Document:

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                                                                   EXHIBIT 10.29

                            WARRANT TO PURCHASE STOCK

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR THE SECURITIES LAWS OF
ANY STATE AND, EXCEPT AND PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW, MAY NOT
BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND
UNTIL REGISTERED UNDER SAID ACT AND APPLICABLE STATE SECURITIES LAW OR, IN THE
OPINION OF LEGAL COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER OF
THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS
EXEMPT FROM REGISTRATION.

Company:  ZHONE TECHNOLOGIES, INC., a Delaware corporation
Number of Shares: 138,614 shares
Class of Stock:  Series B Preferred
Warrant Price:  $2.02 per share
Issue Date:  December 30, 2002
Expiration Date: December 30, 2009

      THIS WARRANT CERTIFIES THAT, for the agreed upon value of $1.00 and for
other good and valuable consideration, SILICON VALLEY BANK ("Holder") is
entitled to purchase the number of fully paid and nonassessable shares of the
class of securities (the "Shares") of the company (the "Company") at the Warrant
Price, all as set forth above and as adjusted pursuant to Article 2 of this
Warrant, subject to the provisions and upon the terms and conditions set forth
in this Warrant.

ARTICLE 1. EXERCISE.

            1.1   Method of Exercise. Holder may exercise this Warrant by
delivering a duly executed Notice of Exercise in substantially the form attached
as Appendix 1 to the principal office of the Company. Unless Holder is
exercising the conversion right set forth in Article 1.2, Holder shall also
deliver to the Company a check, wire transfer (to an account designated by the
Company), or other from of payment acceptable to the Company for the aggregate
Warrant Price for the Shares being purchased.

            1.2   Conversion Right. In lieu of exercising this Warrant as
specified in Article 1.1, Holder may from time to time convert this Warrant, in
whole or in part, into a number of Shares determined by dividing (a) the
aggregate fair market value of the Shares or other securities otherwise issuable
upon exercise of this Warrant minus the aggregate Warrant Price of such Shares
by (b) the fair market value of one Share. The fair market value of the Shares
shall be determined pursuant to Article 1.3.

            1.3   Fair Market Value. If the Company's common stock is traded in
a public market and the shares are common stock, the fair market value of each
Share shall be the closing price of a Share reported for the business day
immediately before Holder delivers its Notice of Exercise to the Company (or in
the instance where the Warrant is exercised immediately prior to the
effectiveness of the Company's initial public offering, the "price to public"
per share price specified in the final prospectus relating to such offering). If
the Company's common stock is traded in a public market and the Shares are
preferred stock, the

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fair market value of a Share shall be the closing price of a share of the
Company's common stock reported for the business day immediately before Holder
delivers its Notice of Exercise to the Company (or, in the instance where the
Warrant is exercised immediately prior to the effectiveness of the Company's
initial public offering, the initial "price to public" per share price specified
in the final prospectus relating to such offering), in both cases, multiplied by
the number of shares of the Company's common stock into which a Share is
convertible. If the Company's common stock is not traded in a public market, the
Board of Directors of the Company shall determine fair market value in its
reasonable good faith judgment.

            1.4   Delivery of Certificate and New Warrant. Promptly after Holder
exercises or converts this Warrant and, if applicable, the Company receives
payment of the aggregate Warrant Price, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the
Shares not so acquired.

            1.5   Replacement of Warrants. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, or surrender and cancellation of this Warrant,
the Company shall execute and deliver, in lieu of this Warrant, a new warrant of
like tenor.

            1.6   Treatment of Warrant Upon Acquisition of Company.

                  1.6.1 "Acquisition". For the purpose of this Warrant,
"Acquisition" means any sale, license, or other disposition of all or
substantially all of the assets of the Company, or any reorganization,
consolidation, or merger of the Company where the holders of the Company's
securities before the transaction beneficially own less than 50% of the
outstanding voting securities of the surviving entity after the transaction.

                  1.6.2 Treatment of Warrant at Acquisition.

A)    Upon the written request of the Company, Holder agrees that, in the event
of an Acquisition in which the sole consideration is cash, either (a) Holder
shall exercise its conversion or purchase right under this Warrant and such
exercise will be deemed effective immediately prior to the consummation of such
Acquisition or (b) if Holder elects not to exercise the Warrant, this Warrant
will expire upon the consummation of such Acquisition. The Company shall provide
the Holder with written notice of its request relating to the foregoing
(together with such information as the Holder may reasonably request in
connection with such contemplated Acquisition giving rise to such notice), which
is to be delivered to Holder not less than ten (10) days prior to the closing of
the proposed Acquisition.

B)    Upon the written request of the Company, Holder agrees that, in the event
of an "arms length" sale of all or substantially all of the Company's assets
(and only its assets) to a third party that is not an Affiliate (as defined
below) of the Company (a "True Asset Sale"), either (a) Holder shall exercise
its conversion or purchase right under this Warrant and such exercise will be
deemed effective immediately prior to the consummation of such True Asset Sale
or (b) if Holder elects not to exercise the Warrant, this Warrant will continue
until the Expiration Date if the Company continues as a going concern following
the closing of any such True Asset Sale. The Company shall provide the Holder
with written notice of its request relating to the foregoing (together with such
information as the Holder may reasonably request in connection with such

                                       -2-

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contemplated True Asset Sale giving rise to such notice), which is to be
delivered to Holder not less than ten (10) days prior to the closing of the
proposed True Asset Sale .

C)    Upon the closing of any Acquisition other than those particularly
described in subsections (A) and (B) above, the successor entity shall assume
the obligations of this Warrant, and this Warrant shall be exercisable for the
same securities, cash, and property as would be payable for the Shares issuable
upon exercise of the unexercised portion of this Warrant as if such Shares were
outstanding on the record date for the Acquisition and subsequent closing. The
Warrant Price and/or number of Shares shall be adjusted accordingly.

As used herein "Affiliate" shall mean any person or entity that owns or controls
directly or indirectly ten (10) percent or more of the stock of Company, any
person or entity that controls or is controlled by or is under common control
with such persons or entities, and each of such person's or entity's officers,
directors, joint venturers or partners, as applicable.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

            2.1   Stock Dividends, Splits, Etc. If the Company declares or pays
a dividend on the Shares payable in common stock, or other securities, then upon
exercise of this Warrant, for each Share acquired, Holder shall receive, without
cost to Holder, the total number and kind of securities to which Holder would
have been entitled had Holder owned the Shares of record as of the date the
dividend occurred. If the Company subdivides the Shares by reclassification or
otherwise into a greater number of shares or takes any other action which
increase the amount of stock into which the Shares are convertible, the number
of shares purchasable hereunder shall be proportionately increased and the
Warrant Price shall be proportionately decreased. If the outstanding shares are
combined or consolidated, by reclassification or otherwise, into a lesser number
of shares, the Warrant Price shall be proportionately increased and the number
of Shares shall be proportionately decreased.

            2.2   Reclassification, Exchange, Combinations or Substitution. Upon
any reclassification, exchange, substitution, or other event that results in a
change of the number and/or class of the securities issuable upon exercise or
conversion of this Warrant, Holder shall be entitled to receive, upon exercise
or conversion of this Warrant, the number and kind of securities and property
that Holder would have received for the Shares if this Warrant had been
exercised immediately before such reclassification, exchange, substitution, or
other event. Such an event shall include any automatic conversion of the
outstanding or issuable securities of the Company of the same class or series as
the Shares to common stock pursuant to the terms of the Company's Articles or
Certificate (as applicable) of Incorporation upon the closing of a registered
public offering of the Company's common stock. The Company or its successor
shall promptly issue to Holder an amendment to this Warrant setting forth the
number and kind of such new securities or other property issuable upon exercise
or conversion of this Warrant as a result of such reclassification, exchange,
substitution or other event that results in a change of the number and/or class
of securities issuable upon exercise or conversion of this Warrant. The
amendment to this Warrant shall provide for adjustments which shall be as nearly
equivalent as may be practicable to the adjustments provided for in this Article
2 including, without limitation, adjustments to the Warrant Price and to the
number of securities or property issuable upon exercise of the new Warrant. The
provisions of this Article 2.2 shall similarly apply to successive
reclassifications, exchanges, substitutions, or other events.

                                       -3-

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            2.3   Adjustments for Diluting Issuances. The Warrant Price and the
number of Shares issuable upon exercise of this Warrant or, if the Shares are
Preferred Stock, the number of shares of common stock issuable upon conversion
of the Shares, shall be subject to adjustment, from time to time in the manner
set forth in the Company's Articles or Certificate of Incorporation as if the
Shares were issued and outstanding on and as of the date of any such required
adjustment. The provisions set forth for the Shares in the Company's Articles or
Certificate (as applicable) of Incorporation relating to the above in effect as
of the Issue Date may not be amended, modified or waived, without the prior
written consent of Holder unless such amendment, modification or waiver affects
the rights associated with the Shares in the same manner as such amendment,
modification or waiver affects the rights associated with all other shares of
the same series and class as the Shares granted to the Holder.

            2.4   No Impairment. The Company shall not, by amendment of its
Articles or Certificate (as applicable) of Incorporation or through a
reorganization, transfer of assets, consolidation, merger, dissolution, issue,
or sale of securities or any other voluntary action, avoid or seek to avoid the
observance or performance of any of the terms to be observed or performed under
this Warrant by the Company, but shall at all times in good faith assist in
carrying out of all the provisions of this Article 2 and in taking all such
action as may be necessary or appropriate to protect Holder's rights under this
Article against impairment.

            2.5   Fractional Shares. No fractional Shares shall be issuable upon
exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded down to the nearest whole Share. If a fractional share interest
arises upon any exercise or conversion of the Warrant, the Company shall
eliminate such fractional share interest by paying Holder the amount computed by
multiplying the fractional interest by the fair market value of a full Share.

            2.6   Certificate as to Adjustments. Upon each adjustment of the
Warrant Price, the Company shall promptly notify Holder in writing, and, at the
Company's expense, promptly compute such adjustment, and furnish Holder with a
certificate of its Vice President Finance and Treasurer setting forth such
adjustment and the facts upon which such adjustment is based. The Company shall,
upon written request, furnish Holder a certificate setting forth the Warrant
Price in effect upon the date thereof and the series of adjustments leading to
such Warrant Price.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

            3.1   Representations and Warranties. The Company represents and
warrants to the Holder as follows:

                  (a)   The initial Warrant Price referenced on the first page
of this Warrant is not greater than (i) the price per share at which the Shares
were last issued in an arms-length transaction in which at least $500,000 of the
Shares were sold and (ii) the fair market value of the Shares as of the date of
this Warrant.

                  (b)   All Shares which may be issued upon the exercise of the
purchase right represented by this Warrant, and all securities, if any, issuable
upon conversion of the Shares, shall, upon issuance, be duly authorized, validly
issued, fully paid and nonassessable, and free of any liens and encumbrances
except for restrictions on transfer provided for herein or under applicable
federal and state securities laws.

                                       -4-

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                  (c)   The Capitalization Table previously provided to Holder
remains true and complete as of the Issue Date.

            3.2   Notice of Certain Events. If the Company proposes at any time
(a) to declare any dividend or distribution upon any of its stock, whether in
cash, property, stock, or other securities and whether or not a regular cash
dividend; (b) to offer for subscription pro rata to the holders of any class or
series of its stock any additional shares of stock of any class or series or
other rights, or to issue any additional shares of its stock; (c) to effect any
reclassification or recapitalization of any of its stock; (d) to merge or
consolidate with or into any other corporation, or sell, lease, license, or
convey all or substantially all of its assets, or to liquidate, dissolve or wind
up; or (e) offer holders of registration rights the opportunity to participate
in an underwritten public offering of the company's securities for cash, then,
in connection with each such event, the Company shall give Holder: (1) at least
10 days prior written notice of the date on which a record will be taken for
such dividend, distribution, or subscription rights (and specifying the date on
which the holders of common stock will be entitled thereto) or for determining
rights to vote, if any, in respect of the matters referred to in (c) and (d)
above; (2) in the case of the matters referred to in (c) and (d) above at least
10 days prior written notice of the date when the same will take place (and
specifying the date on which the holders of common stock will be entitled to
exchange their common stock for securities or other property deliverable upon
the occurrence of such event); and (3) in the case of the matter referred to in
(e) above, the same notice as is given to the holders of such registration
rights.

            3.3   Registration Under the Act . The Company shall use its
reasonable efforts to cause the shares of common stock of the Company into which
the Shares are convertible to be subject to the registration rights provisions
set forth in the Company's Rights Agreement, dated as of July 1, 2002 (the
"Rights Agreement"). The provisions set forth in the Rights Agreement relating
to the above in effect as of the Issue Date may not be amended, modified or
waived without the prior written consent of Holder unless such amendment,
modification or waiver affects the rights associated with the Shares in the same
manner as such amendment, modification, or waiver affects the rights associated
with all other shares of the same series and class as the Shares granted to the
Holder. Until such time as the shares of common stock of the Company into which
the Shares are convertible are subject to the registration rights provisions set
forth in the Rights Agreement, the Company agrees that said shares shall have
the same registration rights as those provided for in the Rights Agreement, but
subject to such limitations as are reasonably necessary so that said
registration rights do not adversely affect the rights of "Holders" under the
Rights Agreement and comply with Section 1.11 of the Rights Agreement in effect
on the date hereof.

            3.4   No Shareholder Rights. Except as provided in this Warrant, the
Holder will not have any rights as a shareholder of the Company until the
exercise of this Warrant.

ARTICLE 4. REPRESENTATIONS, WARRANTIES OF THE HOLDER. The Holder represents and
warrants to the Company as follows:

            4.1   Purchase for Own Account. This Warrant and the securities to
be acquired upon exercise of this Warrant by the Holder will be acquired for
investment for the Holder's account, not as a nominee or agent, and not with a
view to the public resale or distribution within the meaning of the Act. Holder
also represents that the Holder has not been formed for the specific purpose of
acquiring this Warrant or the Shares.

                                       -5-

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            4.2   Disclosure of Information. The Holder has received or has had
full access to all the information it considers necessary or appropriate to make
an informed investment decision with respect to the acquisition of this Warrant
and its underlying securities. The Holder further has had an opportunity to ask
questions and receive answers from the Company regarding the terms and
conditions of the offering of this Warrant and its underlying securities and to
obtain additional information (to the extent the Company possessed such
information or could acquire it without unreasonable effort or expense)
necessary to verify any information furnished to the Holder or to which the
Holder has access.

            4.3   Investment Experience. The Holder understands that the
purchase of this Warrant and its underlying securities involves substantial
risk. The Holder has experience as an investor in securities of companies in the
development stage and acknowledges that the Holder can bear the economic risk of
such Holder's investment in this Warrant and its underlying securities and has
such knowledge and experience in financial or business matters that the Holder
is capable of evaluating the merits and risks of its investment in this Warrant
and its underlying securities and/or has a preexisting personal or business
relationship with the Company and certain of its officers, directors or
controlling persons of a nature and duration that enables the Holder to be aware
of the character, business acumen and financial circumstances of such persons.

            4.4   Accredited Investor Status. The Holder is an "accredited
investor" within the meaning of Regulation D promulgated under the Act.

            4.5   The Act. The Holder understands that this Warrant and the
Shares issuable upon exercise or conversion hereof have not been registered
under the Act in reliance upon a specific exemption therefrom, which exemption
depends upon, among other things, the bona fide nature of the Holder's
investment intent as expressed herein. The Holder understands that this Warrant
and the Shares issued upon any exercise or conversion hereof must be held
indefinitely unless subsequently registered under the 1933 Act and qualified
under applicable state securities laws, or unless exemption from such
registration and qualification are otherwise available.

            4.6   Market Stand-Off Agreement. Holder agrees to be bound by the
"Market Stand-Off" provision (the "Market Stand-Off Provision") in section 1.12
of the Rights Agreement. The Market Stand-Off Provision provisions set forth in
the Rights Agreement may not be amended, modified or waived without the prior
written consent of Holder unless such amendment, modification or waiver affects
the rights associated with the Shares in the same manner as such amendment,
modification, or waiver affects the rights associated with all other shares of
the same series and class as the of Shares granted pursuant to this Warrant.

ARTICLE 5. MISCELLANEOUS.

            5.1   Term: This Warrant is exercisable in whole or in part at any
time and from time to time on or before the Expiration Date.

            5.2   Legends. This Warrant and the Shares (and the securities
issuable, directly or indirectly, upon conversion of the Shares, if any) shall
be imprinted with a legend in substantially the following form:

            THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE

                                       -6-

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            NOT BEEN REGISTERED UNDER THE ACT, OR THE SECURITIES LAWS OF ANY
            STATE AND, EXCEPT AND PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW,
            MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR
            HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND
            APPLICABLE STATE SECURITIES LAW OR IN THE OPINION OF LEGAL COUNSEL
            IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER OF THESE
            SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS
            EXEMPT FROM REGISTRATION.

            5.3   Compliance with Securities Laws on Transfer. This Warrant and
the Shares issuable upon exercise of this Warrant (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) may not be
transferred or assigned in whole or in part without compliance with applicable
federal and state securities laws by the transferor and the transferee
(including, without limitation, the delivery of investment representation
letters and legal opinions reasonably satisfactory to the Company, as reasonably
requested by the Company). The Company shall not require Holder to provide an
opinion of counsel if the transfer is to Silicon Valley Bancshares (Holder's
parent company) or any other affiliate of Holder. Additionally, the Company
shall also not require an opinion of counsel if there is no material question as
to the availability of current information as referenced in Rule 144(c), Holder
represents that it has complied with Rule 144(d) and (e) in reasonable detail,
the selling broker represents that it has complied with Rule 144(f), and the
Company is provided with a copy of Holder's notice of proposed sale.

            5.4   Transfer Procedure. Upon receipt by Holder of the executed
Warrant, Holder will transfer all of this Warrant to Silicon Valley Bancshares,
Holder's parent company, by execution of an Assignment substantially in the form
of Appendix 2. Subject to the provisions of Section 5.3 and upon providing
Company with written notice, Silicon Valley Bancshares and any subsequent Holder
may transfer all or part of this Warrant or the Shares issuable upon exercise of
this Warrant (or the Shares issuable directly or indirectly, upon conversion of
the Shares, if any) to any transferee, provided, however, in connection with any
such transfer, Silicon Valley Bancshares or any subsequent Holder will give the
Company notice of the portion of the Warrant being transferred with the name,
address and taxpayer identification number of the transferee and Holder will
surrender this Warrant to the Company for reissuance to the transferee(s) (and
Holder if applicable). The Company may refuse to transfer this Warrant or the
Shares to any person who directly competes with the Company, unless, in either
case, the stock of the Company is publicly traded.

            5.5   Notices. All notices and other communications from the Company
to the Holder, or vice versa, shall be deemed delivered and effective when given
personally or mailed by first-class registered or certified mail, postage
prepaid, at such address as may have been furnished to the Company or the
Holder, as the case may (or on the first business day after transmission by
facsimile) be, in writing by the Company or such holder from time to time.
Effective upon receipt of the fully executed Warrant and the initial transfer
described in Article 5.4 above, all notices to the Holder shall be addressed as
follows until the Company receives notice of a change of address in connection
with a transfer or otherwise:

                  Silicon Valley Bancshares
                  Attn:  Treasury Department
                  3003 Tasman Drive, HA 200

                                       -7-

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                  Santa Clara, CA 95054
                  Telephone:  408-654-7400
                  Facsimile:  408-496-2405

      Notice to the Company shall be addressed as follows until the Holder
receives notice of a change in address:

                  Zhone Technologies, Inc.
                  7001 Oakport St.
                  Oakland, California  94621
                  Attn: Vice President Finance
                  Telephone: 510-777-7000
                  Facsimile:__________________

            5.6   Waiver. This Warrant and any term hereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought.

            5.7   Attorney's Fees. In the event of any dispute between the
parties concerning the terms and provisions of this Warrant, the party
prevailing in such dispute shall be entitled to collect from the other party all
costs incurred in such dispute, including reasonable attorney's fees.

            5.8   Automatic Conversion upon Expiration. In the event that, upon
the Expiration Date, the fair market value of one Share (or other security
issuable upon the exercise hereof) as determined in accordance with Section 1.3
above is greater than the Exercise Price in effect on such date, then this
Warrant shall automatically be deemed on and as of such date to be converted
pursuant to Section 1.2 above as to all Shares (or such other securities) for
which it shall not previously have been exercised or converted, and the Company
shall promptly deliver a certificate representing the Shares (or such other
securities) issued upon such conversion to the Holder.

            5.9   Counterparts. This Warrant may be executed in counterparts,
all of which together shall constitute one and the same agreement.

            5.10  Governing Law. This Warrant shall be governed by and construed
in accordance with the laws of the State of California, without giving effect to
its principles regarding conflicts of law.

                                       -8-

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"COMPANY"

Zhone Technologies, Inc.

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

Name:                                          Name:
     ---------------------------                    ---------------------------
       (Print)                                        (Print)
Title: Chairman of the Board, President or     Title: Chief Financial Officer,
       Vice President                                 Secretary, Assistant
                                                      Treasurer or Assistant
                                                      Secretary

"HOLDER"

Silicon Valley Bank

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

Name:
     ---------------------------
     (Print)
Title:
       ------------------
                                                                              -1

                                       -9-

<PAGE>

                                   APPENDIX 1

                               NOTICE OF EXERCISE

      1.    Holder elects to purchase ______ shares of the Common/Series
_______ Preferred [strike one] Stock of _______ pursuant to the terms of the
attached Warrant, and tenders payment of the purchase price of the shares in
full.

      [or]

      1.    Holder elects to convert the attached Warrant into Shares/cash
[strike one] in the manner specified in the Warrant. This conversion is
exercised for ______ of the Shares covered by the Warrant.

      [Strike paragraph that does not apply.]

      2.    Please issue a certificate or certificates representing the shares
in the name specified below:

                 -------------------------------------------
                          Holders Name

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

                 -------------------------------------------
                          (Address)

      3.    By its execution below and for the benefit of the Company, Holder
hereby restates each of the representations and warranties in Article 4 of the
Warrant as the date hereof.

                                               HOLDER:

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

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

                                               Name:
                                                    -------------------------

                                               Title:
                                                     -------------------------

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

                                      -10-

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                                   APPENDIX 2

                                   ASSIGNMENT

      For value received, Silicon Valley Bank hereby sells, assigns and
      transfers unto

                   Name:      Silicon Valley Bancshares
                   ADDRESS:   3003 Tasman Drive(HA-200)
                              Santa Clara, CA 95054

                   TAX ID:          91-1962278

      that certain Warrant to Purchase Stock issued by Zhone Technologies, Inc.
      (the "Company"), on December __ , 2002 (the "Warrant") together with all
      rights, title and interest therein.

                                           SILICON VALLEY BANK

                                           By:
                                              ----------------------------------
                                           Name:
                                                --------------------------------
                                           Title:
                                                 -------------------------------

Date: [insert Issue Date] ________________

By its execution below, and for the benefit of the Company, Silicon Valley
Bancshares makes each of the representations and warranties set forth in Article
4 of the Warrant as of the date hereof.

                                           SILICON VALLEY BANCSHARES

                                           By:
                                              ----------------------------------
                                           Name:
                                                --------------------------------
                                           Title:
                                                 -------------------------------

                                      -11-<PAGE>

                                                                  Exhibit 4.3(c)

                          AMENDMENT TO RIGHTS AGREEMENT

     This Amendment, dated as of January 1, 2003 (this "Amendment"), to the
Rights Agreement, dated as of March 28, 1991, as amended and restated as of
December 8, 2000 (the "Rights Agreement"), is among Cabot Oil & Gas Corporation,
a Delaware corporation (the "Company"), Fleet National Bank, formerly known as
The First National Bank of Boston and as BankBoston, N.A. (the "Former Rights
Agent"), and The Bank of New York (the "New Rights Agent").

     WHEREAS, the Company and the Former Rights Agent entered into the Rights
Agreement specifying the terms of the Rights (as defined therein);

     WHEREAS, the Former Rights Agent is resigning as Rights Agent and the
Company desires to appoint the New Rights Agent as successor Rights Agent;

     WHEREAS, the Company desires to amend the Rights Agreement in accordance
with Section 27 of the Rights Agreement to reflect the succession of the New
Rights Agent to the position of Rights Agent and make a related change to the
Rights Agreement;

     NOW, THEREFORE, in consideration of the premises and mutual agreements set
forth herein and in the Rights Agreement, the parties hereby agree as follows:

     Section 1. Definitions. Capitalized terms used and not otherwise defined
herein shall have the meaning assigned to such terms in the Rights Agreement.

     Section 2. Amendment to Rights Agreement. The definition of "Business Day"
in Section 1 of the Rights Agreement is hereby amended to read in its entirety
as follows:

        "Business Day" shall mean any day other than a Saturday, Sunday or a day
  on which banking institutions in the State of New York are authorized or
  obligated by law or executive order to close.

     Section 3. Successor Rights Agent. The Former Rights Agent hereby resigns
as Rights Agent, the Company hereby appoints the New Rights Agent as the Rights
Agent under the Rights Agreement pursuant to Section 21 of the Rights Agreement,
and the New Rights Agent hereby accepts such appointment. Such resignation and
appointment are effective as of the date of this Amendment.

     Section 4. Miscellaneous.

     (a) The term "Agreement" as used in the Rights Agreement shall be deemed to
refer to the Rights Agreement as amended hereby.

     (b) This Amendment shall be effective as of the date first above written,
and, except as set forth herein, the Rights Agreement shall remain in full force
and effect and shall be otherwise unaffected hereby.

                                       1

<PAGE>

     (c) This Amendment may be executed in two or more counterparts, each of
which shall be deemed to be an original, but all for which together shall
constitute one and the same instrument.

     (d) This Amendment shall be deemed to be a contract made under the laws of
the State of Delaware and for all purposes shall be governed by and construed in
accordance with the laws of such State applicable to contracts to be made and
performed entirely within such State.

     (e) Except to the extent specifically amended hereby, the provisions of the
Rights Agreement shall remain unmodified, and the Rights Agreement as amended
hereby is confirmed as being in full force and effect.

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

                           CABOT OIL & GAS CORPORATION

                           By:___________________________________________

                                 Lisa A. Machesney
                           Its:  Vice President
                               ------------------------------------------

                           EQUISERVE TRUST COMPANY N.A.

                           By:___________________________________________

                           Its:__________________________________________

                           THE BANK OF NEW YORK

                           By:___________________________________________

                           Its:__________________________________________

                                       2

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