Document:

<PAGE>   1
                                                                     Exhibit 4.4

                               MEDIA METRIX, INC.
                             STOCK OPTION AGREEMENT

         AGREEMENT made as of the 6th day of March, 2000, by and between Media
Metrix, Inc., a Delaware corporation (the "Company"), and Osprey Research B.V.,
a Netherlands limited liability company and a wholly-owned subsidiary of SIFO
Group AB (the "Optionee").

                               W I T N E S S E T H

         WHEREAS, the Company, the Optionee, GfK AG ("GFK") and IPSOS SA
("IPSOS" and together with the Company, the Optionee and GfK, the
"SHAREHOLDERS") are shareholders of MMXI Europe B.V. ("MMXI EUROPE"); 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 up to (euro)782,609 of shares of MMXI Europe (the "SHARES") for shares
of Common Stock at any time during a five (5) year period commencing on May 7,
2000 and ending at 5:00 p.m. (New York time) May 7, 2005 (the "EXCHANGE
PERIOD"). The maximum number of Shares which may be exchanged shall be
calculated on the basis of the Optionee's cash contribution with respect to such
Shares, it being understood that the amount of contributions exchangeable into
Common Stock shall not exceed an aggregate of (euro)782,609. The number of
shares of Common Stock to be issued upon exercise of the Option shall be
determined by dividing (i) the amount of the cash capital contributions made to
MMXI Europe with respect to the Shares to be exchanged (expressed in U.S.
Dollars at the rate at which Euros are converted into U.S. Dollars as posted in
The Wall Street Journal the business day prior to the exercise of the Option) by
(ii) $39.4375 (the "PER SHARE OPTION PRICE").

              (b) If the Shareholders elect to finance MMXI Europe by making
loans rather than additional capital contributions, the Optionee may exchange
the notes evidencing any such loan (the "NOTES") for shares of Common Stock at
any time during the Exchange Period; provided, however, that the aggregate value
of Shares and Notes exchanged shall not exceed (euro)782,609. The
<PAGE>   2
number of shares of Common Stock to be issued upon exercise of the Option shall
be determined by dividing (i) the principal amount of the Notes (expressed in
U.S. Dollars at the rate at which Euros are converted into U.S. Dollars as
posted in The Wall Street Journal the business day prior to the exercise of the
Option) by (ii) the Per Share Option Price.

              (c) If, upon the third anniversary of this Agreement, the
aggregate capital contributions to MMXI Europe by the Company, the Optionee, GfK
and IPSOS are less than (euro)9,782,609, then the Optionee shall have the option
to purchase for cash, at the Per Share Option Price, an amount of Common Stock
equal to 8% of the difference between (euro)9,782,609 and such aggregate capital
contributions, such difference expressed in U.S. dollars at the rate which Euros
are converted into dollars as posted in The Wall Street Journal on the business
day prior to the exercise of the Option.

              (d) The Option may be exercised only if, on December 31 of the
immediately preceding year, the revenues of MMXI Europe exceed the targets
agreed to among the Company, the Optionee, GfK and IPSOS and the Company's has
received the notice to be delivered pursuant to Section 2 below.

              (e) Upon a Change in Control (as such term is defined in the
Shareholders' Agreement, dated as of the September 1, 1999 as amended, among
MMXI Europe, the Optionee, GfK, IPSOS and the Company) of the Company, the
Optionee shall thereafter have the right to exercise the Option regardless of
whether the date of exercise precedes May 7, 2000 or the level of the revenues
of MMXI Europe.

              (f) All calculations in this Section 1 shall be made to the
nearest cent or the nearest integer of a share of Common Stock.

         2. EXERCISE. The Option may be exercised in whole or 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 the Shares and/or the Notes, together with the amount, if any,
deemed necessary by the Company to enable it to satisfy any income tax
withholding obligations with respect to the exercise (unless other arrangements
acceptable to the Company are made for the satisfaction of such withholding
obligations).

         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

                                       -2-
<PAGE>   3
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 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 non-excluded 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.

                                       -3-
<PAGE>   4
              (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 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; provided further,
however, that adjustments shall be required and made in accordance with the
provisions of this Section 4 (other than this Subsection 4(d)) not later than
such time as may be required in order to preserve the tax-free nature of a
distribution to the Optionee or Common Stock issuable upon exercise hereof. 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.

                                       -4-
<PAGE>   5
              (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 of the Option at the adjusted Per Share Option Price 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. No shares of Common Stock shall be sold or
delivered hereunder, nor shall the Optionee become a stockholder, until the
conditions set forth in Section 2 hereof shall have been met. Except 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. Upon exercise of this
Option, at the request of the Company the Shares shall be transferred by the
Optionee to the Company by means of a notarial deed of transfer ("notariele akte
houdende levering") of the Shares (the "DEED OF TRANSFER"), to be executed
before one of the civil law notaries ("notarissen") of De Brauw Blackstone
Westbroek N.V. Payment of the Per Share Option Price shall be deemed to have
taken place simultaneously with the execution of the Deed of Transfer. The
Company may treat the registered holder of Options as it appears on the
Company's books at any time as the holder for all purposes of such Options. The
Company shall permit any Optionee or his duly authorized attorney, upon written
request during ordinary business hours, to

                                       -5-
<PAGE>   6
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. 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. All rights and obligations of the Optionee hereunder shall be assigned
to SIFO Group AB ("SIFO") if the Optionee transfers its shares in MMXI Europe to
SIFO.

              (b) This agreement shall be governed by and construed in
accordance with the laws of the State of Delaware. 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) All disputes arising out of this Option, including, without
limitation, disputes concerning the existence and validity thereof, shall be
resolved by binding arbitration in accordance

with the rules of the Netherlands Arbitration Institute (Netherlands Arbitrage
Instituut, the "NAI") and in accordance with the following:

                  (i) the arbitral tribunal shall be comprised of three
         arbitrators, one of whom shall be appointed by the Company, one of whom
         shall be appointed by the Optionee and one of whom shall be appointed
         by the first two arbitrators;

                  (ii) the place of arbitration shall be Amsterdam, The
         Netherlands;

            [the remainder of this page was intentionally left blank]

                                      -6-
<PAGE>   7
                  (iii) all proceedings shall be conducted in the English
         language;

                  (iv) the tribunal shall make its determination in accordance
         with the rules of the law;

                  (v) the proceedings may not be consolidated with any other
         arbitration proceedings pursuant to Section 1046 of the Code of the
         Civil Procedure (Wetboek van urgerlijke Rechtsvordering), unless such
         other proceedings are conducted exclusively between the parties to this
         Option; and

                  (vi) the arbitral judgment may not be published by the NAI.

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

                                          MEDIA METRIX, INC.

                                          By: /s/ Thomas A. Lynch
                                              ----------------------------------

                                          OSPREY RESEARCH B.V.

                                          By: /s/ Jan-Erik Jannsson
                                              ----------------------------------<PAGE>   1
                                                                     Exhibit 4.5

                   AMENDMENT TO REGISTRATION RIGHTS AGREEMENT

         AMENDMENT TO REGISTRATION RIGHTS AGREEMENT (this "AMENDMENT") made as
of March 6, 2000 by and among MEDIA METRIX, INC., a Delaware corporation (the
"COMPANY"), GfK AG ("GFK"), a German stock corporation, IPSOS S.A. ("IPSOS"), a
French stock corporation and Osprey Research B.V. ("OSPREY"), a Netherlands
limited liability company and a wholly-owned subsidiary of SIFO Group AB, a
Swedish corporation.

                              W I T N E S S E T H:

         WHEREAS, the Company, GfK and IPSOS have entered into a Registration
Rights Agreement, dated as of September 1, 1999, a copy of which is attached to
this Amendment (the "REGISTRATION RIGHTS AGREEMENT"), providing, among other
things, certain terms and conditions upon which the Company will register the
shares of the Company's Common Stock issuable to GfK and IPSOS, respectively,
upon exercise of certain stock options.

         WHEREAS, the Company and Osprey have entered into a Stock Option
Agreement, dated as of the date hereof (the "OSPREY STOCK OPTION")

         WHEREAS, the Company wishes to grant registration rights to Osprey with
respect to the shares of the Company's Common Stock issuable to Osprey upon
exercise of the Osprey Stock Option and GfK and IPSOS have agreed that the
registration rights granted to Osprey shall be pari passu with the rights
granted to GfK and IPSOS in to the Registration Rights Agreement.

         NOW, THEREFORE, in consideration of the premises and mutual covenants
and agreements herein contained, and for other good and valuable consideration,
the receipt and sufficiency of which is hereby acknowledged, the parties hereto
agree as follows:

         1. CONTINUATION OF REGISTRATION RIGHTS AGREEMENT

         The Registration Rights Agreement shall continue in full force and
effect as amended by this Amendment. All capitalized terms not otherwise defined
in this Amendment shall have the meanings given in the Registration Rights
Agreement.

         2. ADDITION OF OSPREY AS A HOLDER

         The Registration Rights Agreement is hereby amended to add Osprey as a
Holder for all purposes thereunder. Without limiting the generality of the
foregoing, references in the Registration Rights Agreement to "either Holder"
are hereby amended to read "any Holder" and references in the Registration
Rights Agreement to "Registrable Securities" is hereby amended to include the
Common Stock issuable to Osprey upon exercise of the Osprey Stock Option.

<PAGE>   2
         3. NOTICES.

         Schedule I to the Registration Rights Agreement is hereby amended to
add the following address for all notices and other communications delivered to
Osprey:

Mr. Robert Kessiakoff
Osprey Research B.V.
c/o SIFO Group AB
World Trade Center
Box 70408, SE-107
25 Stockholm, Sweden
Fax: +46 8 698 0933
Phone: +46 8 701 6990
email: robert.kessiakoff@sifo.se

with a copies to:

Peter Torngren                                    Hunton & Williams
Box 1703, SE-111                                  200 Park Avenue
87 Stockholm, Sweden                              New York, NY
Fax: +4670-714-31-71                              Attn: Edmund P. Murphy, Esq.
Phone: +46-8--614-30-00                           Fax: (212) 309-1100
email: peter.torngren@vinge.se

         4. GOVERNING LAW.

         This Amendment is to be governed by and interpreted under the laws of
the State of Delaware without giving effect to the principles of conflicts of
laws thereof.

         5. COUNTERPARTS.

         This Amendment may be executed in any number of counterparts, each of
which shall be an original, but all of which together shall constitute one
instrument.

                                       -2-
<PAGE>   3
IN WITNESS WHEREOF, the parties hereto have executed this Registration Rights
Agreement as of the date first above written.

                                MEDIA METRIX, INC.

                                By: /s/ Thomas A. Lynch
                                    _________________________________
                                    Name: Thomas A. Lynch
                                    Title: Chief Financial Officer

                                IPSOS S.A.

                                By: /s/ Didier Truchot
                                    _________________________________
                                    Name: Didier Truchot
                                    Title: Chairman and Chief
                                           Executive Officer

                                GFK AG

                                By: /s/ Gerhard Kirschner
                                    _________________________________
                                    Name: Gerhard Kirschner
                                    Title: Member of the Board

                                OSPREY RESEARCH B.V.

                                By: /s/ Jan-Erik Jannsson
                                    _________________________________
                                    Name: Jan-Erik Jannsson
                                    Title: Director

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00003-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00003-of-00352.parquet"}]]