trustee shall be a Person that is
eligible pursuant to the Trust Indenture Act to act as such, has a combined
capital and surplus of at least $50,000,000 and has its Corporate Trust Office
in the Borough of Manhattan, The City of New York. If any such Person publishes
reports of condition at least annually, pursuant to law or to the requirements
of its supervising or examining authority, then for the purposes of this Section
and to the extent permitted by the Trust Indenture Act, the combined capital and
surplus of such Person shall be deemed to be its combined capital and surplus as
set forth in its most recent report of condition so published. If at any time
the Trustee with respect to the Securities of any series shall cease to be
eligible in accordance with the provisions of this Section, it shall resign
immediately in the manner and with the effect hereinafter specified in this
Article.

SECTION 610.   Resignation and Removal; Appointment of Successor.

      No resignation or removal of the Trustee and no appointment of a successor
Trustee pursuant to this Article shall become effective until the acceptance of
appointment by the successor Trustee in accordance with the applicable
requirements of Section 611.

      The Trustee may resign at any time with respect to the Securities of one
or more series by giving written notice thereof to the Company. If the
instrument of acceptance by a successor Trustee required by Section 611 shall
not have been delivered to the Trustee within 30 days after the giving of such
notice of resignation, the resigning Trustee may petition any court of competent
jurisdiction for the appointment of a successor Trustee with respect to the
Securities of such series.

      The Trustee may be removed at any time with respect to the Securities of
any series by Act of the Holders of a majority in number of the Outstanding
Warrants of such series, delivered to the Trustee


                                      -49-
<PAGE>   57
and to the Company.

      If at any time:

            (1) the Trustee shall fail to comply with Section 608 after written
      request therefor by the Company or by any Holder who has been a bona fide
      Holder of a Security for at least six months, or

            (2) the Trustee shall cease to be eligible under Section 609 and
      shall fail to resign after written request therefor by the Company or by
      any such Holder, or

            (3) the Trustee shall become incapable of acting or shall be
      adjudged a bankrupt or insolvent or a receiver of the Trustee or of its
      property shall be appointed or any public officer shall take charge or
      control of the Trustee or of its property or affairs for the purpose of
      rehabilitation, conservation or liquidation,

then, in any such case, (A) the Company by a Board Resolution may remove the
Trustee with respect to all Securities, or (B) subject to Section 513, any
Holder who has been a bona fide Holder of a Security for at least six months
may, on behalf of himself and all others similarly situated, petition any court
of competent jurisdiction for the removal of the Trustee with respect to all
Securities and the appointment of a successor Trustee or Trustees.

      If the Trustee shall resign, be removed or become incapable of acting, or
if a vacancy shall occur in the office of Trustee for any cause, with respect to
the Securities of one or more series, the Company, by a Board Resolution, shall
promptly appoint a successor Trustee or Trustees with respect to the Securities
of that or those series (it being understood that any such successor Trustee may
be appointed with respect to the Securities of one or more or all of such series
and that at any time there shall be only one Trustee with respect to the
Securities of any particular series) and shall comply with the applicable
requirements of Section 611. If, within one year after such resignation, removal
or incapability, or the occurrence of such vacancy, a successor Trustee with
respect to the Securities of any series shall be appointed by Act of the Holders
of a majority in number of the Outstanding Warrants of such series delivered to
the Company and the retiring Trustee, the successor Trustee so appointed shall,
forthwith upon its acceptance of such appointment in accordance with the
applicable requirements of Section 611, become the successor Trustee with
respect to the Securities of such series and to that extent supersede the
successor Trustee appointed by the Company. If no successor Trustee with respect
to the Securities of any series shall have been so appointed by the Company or
the Holders and accepted appointment in the manner required by Section 611, any
Holder who has been a bona fide Holder of a Security of such series for at least
six months may, on behalf of himself and all others similarly situated, petition
any court of competent jurisdiction for the appointment of a successor Trustee
with respect to the Securities of such series.

      The Company shall give notice of each resignation and each removal of the
Trustee with respect to the Securities


                                      -50-
<PAGE>   58
of any series and each appointment of a successor Trustee with respect to the
Securities of any series to all Holders of Securities of such series in the
manner provided in Section 106. Each notice shall include the name of the
successor Trustee with respect to the Securities of such series and the address
of its Corporate Trust Office.

SECTION 611.   Acceptance of Appointment by Successor.

      In case of the appointment hereunder of a successor Trustee with respect
to all Securities, every such successor Trustee so appointed shall execute,
acknowledge and deliver to the Company and to the retiring Trustee an instrument
accepting such appointment, and thereupon the resignation or removal of the
retiring Trustee shall become effective and such successor Trustee, without any
further act, deed or conveyance, shall become vested with all the rights,
powers, trusts and duties of the retiring Trustee; but, on the request of the
Company or the successor Trustee, such retiring Trustee shall, upon payment of
its charges, execute and deliver an instrument transferring to such successor
Trustee all the rights, powers and trusts of the retiring Trustee and shall duly
assign, transfer and deliver to such successor Trustee all money, Warrant
Property and other property held by such retiring Trustee hereunder.

      In case of the appointment hereunder of a successor Trustee with respect
to the Securities of one or more (but not all) series, the Company, the retiring
Trustee and each successor Trustee with respect to the Securities of one or more
series shall execute and deliver an indenture supplemental hereto wherein each
successor Trustee shall accept such appointment and which (1) shall contain such
provisions as shall be necessary or desirable to transfer and confirm to, and to
vest in, each successor Trustee all the rights, powers, trusts and duties of the
retiring Trustee with respect to the Securities of that or those series to which
the appointment of such successor Trustee relates, (2) if the retiring Trustee
is not retiring with respect to all Securities, shall contain such provisions as
shall be deemed necessary or desirable to confirm that all the rights, powers,
trusts and duties of the retiring Trustee with respect to the Securities of that
or those series as to which the retiring Trustee is not retiring shall continue
to be vested in the retiring Trustee, and (3) shall add to or change any of the
provisions of this Indenture as shall be necessary to provide for or facilitate
the administration of the trusts hereunder by more than one Trustee, it being
understood that nothing herein or in such supplemental indenture shall
constitute such Trustees co-trustees of the same trust and that each such
Trustee shall be trustee of a trust or trusts hereunder separate and apart from
any trust or trusts hereunder administered by any other such Trustee; and upon
the execution and delivery of such supplemental indenture the resignation or
removal of the retiring Trustee shall become effective to the extent provided
therein and each such successor Trustee, without any further act, deed or
conveyance, shall become vested with all the rights, powers, trusts and duties
of the retiring Trustee with respect to the Securities of that or those series
to which the appointment of such successor Trustee relates; but, on request of
the Company or any successor Trustee, such retiring Trustee shall duly assign,
transfer and deliver to such successor Trustee all money, Warrant Property and
other property held by such retiring Trustee hereunder with respect to the
Securities of that or those series to which the appointment of such successor
Trustee relates.

      Upon request of any such successor Trustee, the Company shall execute any
and all instruments for more fully and certainly vesting in and confirming to
such successor Trustee all such rights, powers and trusts referred to in the
first or second preceding paragraph, as the case may be.

      No successor Trustee shall accept its appointment unless at the time of
such acceptance such successor Trustee shall be qualified and eligible under
this Article.


                                      -51-
<PAGE>   59
SECTION 612.   Merger, Conversion, Consolidation or Succession to Business.

      Any corporation into which the Trustee may be merged or converted or with
which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to all or substantially all the corporate trust business
of the Trustee, shall be the successor of the Trustee hereunder, provided such
corporation shall be otherwise qualified and eligible under this Article,
without the execution or filing of any paper or any further act on the part of
any of the parties hereto. In case any Securities shall have been authenticated,
but not delivered, by the Trustee then in office, any successor by merger,
conversion or consolidation to such authenticating Trustee may adopt such
authentication and deliver the Securities so authenticated with the same effect
as if such successor Trustee had itself authenticated such Securities.

SECTION 613.   Preferential Collection of Claims Against Company.

      If and when the Trustee shall be or become a creditor of the Company (or
any other obligor upon the Securities), the Trustee shall be subject to the
provisions of the Trust Indenture Act regarding the collection of claims against
the Company (or any such other obligor).

SECTION 614.   Appointment of Authenticating Agent.

      The Trustee may appoint an Authenticating Agent or Agents with respect to
one or more series of Securities which shall be authorized to act on behalf of
the Trustee to authenticate Securities of such series issued upon original issue
and upon exchange, registration of transfer or partial redemption thereof or
pursuant to Section 306, and Securities so authenticated shall be entitled to
the benefits of this Indenture and shall be valid and obligatory for all
purposes as if authenticated by the Trustee hereunder. Wherever reference is
made in this Indenture to the authentication and delivery of Securities by the
Trustee or the Trustee's certificate of authentication, such reference shall be
deemed to include authentication and delivery on behalf of the Trustee by an
Authenticating Agent and a certificate of authentication executed on behalf of
the Trustee by an Authenticating Agent. Each Authenticating Agent shall be
acceptable to the Company and shall at all times be a corporation organized and
doing business under the laws of the United States of America, any State thereof
or the District of Columbia, authorized under such laws to act as Authenticating
Agent, having a combined capital and surplus of not less than $50,000,000 and
subject to supervision or examination by Federal or State authority. If such
Authenticating Agent publishes reports of condition at least annually, pursuant
to law or to the requirements of said supervising or examining authority, then
for the purposes of this Section, the combined capital and surplus of such
Authenticating Agent shall be deemed to be its combined capital and surplus as
set forth in its most recent report of condition so published. If at any time an
Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section, such Authenticating Agent shall resign immediately
in the manner and with the effect specified in this Section.

      Any corporation into which an Authenticating Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which such Authenticating Agent
shall be a party, or any corporation succeeding to the corporate agency or
corporate trust business of an Authenticating Agent, shall continue to be an
Authenticating Agent, provided such corporation shall be otherwise eligible
under this Section, without the execution or filing of any paper or any further
act on the part of the Trustee or the Authenticating Agent.


                                      -52-
<PAGE>   60
      An Authenticating Agent may resign at any time by giving written notice
thereof to the Trustee and to the Company. The Trustee may at any time terminate
the agency of an Authenticating Agent by giving written notice thereof to such
Authenticating Agent and to the Company. Upon receiving such a notice of
resignation or upon such a termination, or in case at any time such
Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section, the Trustee may appoint a successor Authenticating
Agent which shall be acceptable to the Company and shall give notice of such
appointment in the manner provided in Section 106 to all Holders of Securities
of the series with respect to which such Authenticating Agent will serve. Any
successor Authenticating Agent upon acceptance of its appointment hereunder
shall become vested with all the rights, powers and duties of its predecessor
hereunder, with like effect as if originally named as an Authenticating Agent.
No successor Authenticating Agent shall be appointed unless eligible under the
provisions of this Section.

      The Trustee agrees to pay to each Authenticating Agent from time to time
reasonable compensation for its services under this Section, and the Trustee
shall be entitled to be reimbursed for such payments, subject to the provisions
of Section 607.

      If an appointment with respect to one or more series is made pursuant to
this Section, the Securities of such series may have endorsed thereon, in
addition to the Trustee's certificate of authentication, an alternative
certificate of authentication in the following form:

      This is one of the Securities of the series designated therein referred to
in the within-mentioned Indenture.

                                          -------------------------------------
                                                                      As Trustee

                                        By                                     ,
                                          -------------------------------------,
                                                         As Authenticating Agent

                                        By
                                           -------------------------------------
                                                              Authorized Officer


                                      -53-
<PAGE>   61
                                  ARTICLE SEVEN

                 HOLDERS' LISTS AND REPORTS BY TRUSTEE AND COMPANY

SECTION 701.   Company to Furnish Trustee Names and Addresses of Holders.

      The Company will furnish or cause to be furnished to the Trustee

            (1) semi-annually, not later than May 15 and November 15 in each
      year, a list, in such form as the Trustee may reasonably require, of the
      names and addresses of the Holders of Securities of each series as of the
      preceding May 1 or November 1, as the case may be, and

            (2) at such other times as the Trustee may request in writing,
      within 30 days after the receipt by the Company of any such request, a
      list of similar form and content as of a date not more than 15 days prior
      to the time such list is furnished;

excluding from any such list names and addresses received by the Trustee in its
capacity as Security Registrar.

SECTION 702.   Preservation of Information; Communications to Holders.

      The Trustee shall preserve, in as current a form as is reasonably
practicable, the names and addresses of Holders contained in the most recent
list furnished to the Trustee as provided in Section 701 and the names and
addresses of Holders received by the Trustee in its capacity as Security
Registrar. The Trustee may destroy any list furnished to it as provided in
Section 701 upon receipt of a new list so furnished.

      The rights of Holders to communicate with other Holders with respect to
their rights under this Indenture or under the Securities, and the corresponding
rights and privileges of the Trustee, shall be as provided by the Trust
Indenture Act.

      Every Holder of Securities, by receiving and holding the same, agrees with
the Company and the Trustee that neither the Company nor the Trustee nor any
agent of either of them shall be held accountable by reason of any disclosure of
information as to names and addresses of Holders made pursuant to the Trust
Indenture Act.

SECTION 703.   Reports by Trustee.

      The Trustee shall transmit to Holders such reports concerning the Trustee
and its actions under this Indenture as may be required pursuant to the Trust
Indenture Act at the times and in the manner provided pursuant thereto.

      Reports so required to be transmitted at stated intervals of not more than
12 months shall be transmitted no later than May 15 in each calendar year,
commencing in 2002.

      A copy of each such report shall, at the time of such transmission to
Holders, be filed by the Trustee with each stock exchange upon which any
Securities are listed, with the Commission and with


                                      -54-
<PAGE>   62
the Company. The Company will notify the Trustee when any Securities are listed
on any stock exchange.

SECTION 704.   Reports by Company.

      The Company shall file with the Trustee and the Commission, and transmit
to Holders, such information, documents and other reports, and such summaries
thereof, as may be required pursuant to the Trust Indenture Act at the times and
in the manner provided pursuant to such Act; provided that any such information,
documents or reports required to be filed with the Commission pursuant to
Section 13 or 15(d) of the Exchange Act shall be filed with the Trustee within
15 days after the same is so required to be filed with the Commission.


                                      -55-
<PAGE>   63
                                  ARTICLE EIGHT

                CONSOLIDATION, MERGER, CONVEYANCE, TRANSFER OR LEASE

SECTION 801.   Company May Consolidate, Etc., Only on Certain Terms.

      The Company 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 the Company shall not permit any Person to consolidate with
or merge into the Company or convey, transfer or lease its properties and assets
substantially as an entirety to the Company, unless:

            (1) in case the Company 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 Company is merged or the Person which
      acquires by conveyance or transfer, or which leases, the properties and
      assets of the Company substantially as an entirety shall be a corporation,
      partnership or trust, shall be organized and validly existing under the
      laws of Switzerland and shall expressly assume,
      by an indenture supplemental hereto, executed and delivered to the
      Trustee, in form satisfactory to the Trustee, the due and punctual payment
      or delivery of the money or Warrant Property payable or deliverable by the
      Company with respect to all the Securities in accordance with their terms
      and the performance or observance of every covenant of this Indenture on
      the part of the Company to be performed or observed and shall have
      provided for the right to exercise each Security in accordance with its
      terms;

            (2) immediately after giving effect to such transaction and treating
      any indebtedness which becomes an obligation of the Company or any
      Subsidiary as a result of such transaction as having been incurred by the
      Company or such Subsidiary at the time of such transaction, 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) if, as a result of any such consolidation or merger or such
      conveyance, transfer or lease, properties or assets of the Company would
      become subject to a mortgage, pledge, lien, security interest or other
      encumbrance which would not be permitted by this Indenture, the Company or
      such successor Person, as the case may be, shall take such steps as shall
      be necessary effectively to secure the Securities equally and ratably with
      (or prior to) all indebtedness or contractual obligations secured thereby;
      and

            (4) the Company has delivered to the Trustee an Officers'
      Certificate and an Opinion of Counsel, each stating that such
      consolidation, merger, conveyance, transfer or lease and, if a
      supplemental indenture is required in connection with such transaction,
      such supplemental indenture comply with this Article and that all
      conditions precedent herein provided for relating to such transaction have
      been complied with.

SECTION 802.   Successor Substituted.

      Upon any consolidation of the Company with, or merger of the Company into,
any other Person or any conveyance, transfer or lease of the properties and
assets of the Company substantially as an entirety in accordance with Section
801, the successor Person formed by such consolidation or into


                                      -56-
<PAGE>   64
which the Company 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 Company under this Indenture with the same effect as if such
successor Person had been named as the Company herein, and thereafter, except in
the case of a lease, the predecessor Person shall be relieved of all obligations
and covenants under this Indenture and the Securities.


                                      -57-
<PAGE>   65
                                  ARTICLE NINE

                             SUPPLEMENTAL INDENTURES

SECTION 901.   Supplemental Indentures Without Consent of Holders.

      Without the consent of any Holders, the Company, when authorized by a
Board Resolution, and the Trustee, at any time and from time to time, may enter
into one or more indentures supplemental hereto, in form satisfactory to the
Trustee, for any of the following purposes:

            (1) to evidence the succession of another Person to the Company and
      the assumption by any such successor of the covenants of the Company
      herein and in the Securities; or

            (2) to add to the covenants of the Company for the benefit of the
      Holders of all or any series of Securities (and if such covenants are to
      be for the benefit of less than all series of Securities, stating that
      such covenants are expressly being included solely for the benefit of such
      series) or to surrender any right or power herein conferred upon the
      Company; or

            (3) to add any additional Events of Default for the benefit of the
      Holders of all or any series of Securities (and if such additional Events
      of Default are to be for the benefit of less than all series of
      Securities, stating that such additional Events of Default are expressly
      being included solely for the benefit of such series); or

            (4) to add to or change any of the provisions of this Indenture to
      such extent as shall be necessary to permit or facilitate the issuance of
      Securities in bearer form, registrable or not registrable, or to permit or
      facilitate the issuance of Securities in uncertificated form; or

            (5) to add to, change or eliminate any of the provisions of this
      Indenture in respect of one or more series of Securities, provided that
      any such addition, change or elimination (A) shall neither (i) apply to
      any Security of any series created prior to the execution of such
      supplemental indenture and entitled to the benefit of such provision nor
      (ii) modify the rights of the Holder of any such Security with respect to
      such provision or (B) shall become effective only when there is no such
      Security Outstanding; or

            (6) to secure the Securities; or

            (7) to establish the form or terms of Securities of any series as
      permitted by Sections 201 and 301; or

            (8) to evidence and provide for the acceptance of appointment
      hereunder by a successor Trustee with respect to the Securities of one or
      more series and to add to or change any of the provisions of this
      Indenture as shall be necessary to provide for or facilitate the
      administration of the trusts hereunder by more than one Trustee, pursuant
      to the requirements of Section 611; or

            (9) to add to or change any of the provisions of this Indenture with
      respect to any Securities that by their terms may be exercised for
      securities or other property other than Securities of the same series and
      of like tenor, in order to permit or facilitate the issuance,


                                      -58-
<PAGE>   66
      payment, settlement or exercise of such Securities; or

            (10) to cure any ambiguity, to correct or supplement any provision
      herein which may be defective or inconsistent with any other provision
      herein, or to make any other provisions with respect to matters or
      questions arising under this Indenture, provided that such action pursuant
      to this Clause (10) shall not adversely affect the interests of the
      Holders of Securities of any series in any material respect.

SECTION 902.   Supplemental Indentures With Consent of Holders.

      With the consent of the Holders of not less than 66-2/3% in number of the
Outstanding Warrants of each series affected by such supplemental indenture, by
Act of said Holders delivered to the Company and the Trustee, the Company, when
authorized by a Board Resolution, and the Trustee may enter into an indenture or
indentures supplemental hereto for the purpose of adding any provisions to or
changing in any manner or eliminating any of the provisions of this Indenture or
of modifying in any manner the rights of the Holders of Securities of such
series under this Indenture; provided, however, that no such supplemental
indenture shall, without the consent of the Holder of each Outstanding Security
affected thereby,

            (1) change the terms of any Security with respect to the Payment or
      Settlement Date or exercise price thereof, or reduce the amount of money
      or reduce the amount or change the kind of Warrant Property payable or
      deliverable upon the exercise thereof or any premium payable upon the
      redemption thereof, or change any Place of Payment where, or the coin or
      currency in which, any Security or any money payable or deliverable upon
      the exercise thereof is payable, or permit the Company to redeem any
      Security if, absent such supplemental indenture, the Company would not be
      permitted to do so, or impair the right to institute suit for the
      enforcement of any such payment or delivery on or after the Payment or
      Settlement Date (or, in the case of redemption, on or after the Redemption
      Date) thereof, or impair the Holder's right to exercise such Security on
      the terms provided therein, or

            (2) if any Security provides that the Holder may require the Company
      to repurchase such Security, impair such Holder's right to require
      repurchase of such Security on the terms provided therein, or

            (3) reduce the percentage in number of the Outstanding Warrants of
      any one or more series (considered separately or together as one class, as
      applicable), the consent of whose Holders is required for any such
      supplemental indenture, or the consent of whose Holders is required for
      any waiver (of compliance with certain provisions of this Indenture or
      certain defaults hereunder and their consequences) provided for in this
      Indenture, or

            (4) modify any of the provisions of this Section, Section 512 or
      Section 1008, except to increase any such percentage or to provide that
      certain other provisions of this Indenture cannot be modified or waived
      without the consent of the Holder of each Outstanding Security affected
      thereby; provided, however, that this clause shall not be deemed to
      require the consent of any Holder with respect to changes in the
      references to "the Trustee" and concomitant changes in this Section and
      Section 1008, or the deletion of this proviso, in accordance with the
      requirements of Sections 611 and 901(8).


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<PAGE>   67
A supplemental indenture which changes or eliminates any covenant or other
provision of this Indenture which has expressly been included solely for the
benefit of one or more particular series of Securities, or which modifies the
rights of the Holders of Securities of such series with respect to such covenant
or other provision, shall be deemed not to affect the rights under this
Indenture of the Holders of Securities of any other series.

      It shall not be necessary for any Act of Holders under this Section to
approve the particular form of any proposed supplemental indenture, but it shall
be sufficient if such Act shall approve the substance thereof.

SECTION 903.   Execution of Supplemental Indentures.

      In executing, or accepting the additional trusts created by, any
supplemental indenture permitted by this Article or the modifications thereby of
the trusts created by this Indenture, the Trustee shall be entitled to receive,
and (subject to Section 601) shall be fully protected in relying upon, an
Opinion of Counsel stating that the execution of such supplemental indenture is
authorized or permitted by this Indenture. The Trustee may, but shall not be
obligated to, enter into any such supplemental indenture which affects the
Trustee's own rights, duties or immunities under this Indenture or otherwise.

SECTION 904.   Effect of Supplemental Indentures.

      Upon the execution of any supplemental indenture under this Article, this
Indenture shall be modified in accordance therewith, and such supplemental
indenture shall form a part of this Indenture for all purposes; and every Holder
of Securities theretofore or thereafter authenticated and delivered hereunder
shall be bound thereby.

SECTION 905.   Conformity with Trust Indenture Act.

      Every supplemental indenture executed pursuant to this Article shall
conform to the requirements of the Trust Indenture Act.

SECTION 906.   Reference in Securities to Supplemental Indentures.

      Securities of any series authenticated and delivered after the execution
of any supplemental indenture pursuant to this Article may, and shall if
required by the Trustee, bear a notation in form approved by the Trustee as to
any matter provided for in such supplemental indenture. If the Company shall so
determine, new Securities of any series so modified as to conform, in the
opinion of the Trustee and the Company, to any such supplemental indenture may
be prepared and executed by the Company and authenticated and delivered by the
Trustee in exchange for Outstanding Securities of such series.


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                                   ARTICLE TEN

                                    COVENANTS

SECTION 1001.  Payment or Delivery of Money or Warrant Property.

      The Company covenants and agrees for the benefit of each series of
Securities that it will duly and punctually pay or deliver the money or Warrant
Property payable or deliverable by the Company with respect to the Securities of
that series in accordance with the terms of the Securities and this Indenture.

SECTION 1002.  Maintenance of Office or Agency.

      Subject to the last paragraph of this section, the Company will maintain
in each Place of Payment for any series of Securities an office or agency where
Securities of that series may be presented or surrendered for payment, where
Securities of that series may be surrendered for registration of transfer or
exchange, where Securities may be surrendered upon exercise and where notices
and demands to or upon the Company in respect of the Securities of that series
and this Indenture may be served. The Company will give prompt written notice to
the Trustee of the location, and any change in the location, of such office or
agency. If at any time the Company shall fail to maintain any such required
office or agency or shall fail to furnish the Trustee with the address thereof,
such presentations, surrenders, notices and demands may be made or served at the
Corporate Trust Office of the Trustee, and the Company hereby appoints the
Trustee as its agent to receive all such presentations, surrenders, notices and
demands.

      The Company may also from time to time designate one or more other offices
or agencies where the Securities of one or more series may be presented or
surrendered for any or all such purposes and may from time to time rescind such
designations; provided, however, that no such designation or rescission shall in
any manner relieve the Company of its obligation pursuant to the first sentence
of the preceding paragraph to maintain an office or agency in each Place of
Payment for Securities of any series for such purposes. The Company will give
prompt written notice to the Trustee of any such designation or rescission and
of any change in the location of any such other office or agency.

      With respect to any Global Security, and except as otherwise may be
specified for such Global Security as contemplated by Section 301, the Corporate
Trust Office of the Trustee shall be the Place of Payment where such Global
Security may be presented or surrendered for exercise, payment or delivery of
money or Warrant Property due with respect to such Security or registration of
transfer or exchange, or where successor Securities may be delivered in exchange
therefor, provided, however, that any such payment, delivery, presentation or
surrender effected pursuant to the Applicable Procedures of the Depositary for
such Global Security shall be deemed to have been effected at the Place of
Payment for such Global Security in accordance with the provisions of this
Indenture.

SECTION 1003.  Money and Warrant Property for Securities Payments and Deliveries
               to Be Held in Trust.

      If the Company shall at any time act as its own Paying Agent with respect
to any series of Securities, it will, on or before the Payment or Settlement
Date of the Securities of that series, segregate


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<PAGE>   69
and hold in trust for the benefit of the Persons entitled thereto money or
Warrant Property sufficient to pay or deliver the money or Warrant Property
becoming due on such date until such sums or property shall be paid or delivered
to such Persons or otherwise disposed of as herein provided and will promptly
notify the Trustee of its action or failure so to act.

      Whenever the Company shall have one or more Paying Agents for any series
of Securities, it will, prior to the Payment or Settlement Date of the
Securities of that series, deposit with a Paying Agent money or Warrant Property
sufficient to pay or deliver the money or Warrant Property becoming due with
respect to such Securities on such date, such money or Warrant Property to be
held as provided by the Trust Indenture Act, and (unless such Paying Agent is
the Trustee) the Company will promptly notify the Trustee of its action or
failure so to act.

      The Company will cause each Paying Agent for any series of Securities
other than the Trustee to execute and deliver to the Trustee an instrument in
which such Paying Agent shall agree with the Trustee, subject to the provisions
of this Section, that such Paying Agent will (1) comply with the provisions of
the Trust Indenture Act applicable to it as a Paying Agent and (2) during the
continuance of any default by the Company (or any other obligor upon the
Securities of that series) in the making of any payment in respect of the
Securities of that series, upon the written request of the Trustee, forthwith
pay to the Trustee all money or Warrant Property held in trust by such Paying
Agent for payment in respect of the Securities of that series.

      The Company may at any time, for the purpose of obtaining the satisfaction
and discharge of this Indenture or for any other purpose, pay or deliver, or by
Company Order direct any Paying Agent to pay or deliver, to the Trustee all
money or Warrant Property held in trust by the Company or such Paying Agent,
such money or Warrant Property to be held by the Trustee upon the same trusts as
those upon which such money or Warrant Property were held by the Company or such
Paying Agent; and, upon such payment or delivery by any Paying Agent to the
Trustee, such Paying Agent shall be released from all further liability with
respect to such money or Warrant Property.

      Any money or Warrant Property deposited with the Trustee or any Paying
Agent, or then held by the Company, in trust for the payment or delivery of the
amounts due on any Security of any series in accordance with its terms and
remaining unclaimed for two years after such amounts have become due and payable
or deliverable shall be paid or delivered to the Company on Company Request, or
(if then held by the Company) shall be discharged from such trust; and the
Holder of such Security shall thereafter, as an unsecured general creditor, look
only to the Company for payment or delivery thereof, and all liability of the
Trustee or such Paying Agent with respect to such trust money or property, and
all liability of the Company as trustee thereof, shall thereupon cease.


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<PAGE>   70
SECTION 1004.  Statement by Officers as to Default.

      The Company will deliver to the Trustee, within 120 days after the end of
each fiscal year of the Company ending after the date hereof, an Officers'
Certificate, stating whether or not to the best knowledge of the signers thereof
the Company is in default in the performance and observance of any of the terms,
provisions and conditions of this Indenture (without regard to any period of
grace or requirement of notice provided hereunder) and, if the Company shall be
in default, specifying all such defaults and the nature and status thereof of
which they may have knowledge.

SECTION 1005.  Existence.

      Subject to Article Eight, the Company will do or cause to be done all
things necessary to preserve and keep in full force and effect its existence,
rights (charter and statutory) and franchises; provided, however, that the
Company shall not be required to preserve any such right or franchise if the
Board of Directors shall determine that the preservation thereof is no longer
desirable in the conduct of the business of the Company and that the loss
thereof is not disadvantageous in any material respect to the Holders.

SECTION 1006.  Payment of Taxes and Other Claims.

      The Company will pay or discharge or cause to be paid or discharged,
before the same shall become delinquent, (1) all taxes, assessments and
governmental charges levied or imposed upon the Company or any Subsidiary or
upon the income, profits or property of the Company or any Subsidiary, and (2)
all lawful claims for labor, materials and supplies which, if unpaid, might by
law become a lien upon the property of the Company or any Subsidiary; provided,
however, that the Company shall not be required to pay or discharge or cause to
be paid or discharged any such tax, assessment, charge or claim whose amount,
applicability or validity is being contested in good faith by appropriate
proceedings.

SECTION 1007.  Payment of Additional Amounts.

      Payments under the Securities will be made without deduction or
withholding for or on account of any present or future tax, duty, assessment or
governmental charge imposed upon or as a result of such payments by Switzerland
or any jurisdiction in which a branch of the Company through which any Security
is issued is located (or any political subdivision or taxing authority thereof
or therein) (a "Relevant Jurisdiction") ("Taxes"), unless required by law. To
the extent any such Taxes are so levied or imposed, the Company will, subject to
the exceptions and limitations set forth below, pay such additional amounts
("Additional Amounts") to the Holder of any Security who is not a resident of
the Relevant Jurisdiction or any political subdivision or taxing authority
thereof or therein as may be necessary in order that every net payment of the
principal of and interest on such Security and any other amounts payable on such
Security, after withholding for or on account of such Taxes imposed upon or as a
result of such payment, will not be less than the amount provided for in such
Security to be then due and payable. However, the Company will not be required
to make any payment of Additional Amounts to any such Holder if such payment can
be made without such deduction or withholding by a paying agent other than the
one required to make such a deduction or withholding. Further, the Company will
not be required to make any payment of Additional Amounts to any such Holder for
or on account of:

                  (i) any such Taxes which would not have been so imposed but
            for (a) the existence of any present or former connection between
            such Holder (or between a


                                      -63-
<PAGE>   71
            fiduciary, settler, beneficiary, member or shareholder of such
            Holder, if such Holder is an estate, a trust, a partnership or a
            corporation) and Switzerland (or any political subdivision or taxing
            authority thereof or therein) including, without limitation, such
            Holder (or such fiduciary, settler, beneficiary, member or
            shareholder) being or having been a citizen or resident thereof or
            being or having been engaged in a trade or business or present
            therein or having, or having had, a permanent establishment therein
            or (b) the presentation by or on behalf of the Holder of any such
            Security payment on a date more than 15 days after the date on which
            such payment became due and payable or the date on which payment
            thereof is duly provided for, whichever occurs later;

                  (ii) any estate, inheritance, gift, sales, transfer or
            personal property tax or any similar tax, duty, assessment or
            governmental charge;

                  (iii) any Taxes which are payable otherwise than by
            withholding from payments on or in respect of any Security;

                  (iv) any Taxes which would not have been imposed but for the
            failure to comply with certification, information or other reporting
            requirements concerning the nationality, residence or identity of
            the holder or beneficial owner of such Security, if such compliance
            is required by statute or by regulation of or on behalf of
            Switzerland or any political subdivision or taxing authority thereof
            or therein as a precondition to relief or exemption from such tax,
            assessment or other governmental charge; or

                  (v) any combination of items (i) through (iv) above;

nor shall Additional Amounts be paid with respect to any payment on a Security
to a Holder who is a fiduciary or partnership or other than the sole beneficial
owner of such payment to the extent such payment would be required to be
included in the income, for tax purposes, of a beneficiary or settlor with
respect to such fiduciary or a member of such partnership or a beneficial owner
who would not have been entitled to the Additional Amounts had such beneficiary,
settlor, member or beneficial owner been the Holder of the Security.

      The provisions of this Section 1007 shall also apply to any Taxes imposed
by any jurisdiction in which a Person into which the Company has merged or to
which the Company has conveyed, transferred or leased its property is located.

SECTION 1008.  Waiver of Certain Covenants.

      Except as otherwise specified as contemplated by Section 301 for
Securities of such series, the Company may, with respect to the Securities of
any series, omit in any particular instance to comply with any term, provision
or condition set forth in any covenant provided pursuant to Section 301(3),
901(2) or 901(7) for the benefit of the Holders of such series or in Article
Eight or Section 1008 if before the time for such compliance, the Holders of at
least a majority in number of the Outstanding Warrants of such series shall, by
Act of such Holders, either waive such compliance in such instance or generally
waive compliance with such term, provision or condition, but no such waiver
shall extend to or affect such term, provision or condition except to the extent
so expressly waived, and, until such waiver shall become effective, the
obligations of the Company and the


                                      -64-
<PAGE>   72
duties of the Trustee in respect of any such term, provision or condition shall
remain in full force and effect.


                                      -65-
<PAGE>   73
                                 ARTICLE ELEVEN

                            REDEMPTION OF SECURITIES

SECTION 1101.  Applicability of Article.

      Securities of any series which are redeemable before their Expiration Date
shall be redeemable in accordance with their terms and (except as otherwise
specified as contemplated by Section 301 for such Securities) in accordance with
this Article.

SECTION 1102.  Election to Redeem; Notice to Trustee.

      The election of the Company to redeem any Securities shall be evidenced by
a Board Resolution or in another manner specified as contemplated by Section 301
for such Securities. In case of any redemption at the election of the Company of
less than all the Securities of any series (including any such redemption
affecting only a single Security), the Company shall, at least 60 days prior to
the Redemption Date fixed by the Company (unless a shorter notice shall be
satisfactory to the Trustee), notify the Trustee of such Redemption Date and of
the number of Warrants of such series to be redeemed and, if applicable, the
tenor of the Warrants to be redeemed. In the case of any redemption of
Securities prior to the expiration of any restriction on such redemption
provided in the terms of such Securities or elsewhere in this Indenture, the
Company shall furnish the Trustee with an Officers' Certificate evidencing
compliance with such restriction.

SECTION 1103.  Selection by Trustee of Securities to Be Redeemed.

      If less than all the Securities of any series and of a specified tenor are
to be redeemed (unless all the Securities of such series and tenor are to be
redeemed or unless such redemption affects only a single Security), the
particular Securities to be redeemed shall be selected not more than 60 days
prior to the Redemption Date by the Trustee, from the Outstanding Securities of
such series not previously called for redemption, by such method as the Trustee
shall deem fair and appropriate, provided that the unredeemed portion of any
Security shall be in an authorized denomination (which shall not be less than
the minimum authorized denomination) for such Security. If less than all the
Securities of such series and of a specified tenor are to be redeemed (unless
such redemption affects only a single Security), the particular Securities to be
redeemed shall be selected not more than 60 days prior to the Redemption Date by
the Trustee, from the Outstanding Securities of such series and specified tenor
not previously called for redemption in accordance with the preceding sentence.

      If any Security selected for partial redemption is exercised in part
before termination of the exercise right with respect to the portion of the
Security so selected, the exercised portion of such Security shall be deemed (so
far as may be) to be the portion selected for redemption. Securities which have
been exercised during a selection of Securities to be redeemed shall be treated
by the Trustee as Outstanding for the purpose of such selection.

      The Trustee shall promptly notify the Company in writing of the Securities
selected for redemption as aforesaid and, in case of any Securities selected for
partial redemption as aforesaid, the amount thereof to be redeemed.


                                      -66-
<PAGE>   74
      The provisions of the two preceding paragraphs shall not apply with
respect to any redemption affecting only a single Security, whether such
Security is to be redeemed in whole or in part. In the case of any such
redemption in part, the unredeemed portion of the Security shall be in an
authorized denomination (which shall not be less than the minimum authorized
denomination) for such Security.

      For all purposes of this Indenture, unless the context otherwise requires,
all provisions relating to the redemption of Securities shall relate, in the
case of any Securities redeemed or to be redeemed only in part, to the portion
of such Securities which has been or is to be redeemed.

SECTION 1104.  Notice of Redemption.

      Notice of redemption shall be given by first-class mail, postage prepaid,
mailed not less than 10 nor more than 60 days prior to the Redemption Date, to
each Holder of Securities to be redeemed, at his address appearing in the
Security Register.

      All notices of redemption shall state:

            (1) the Redemption Date,

            (2) the Redemption Price,

            (3) if less than all the Outstanding Securities of any series
      consisting of more than a single Security are to be redeemed, the
      identification (and, in the case of partial redemption of any such
      Securities, the amounts) of the particular Securities to be redeemed and,
      if less than all the Outstanding Securities of any series consisting of a
      single Security are to be redeemed, the amount of the particular Security
      to be redeemed,

            (4) that on the Redemption Date the Redemption Price will become due
      and payable upon each such Security to be redeemed,

            (5) the place or places where each such Security is to be
      surrendered for payment of the Redemption Price, and

            (6) if applicable, the terms of exercise, the date on which the
      right to exercise the Security to be redeemed will terminate and the place
      or places where such Securities may be surrendered for exercise.

      Notice of redemption of Securities to be redeemed at the election of the
Company shall be given by the Company or, at the Company's request, by the
Trustee in the name and at the expense of the Company and shall be irrevocable.

SECTION 1105.  Deposit of Redemption Price.

      Prior to any Redemption Date, the Company shall deposit with the Trustee
or with a Paying Agent (or, if the Company is acting as its own Paying Agent,
segregate and hold in trust as provided in Section 1003) an amount of money
sufficient to pay the Redemption Price of all the Securities which are


                                      -67-
<PAGE>   75
to be redeemed on that date, other than any Securities called for redemption on
that date which have been exercised prior to the date of such deposit.

      If any Security called for redemption is exercised, any money deposited
with the Trustee or with any Paying Agent or so segregated and held in trust for
the redemption of such Security shall be paid to the Company upon Company
Request or, if then held by the Company, shall be discharged from such trust.

SECTION 1106.  Securities Payable on Redemption Date.

      Notice of redemption having been given as aforesaid, the Securities so to
be redeemed shall, on the Redemption Date, become due and payable at the
Redemption Price therein specified. Upon surrender of any such Security for
redemption in accordance with said notice, such Security shall be paid by the
Company at the Redemption Price.

SECTION 1107.  Securities Redeemed in Part.

      Any Security which is to be redeemed only in part shall be surrendered at
a Place of Payment therefor (with, if the Company or the Trustee so requires,
due endorsement by, or a written instrument of transfer in form satisfactory to
the Company and the Trustee duly executed by, the Holder thereof or his attorney
duly authorized in writing), and the Company shall execute, and the Trustee
shall authenticate and deliver to the Holder of such Security without service
charge, a new Security or Securities of the same series and of like tenor, of
any authorized denomination as requested by such Holder, in number equal to and
in exchange for the unredeemed portion of the Security so surrendered.

      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.

      IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed as of the day and year first above written.

                                    UBS AG

                                    By__________________________


                                    By__________________________

                                     [Trustee]

                                    By__________________________

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