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                                                        Exhibit 4.12




                          JUPITER MEDIA METRIX, INC.
                            STOCK OPTION AGREEMENT


            AGREEMENT made as of the 27th day of December, 2000, by and between
Jupiter Media Metrix, Inc., a Delaware corporation (the "COMPANY"), and IPSOS
S.A, a French corporation (the "OPTIONEE").

                             W I T N E S S E T H
                             -------------------

            WHEREAS, the Company and the Optionee (together the
"SHAREHOLDERS") are shareholders of JMXI Latin America B.V. ("JMXI LATIN
AMERICA B.V."); and

            WHEREAS, the Company desires to grant to the Optionee, and the
Optionee desires to accept, an option (the "OPTION") to acquire shares of common
stock, $.01 par value, of the Company (the "COMMON STOCK") upon the terms and
conditions set forth in this agreement.

            NOW, THEREFORE, the parties hereto agree as follows:

            1. GRANT.

            (a) Subject to the terms and conditions set forth in this Stock
Option Agreement, the Company hereby grants to the Optionee an Option to
exchange all, but not less than all shares of JMXI Latin America B.V. (the
"SHARES") for shares of Common Stock at any time during a five (5) year period
commencing at 9:00 am (New York time) on December 22, 2000 and ending at 5:00 pm
(New York time) December 21, 2005 (the "EXCHANGE PERIOD"). The number of shares
of Common Stock Optionee shall receive shall be determined by dividing the
aggregate U.S. dollar amount of Optionee's investment (determined based on the
Euro-U.S. dollar exchange rate quoted in the Wall Street Journal on the date
hereof) in JMXI Latin America B.V. by US$10.00 (the "PER SHARE OPTION PRICE").

            (b) The Option may be exercised by the Optionee if the net annual
revenues of JMXI Latin America B.V. exceed 60% of the budgeted net annual
revenues set forth in the budget approved by the board of JMXI Latin American
B.V. for the period ending December 31 of the prior year.

            2. EXERCISES; REPRESENTATIONS AND WARRANTIES.

            (a) The Option may be exercised in whole but not in part in
accordance with Section 1 hereof by delivering to the Secretary of the Company
(a) a written notice specifying the number of shares to be acquired, and (b)
delivery of certificates representing the Shares. It shall be a condition to the
issuance of the Common Stock certificates that an amount, if any, deemed
necessary by the Company to enable it to satisfy any income tax withholding
obligations with respect to the exercise shall be remitted to the Company
(unless other arrangements acceptable to the Company are made for the
satisfaction of such withholding obligations).

            (b) The Company hereby represents and warrants the following to the
Optionee:
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                  (i) The Company has the full right, power and authority to
      enter into this Agreement and to allot and set aside such number of shares
      of Common Stock as is necessary upon the exercise of the Option.

                  (ii) This Agreement has been duly authorized, executed and
      delivered and constitutes the legal, valid and binding obligations of the
      Company, enforceable in accordance with its terms, except as enforcement
      may be limited by bankruptcy, insolvency, moratorium or other laws
      affecting creditors' rights generally, or equity principles, whether in a
      proceeding in equity or law.

                  (iii) The Company has not, to its knowledge, taken any action
      which would cause it to violate the Securities Act of 1933, as amended, or
      the Securities Exchange Act of 1934, as amended.

                  (iv) The Common Stock subject to the exercise of the Option
      will be, at the time of the exercise of the Option, listed on NASDAQ.

                  (v) The execution and delivery of this Agreement by the
      Company will not result in a violation of, be in conflict with, or
      constitute a default under, with or without the passage of time or the
      giving notice: (i) any provision of the certificate of incorporation or
      by-laws of the Company, (ii) any material contract or other arrangement to
      which the Company is bound or (iii) any statute, rule or governmental
      regulation applicable to the Company. The execution and delivery of this
      Agreement by the Company will not impair the Company's ability to issue
      Common Stock.

                  (vi)  The Company has obtained all necessary consents or
      approvals necessary for execution, delivery and performance of this
      Agreement.

            3. RESERVATION OF SHARES; LISTING. The Company agrees that, prior to
the expiration of this Option, the Company will at all times have authorized and
in reserve, and will keep available, solely for issuance or delivery upon the
exercise of this Option, the shares of the Common Stock and other securities and
properties as from time to time shall be receivable upon the exercise of this
Option, free and clear of all restrictions on sale or transfer and free and
clear of all preemptive rights and rights of first refusal and keep the shares
of the Common Stock receivable upon the exercise of this Option authorized for
listing on NASDAQ upon notice of issuance.

            4. PROTECTION AGAINST DILUTION.

            (a) In case the Company shall hereafter (i) pay a dividend or make a
distribution on its capital stock in shares of Common Stock, (ii) subdivide its
outstanding shares of Common Stock into a greater number of shares, (iii)
combine its outstanding shares of Common Stock into a smaller number of shares
or (iv) issue by reclassification of its Common Stock any shares of capital
stock of the Company, the Per Share Option Price shall be adjusted so that the
Optionee upon the exercise hereof shall be entitled to receive the number of
shares of Common Stock or other capital stock of the Company which it would have
owned immediately following such action had such Option been exercised
immediately prior thereto. An adjustment made pursuant to this Subsection 4(a)
shall become effective immediately after the record date in


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the case of a dividend or distribution and shall become effective immediately
after the effective date in the case of a subdivision, combination or
reclassification.

            (b) If, at any time or from time to time after the date of this
Option, the Company shall issue or distribute to the holders of shares of Common
Stock evidences of its indebtedness, any other securities of the Company or any
cash, property or other assets (excluding a subdivision, combination or
reclassification, or dividend, and also excluding cash dividends or cash
distributions paid out of net profits legally available therefor if the full
amount thereof, together with the value of other dividends and distributions
made substantially concurrently therewith or pursuant to a plan which includes
payment thereof, is equivalent to not more than 5% of the Company's net worth)
(any such nonexcluded event being herein called a "SPECIAL DIVIDEND"), the Per
Share Option Price shall be adjusted by multiplying the Per Share Option Price
then in effect by a fraction, the numerator of which shall be the then current
market price of the Common Stock (defined as the average for the five
consecutive business days immediately prior to the record date of the daily
closing price of the Common Stock as reported by the national securities
exchange upon which the Common Stock is then listed or if not listed on any such
exchange, the average of the closing prices as reported by NASDAQ) less the fair
market value (as determined by the Company's Board of Directors) of the
evidences of indebtedness, cash, securities or property, or other assets issued
or distributed in such Special Dividend applicable to one share of Common Stock
and the denominator of which shall be such then current market price per share
of Common Stock. An adjustment made pursuant to this Subsection 4(b) shall
become effective immediately after the record date of any such Special Dividend.

            (c) In case of any capital reorganization or reclassification, or
any consolidation or merger to which the Company is a party other than a merger
or consolidation in which the Company is the continuing corporation, or in case
of any sale or conveyance to another entity of the property of the Company as an
entirety or substantially as an entirety, or in the case of any statutory
exchange of securities with another corporation (including any exchange effected
in connection with a merger of a third corporation into the Company), the
Optionee shall have the right thereafter to receive on the exercise of this
Option the kind and amount of securities, cash or other property which the
holder would have owned or have been entitled to receive immediately after such
reorganization, reclassification, consolidation, merger, statutory exchange,
sale or conveyance had this Option been exercised immediately prior to the
effective date of such reorganization, reclassification, consolidation, merger,
statutory exchange, sale or conveyance and in any such case, if necessary,
appropriate adjustment shall be made in the application of the provisions set
forth in this Section 4 with respect to the rights and interests thereafter of
the Optionee to the end that the provisions set forth in this Section 4 shall
thereafter correspondingly be made applicable, as nearly as may reasonably be,
in relation to any shares of stock or other securities or property thereafter
deliverable on the exercise of this Option. The above provisions of this
Subsection 4(c) shall similarly apply to successive reorganizations,
reclassifications, consolidations, mergers, statutory exchanges, sales or
conveyances. The issuer of any shares of stock or other securities or property
thereafter deliverable on the exercise of this Option shall be responsible for
all of the agreements and obligations of the Company hereunder. Notice of any
such reorganization, reclassification, consolidation, merger, statutory
exchange, sale or conveyance and of said provisions so proposed to be made,
shall be mailed to the holders of the Options not less than 30 days prior to
such event. A sale of all or substantially all of the


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assets of the Company for a consideration consisting primarily of securities
shall be deemed a consolidation or merger for the foregoing purposes.

            (d) No adjustment in the Per Share Option Price shall be required
unless such adjustment would require an increase or decrease of at least $0.05
per share of Common Stock; provided, however, that any adjustments which by
reason of this Subsection 4(d) are not required to be made shall be carried
forward and taken into account in any subsequent adjustment. All calculations
under this Section 4 shall be made to the nearest cent or to the nearest 1/l00th
of a share, as the case may be. Anything in this Section 4 to the contrary
notwithstanding, the Company shall be entitled to make such reductions in the
Per Share Option Price, in addition to those required by this Section 4, as it
in its discretion shall deem to be advisable in order that any stock dividend,
subdivision of shares or distribution of rights to purchase stock or securities
convertible or exchangeable for stock hereafter made by the Company to its
stockholders shall not be taxable.

            (e) If the Board of Directors of the Company shall (i) declare any
dividend or other distribution with respect to the Common Stock, other than a
cash dividend subject to the first parenthetical in Subsection 4(b), (ii) offer
to the holders of shares of Common Stock any additional shares of Common Stock,
any securities convertible into or exercisable for shares of Common Stock or any
rights to subscribe thereto, or (iii) propose a dissolution, liquidation or
winding up of the Company, the Company shall mail notice thereof to the Optionee
not less than 15 days prior to the record date fixed for determining
stockholders entitled to participate in such dividend, distribution, offer or
subscription right or to vote on such dissolution, liquidation or winding up.

            (f) If, as a result of an adjustment made pursuant to this Section
4, the holder of any Option thereafter surrendered for exercise shall become
entitled to receive shares of two or more classes of capital stock or shares of
Common Stock and other capital stock of the Company, the Board of Directors
(whose determination shall be conclusive and shall be described in a written
notice to the holder of any Option promptly after such adjustment) shall
determine the allocation of the adjusted Per Share Option Price between or among
shares or such classes of capital stock or shares of Common Stock and other
capital stock.

            (g) Upon each adjustment of the Per Share Option Price pursuant to
the provisions of this Section 4, the number of shares of Common Stock issuable
upon the exercise at the adjusted Per Share Option Price of the Option shall be
adjusted to the nearest full amount by multiplying a number equal to the Per
Share Option Price in effect immediately prior to such adjustment by the number
of shares of Common Stock issuable upon exercise of the Option immediately prior
to such adjustment and dividing the product so obtained by the adjusted Per
Share Option Price.

            5. RIGHTS AS STOCKHOLDER. Upon the exercise of the Option in
accordance with the terms hereof, the Company shall cause the number of shares
of Common Stock issuable to be issued to the Optionee as fully paid and
non-assessable shares of Common Stock and shall cause the share certificates
representing such shares to be delivered to the Optionee as soon as possible
thereafter. No shares of Common Stock shall be sold or delivered hereunder until
full payment for such shares has been made. The Optionee shall have no rights as
a stockholder with


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respect to any share covered by the Option until stock certificate for such
shares is issued to the Optionee. Expect as otherwise provided herein, no
adjustment shall be made for dividends or distributions of other rights for
which the record date is prior to the date such stock certificate is issued.

            6. LIMITED TRANSFERABILITY. This Option may not be sold,
transferred, assigned or hypothecated by the Optionee except in compliance with
the provisions of the Securities Act of 1933, as amended. The Company may treat
the registered holder as he or it appears on the Company's books at any time as
the holder for all purposes. The Company shall permit any Optionee or his duly
authorized attorney, upon written request during ordinary business hours, to
inspect and copy or make extracts from its books showing the registered holders
of options. All options issued upon the transfer or assignment of this Option
will be dated the same date as this Option, and all rights of the holder thereof
shall be identical to those of the Optionee.

            7. ADMINISTRATION. The Board of Directors of the Company will have
full power and authority to interpret and apply the provisions of this agreement
on behalf of the Company and act on behalf of the Company in connection with
this agreement, and the decision of the Board of Directors of the Company as to
any matter arising under this agreement shall be binding and conclusive as to
the Company.

            8. MISCELLANEOUS.

            (a) This agreement shall be binding upon and shall inure to the
benefit of the parties hereto and their respective successors and permitted
assigns.

            (b) This agreement shall be governed by and construed in accordance
with the laws of the State of Delaware. Except as specified in the Shareholders'
Agreement by and between the parties hereto dated as of the date hereof, this
agreement constitutes the entire agreement between the parties with respect to
the subject matter hereof and may not be modified except by written instrument
executed by the parties.

            (c) The parties hereto agree that any dispute, disagreement or
controversy between any party relating to this Agreement that cannot be resolved
by the parties shall promptly be submitted to arbitration to be resolved by
final and binding arbitration in accordance with the provisions of the American
Arbitration Association. The place of arbitration shall be New York, New York.
The arbitration tribunal shall be composed of three arbitrators who have
sufficient experience in the matters at hand, one of whom shall be appointed by
the Company, one of whom shall be appointed by Optionee and one of whom shall be
appointed by such two arbitrators. The arbitrators will be directed to and shall
resolve such dispute, disagreement or controversy on the basis of the
information provided to them as soon as practicable. The arbitration award shall
be given in writing and shall be final, binding on the parties, not subject to
any appeal, and shall deal with questions of costs of arbitration and all
matters related thereto.


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            IN WITNESS WHEREOF, this agreement has been executed as of the date
first above written.

                                    JUPITER MEDIA METRIX, INC.


                                    By:  /s/ Tod Johnson
                                       -----------------------------------


                                    IPSOS S.A.


                                    By: /s/ Didier Truchot
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