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                                                                     Exhibit 4.6

                                    AMENDMENT
                                       TO
                            STOCK PURCHASE AGREEMENT,
                             STOCKHOLDERS AGREEMENT
                                       AND
                          REGISTRATION RIGHTS AGREEMENT

            THIS AMENDMENT (this "Amendment"), dated as of May 29, 1997 among
OptiMark Technologies, Inc. (the "Company"), General Atlantic Partners 35, L.P.
("GAP 35"), GAP Coinvestment Partners, L.P. ("GAP Coinvestment"), Dow Jones &
Company, Inc. ("Dow Jones"), Alice L. Walton ("Walton"; and, together with GAP
35, GAP Coinvestment and Dow, the "Investors"), William A. Lupien, Richard W.
Jones, John T. Rickard, Alan S. Danson and The Pacific Stock Exchange
Incorporated amends (i) that certain Stock Purchase Agreement, dated August 27,
1996, as amended on October 25, 1996 and March 19, 1997 (the "Stock Purchase
Agreement"), among the Company and the Investors: (ii) that certain Stockholders
Agreement, dated as of August 27, 1996 (the "Stockholders Agreement"), among the
Company, the Investors, William A. Lupien, Richard W. Jones, John T. Rickard and
Alan S. Danson; and (iii) that certain Registration Rights Agreement, dated as
of August 27, 1996, as amended on March 19, 1997 (the "Registration Rights
Agreement"), among the Company, the Investors and The Pacific Stock Exchange
Incorporated.

            WHEREAS, pursuant to the Stock Purchase Agreement, originally dated
as of August 27, 1996, the Investors agreed to purchase, and the Company agreed
to sell, shares of Series A Convertible Participating Preferred Stock, par value
$.01 per share ("Preferred Stock"), of the Company in two sequential closings;

            WHEREAS, on August 27, 1996, the Company and the Investors
consummated the First Closing (as defined in the Stock Purchase Agreement);

            WHEREAS, on March 19, 1997, the Company and the Investors
consummated the Second Closing (as defined in the Stock Purchase Agreement) and
in connection therewith the Company issued to each Investor a warrant, dated as
of March 19, 1997, to purchase Common Stock, par value $.01 per share, of the
Company (each, an "Old Warrant;" and collectively, the "Old Warrants");

            WHEREAS, the Company would like to sell, and each of GAP 35, GAP
Coinvestment and Dow Jones would like to purchase, additional shares of
Preferred Stock pursuant to a Third Closing (as defined below); and

            WHEREAS, in order to induce GAP 35, GAP Coinvestment and Dow Jones
to consummate the Third Closing, the Company has agreed to issue to each of GAP
35, GAP Coinvestment and Dow Jones a warrant to purchase Common Stock,

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par value $.01 per share, of the Company (each, a "New Warrant;" and
collectively, the "New Warrants") in exchange for each such holder's Old
Warrant;

            NOW, THEREFORE, in consideration of the premises and for other good
and valuable consideration, the receipt and adequacy of which is hereby
acknowledged, the parties hereto agree as follows:

1. Amendment to the Stock Purchase Agreement

      (a) The definition of "Transaction Documents" in the Stock Purchase
Agreement is hereby amended by deleting it entirely and replacing it with the
following:

                  "'Transaction Documents' means collectively this Agreement,
            the Certificate of Designation, the Stockholders Agreement, the
            Registration Rights Agreement, the Employment, Trade Secret and
            Noncompetition Agreements between the Company and Messrs. Lupien and
            Rickard, the PSE-OptiMark Agreement, the PSE Revenue Sharing
            Agreement, the PSE Warrant, the Warrants issued in connection with
            the Second Closing and the New Warrants issued in connection with
            the Third Closing."

      (b) Section 2.1 of the Stock Purchase Agreement is hereby deleted in its
entirety and replaced with the following:

                  "2.1 Description of Securities. The Company has authorized the
            issuance and sale of the Preferred Shares to the Investors for a
            purchase price of $7.33 per Preferred Share. The Preferred Shares
            shall be sold in three sequential closings of 654,844 shares (the
            "First Closing"), 1,527,968 shares (the "Second Closing") and
            1,364,256 shares (the "Third Closing"), respectively, divided among
            the Investors as set forth opposite such Investor's name in Schedule
            2.1 hereto. The Company has authorized and has reserved, and
            covenants to continue to reserve, a sufficient number of shares of
            Common Stock to satisfy the rights of conversion of the holders of
            the Preferred Shares."

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      (c) The Stock Purchase Agreement is hereby amended by inserting after
Section 2.3 the following new Section:

            "2.4 Third Closing.

                  (a) Subject to Section 2.4(b), the Third Closing shall occur
            on May 29, 1997.

                  (b) The obligation of the Investors to purchase the Preferred
            Shares set forth opposite each Investor's name in Schedule 2.1 at
            the Third Closing and to pay the purchase price therefor at the
            Third Closing shall be subject to the satisfaction, or waiver by a
            Consent of the Investors, of the following conditions on the date of
            the Third Closing:

                        (i) The representations and warranties of the Company
                  contained in Section 3 hereof shall be true and correct in all
                  material respects on and as of the date of the Third Closing
                  as if made at and on such date.

                        (ii) The Company shall have performed and complied in
                  all material respects with all of its covenants and conditions
                  set forth herein that are required to be performed or complied
                  with by the Company on or before the date of the Third
                  Closing.

                        (iii) The Company shall have delivered to the Investors
                  an Officer's Certificate dated as of the Third Closing as to
                  (i) the due adoption and continuing effectiveness of the
                  resolutions of the Board, attached thereto, approving the
                  Transaction Documents and all transactions contemplated
                  thereby, (ii) the accuracy and continuing effectiveness of the
                  Certificate of Incorporation and By-laws of the Company
                  attached thereto, and (iii) the incumbency and specimen
                  signature of each officer executing the Transaction Documents
                  and the other closing documents on behalf of the Company.

                        (iv) The Investors shall have received a certificate
                  from the Company, in form and substance reasonably
                  satisfactory to the Investors, dated the date of the Third
                  Closing and signed by the Chief

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                  Executive Officer of the Company, certifying that (A) the
                  representations and warranties of the Company contained in
                  Section 3 hereof are true and correct in all material respects
                  on and as of the date of the Third Closing as if made at and
                  on such date and (B) the Company has performed and complied in
                  all material respects with all of the covenants and conditions
                  set forth herein that are required to be performed or complied
                  with by the Company on or before the date of the Third
                  Closing.

                        (v) The Investors shall have received an opinion of
                  counsel to the Company, dated as of the date of the Third
                  Closing, substantially in the form of the First Legal Opinion.

                        (vi) The Company shall issue to each Investor set forth
                  below a warrant, substantially in the form attached hereto as
                  Exhibit A (each, a "New Warrant" and collectively, the "New
                  Warrants"), exercisable into that number of outstanding shares
                  of Common Stock as set forth opposite such Investor's name
                  below:

                      Investor               Shares of Common Stock
                      --------               ----------------------
                  GAP 35                            2,763,699

                  GAP Coinvestment                    478,945

                  Dow                               2,161,764

                  (c) At the Third Closing, the Company shall issue and sell to
            each Investor, and each Investor severally and not jointly shall
            purchase from the Company, the number of Preferred Shares set forth
            opposite such Investor's name in Schedule 2.1. At the Third Closing,
            the following shall occur:

                        (i) The Company shall execute and deliver to the
                  Investors or their designated nominees certificates evidencing
                  the Preferred Shares so purchased.

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                        (ii) The Investors shall deliver the purchase price for
                  such Preferred Shares to the Company by wire transfer.

                        (iii) Each of GAP 35, GAP Coinvestment and Dow Jones
                  shall surrender the Warrant previously issued to it in
                  connection with the Second Closing to the Company for
                  cancellation."

      (d) Schedule 2.1 to the Stock Purchase Agreement is hereby deleted in its
entirety and replaced with Exhibit B, attached hereto.

2. Amendment to the Stockholders Agreement

      (a) The Stockholders Agreement is hereby amended by inserting the
following definition:

            "'Dow Jones Director' has the meaning set forth in Section 6.3(c) of
            this Agreement."

      (b) Section 2.2 of the Stockholders Agreement is hereby amended by
inserting, after the last sentence thereof, the following:

            "If any Permitted Transferee of Dow Jones to whom or which Shares
            have been transferred in accordance with this Section 2.2 ceases to
            be a Permitted Transferee of Dow Jones, then, prior to such event,
            the Dow Jones Stockholders (other than such Permitted Transferee)
            may repurchase such Shares or, if such Dow Jones Stockholders do not
            wish to repurchase such Shares, then such Permitted Transferee shall
            offer the Shares held by such Permitted Transferee to the Company,
            the General Atlantic Stockholders and the Walton Stockholders in
            accordance with Section 3.1.

            Notwithstanding anything contained in this Agreement to the
            contrary, if there is a Change of Control in Dow Jones and the
            Person who effects such a Change of Control (as defined below) is or
            thereafter becomes an OptiMark Competitor (as defined below), then
            (i) as soon as practicable after a Change of Control (or, if later,
            the date on which such Person becomes an OptiMark

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            Competitor), all of the Dow Jones Stockholders shall offer their
            Shares and Common Stock Equivalents to the Company, the OptiMark
            Stockholders, the General Atlantic Stockholders and the Walton
            Stockholders in accordance with Section 3.1 at an Offer Price that
            is mutually agreed upon by Dow Jones and the Company and (ii) the
            Dow Jones Stockholders shall cause the Dow Jones Directors to
            promptly resign from the Board of Directors and the Dow Jones
            Stockholders shall no longer be entitled to designate a director
            pursuant to Section 6.3. If Dow Jones and the Company fail to agree
            on an Offer Price within 5 Business Days after the occurrence of a
            Change of Control, then (i) the Offer Price with respect to the
            Shares shall be the greater of (x) the Fair Value per Share as
            determined in accordance with Section 3.2.2 or (y) the Exercise
            Price (as defined in the New Warrants) in effect at the time of the
            Change of Control or, if the New Warrants have expired or been fully
            exercised, the last exercise price in effect under the New Warrants
            and (ii) the Offer Price with respect to the New Warrants shall
            equal the difference, if any, between the Offer Price with respect
            to the Shares and the exercise price in effect under the New
            Warrants. If there is a Change of Control in Dow Jones and the
            Person who effects such a Change of Control is not an OptiMark
            Competitor, then the Dow Jones Stockholders shall have no obligation
            then to offer or transfer any portion of their Shares or Common
            Stock Equivalents to the Company, any Stockholder or any other
            Person, but the Dow Jones Stockholders shall cause the Dow Jones
            Directors to promptly resign from the Board of Directors and the Dow
            Jones Stockholders shall no longer be entitled to designate a
            director pursuant to Section 6.3.

            A "Change of Control" in Dow Jones shall have occurred if any one
            Person or group within the meaning of Section 13(d)(3) of the
            Exchange Act (other than the "parent" of Dow Jones described in
            footnote (6) on page 6 of its 1997 proxy statement or any Person who
            is an Affiliate of or of familial relationship to any Person
            included within such "parent") has the power to elect, directly or
            indirectly, as of any date, a majority of the directors serving on
            the board of directors of Dow Jones.

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            "OptiMark Competitor" shall mean: (i) Microsoft Corp., Reuters
            Limited, Cantor Fitzgerald LP, Investment Technology Group, Inc.,
            AZX Inc., State Street Boston Corp., Bloomberg LP and Bridge
            Information Systems Inc. or (ii) any Person who operates an
            electronic matching service for the trading of securities."

      (c) Section 4.1 of the Stockholders Agreement is hereby amended by
inserting, after clause (e), the following:

            "(f) capital stock of the Company issued pursuant to exercise of the
            Warrants and the New Warrants..."

      (d) Section 6.3 of the Stockholders Agreement is hereby deleted in its
entirety and replaced with the following:

                  "6.3 Election of Directors: Number and Composition. Each
            Stockholder shall vote its Snares and each Voting Committee Member
            shall cause the Voting Committee to vote its Shares at any
            Stockholders Meeting, or act by Written Consent with respect to such
            Shares, and take all other actions necessary to ensure that the
            number of directors constituting the entire Board of Directors shall
            be nine. Each Stockholder shall vote its Shares and each Voting
            Committee Member shall cause the Voting Committee to vote its Shares
            at any Stockholders Meeting called for the purpose of filling the
            positions on the Board of Directors, or in any Written Consent
            executed for such purpose, and to take all other actions necessary
            to ensure the ejection to the Board of Directors of the following
            individuals under the following circumstances:

                  (a) two individuals designated by the General Atlantic
            Stockholders (each a "General Atlantic Director"), for so long as
            the General Atlantic Stockholders own shares of Common Stock or
            Common Stock Equivalents convertible into or exchangeable for shares
            of voting capital stock of the Company representing (after giving
            effect to any adjustments) greater than or equal to 5% of the total
            number of shares of Common Stock outstanding on an as converted
            basis;

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                  (b) one General Atlantic Director; for so long as the General
            Atlantic Stockholders own shares of Common Stock or Common Stock
            Equivalents convertible into or exchangeable for shares of voting
            capital stock of the Company representing (after giving effect to
            any adjustments) less than 5% but greater than or equal to 2% of the
            total number of shares of Common Stock outstanding on an as
            converted basis;

                  (c) two individuals designated by the Dow Jones Stockholders
            (each a "Dow Jones Director"); for so long as the Dow Jones
            Stockholders own shares of Common Stock or Common Stock Equivalents
            convertible into or exchangeable for shares of voting capital stock
            of the Company representing (after giving effect to any adjustments)
            greater than or equal to 5% of the total number of shares of Common
            Stock outstanding on an as convened basis.

                  (d) one Dow Jones Director; for so long as the Dow Jones
            Stockholders own shares of Common Stock or Common Stock Equivalents
            convertible into or exchangeable for shares of voting capital stock
            of the Company representing (after giving effect to any adjustments)
            less than 5% but greater than or equal to 2% of the total number of
            shares of Common Stock outstanding on an as converted basis.

            Notwithstanding anything to the contrary contained in this
            Agreement. if at any time the General Atlantic Stockholders or the
            Dow Jones Stockholders own shares of Common Stock or Common Stock
            Equivalents convertible into or exchangeable for shares of voting
            capital stock of the Company representing (after giving effect to
            any adjustments) less than 2% of the total number of shares of
            Common Stock outstanding on an as converted basis, then the General
            Atlantic Stockholders or the Dow Jones Stockholders, as the case may
            be, shall no longer be entitled to designate a director pursuant to
            this Section 6.3.

                  All other directors of the Company shall be elected to the
            Board of Directors in accordance with the By-laws of the Company."

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      (e) Section 6.4 of the Stockholders Agreement is hereby amended by
inserting after Section 6.4.2 the following:

                  "6.4.3 Removal of Dow Jones Directors. If at any time the Dow
            Jones Stockholders notify the other Stockholders of their wish to
            remove at any time and for any reason (or no reason) any Dow Jones
            Director, then each Stockholder shall vote all of its Shares and
            each Voting Committee Member shall cause the Voting Committee to
            vote all of its Shares so as to remove such Dow Jones Director.

                  6.4.4 Replacement of Directors.

                  (a) If at any time, a vacancy is created on the Board of
            Directors by reason of the death, removal or resignation of a Dow
            Jones Director, then the Dow Jones Stockholders shall designate an
            individual who shall be elected to fill such vacancy until the next
            Stockholders Meeting.

                  (b) Upon receipt of notice of the designation of a nominee,
            each Stockholder and each Voting Committee Member shall, as soon as
            practicable after the date of such notice, take action, including
            (i) the voting of its Shares (in the case of each Stockholder) and
            (ii) causing the Voting Committee to vote its shares (in the case of
            each Voting Committee Member), to elect the director designated by
            the Dow Jones Stockholders to fill such vacancy."

      (f) Section 6.5 of the Stockholders Agreement is hereby deleted in its
entirety and replaced with the following:

                  "6.5 Reimbursement of Expenses. Notwithstanding anything to
            the contrary contained in this Agreement, the Company shall
            reimburse (i) GAP LP and GAP Coinvestment, or their designee, for
            all reasonable travel and other out-of-pocket expenses incurred by
            the General Atlantic Director(s) in connection with their duties as
            directors of the Company and (ii) Dow Jones for all reasonable
            travel and other out-of-pocket expenses incurred by the Dow Jones
            Director(s) in connection with their duties as directors of the
            Company."

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      (g) Section 6.6 of the Stockholders Agreement is hereby amended by
deleting the first sentence thereof in its entirety and replacing it with the
following:

            "Notwithstanding anything to the contrary contained in this
            Agreement, for so long as there is at least one General Atlantic
            Director elected pursuant to Section 6.3 on the Board of Directors,
            the Board of Directors shall not take, approve or otherwise ratify
            any of the following actions except with the consent of at least a
            majority of the directors constituting the entire Board of
            Directors; provided, however, such majority includes at least one
            General Atlantic Director or one Dow Jones Director:"

3. Amendment to the Registration Rights Agreement.

      (a) The definition of "Registrable Securities" in the Registration Rights
Agreement is hereby amended by deleting part (d) of such definition in its
entirety and replacing it with the following:

                  "(d) to the extent exercisable at the time such amount of
            Registrable Securities is to be determined, any and all shares of
            Common Stock issuable to (i) PSE upon exercise of the PSE Warrant
            and (ii) each Investor as defined in the Stock Purchase Agreement
            upon exercise of their respective Warrants and New Warrants (as
            defined in the Stock Purchase Agreement)."

      (b) Section 3 of the Registration Rights Agreement is hereby amended by
deleting the first sentence thereof in its entirety and replacing it with the
following:

            "At any time after twelve months following the IPO Effectiveness
            Date, the General Atlantic Stockholders or the Dow Jones
            Stockholders may make a written request to the Company to register
            (such General Atlantic Stockholders or Dow Jones Stockholders making
            such request being referred to hereinafter as the "Initiating
            Holders"), under the Securities Act and under the securities or
            "blue sky" laws of any jurisdiction reasonably designated by such
            holder or holders, the number of Registrable Securities, the offer
            and sale of which shall result in net proceeds (after expenses and

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            underwriting commissions and discounts) to such Initiating Holders
            of at least $5,000,000 (a "Demand Registration")."

      (c) Section 3 of the Registration Rights Agreement is hereby amended by
deleting the third sentence thereof in its entirety and replacing it with the
following:

            "The Company shall not be required to effect more than two (2)
            Demand Registration at the request of the General Atlantic
            Stockholders and one (1) Demand Registration at the request of the
            Dow Jones Stockholders pursuant to this Section 3."

4. Miscellaneous

      (a) Governing Law. This Amendment shall be governed by and construed in
accordance with the laws of the State of New York applicable to agreements made
and to be performed entirely within such State.

      (b) Assignment. This Amendment shall be binding upon the successors and
permitted assigns of the parties.

      (c) Counterparts. This Amendment may be executed by the parties hereto in
separate counterparts, each of which when so executed and delivered shall be an
original but all such counterparts together shall constitute one and the same
instrument. Each counterpart may consist of a number of copies hereof each
signed by less than all, but together signed by all of the parties hereto.

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                                                                              12


            IN WITNESS WHEREOF, the parties have executed this Amendment as of
the date first above written.


                                         OptiMark Technologies Inc.

                                         By: /s/ Alan S. Danson
                                             -----------------------------------
                                             Name: Alan S. Danson
                                             Title: Senior VP


                                         General Atlantic Partners 35, L.P.

                                         By: General Atlantic Partners, LLC its
                                             General Partner


                                             By: /s/ Steven A. Denning
                                                 -------------------------------
                                                 A Managing Member


                                         GAP Coinvestment Partners, L.P.

                                         By: /s/ Steven A. Denning
                                             -----------------------------------
                                             General Partner


                                         Dow Jones & Company, Inc.

                                         By: /s/ Kenneth L. Burenga
                                             -----------------------------------
                                             Name: Kenneth L. Burenga
                                             Title: President and Chief
                                                    Operating Officer

                                           /s/ Alice L. Walton
                                         ---------------------------------------
                                         Alice L. Walton

                                           /s/ William A. Lupien
                                         ---------------------------------------
                                         William A. Lupien, in his capacity as a
                                         Voting Committee Member for purposes of
                                         Sections 6 and 21 of the Stockholders
                                         Agreement and in his individual
                                         capacity as a Major Stockholder (as
                                         defined therein)

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                                                                              13


                                         /s/ Richard W. Jones
                                         ---------------------------------------
                                         Richard W. Jones


                                         /s/ John T. Rickard
                                         ---------------------------------------
                                         John T. Rickard, in his capacity as a
                                         Voting Committee Member for purposes of
                                         Sections 6 and 21 of the Stockholders
                                         Agreement and in his individual
                                         capacity as a Major Stockholder (as
                                         defined therein)

                                         /s/ Alan S. Danson
                                         ---------------------------------------
                                         Alan S. Danson, in his capacity as a
                                         Voting Committee Member for purposes of
                                         Sections 6 and 21 of the Stockholders
                                         Agreement


                                         The Pacific Stock Exchange Incorporated


                                         By: /s/ John C. Katovich
                                             -----------------------------------
                                             Name:  John C. Katovich
                                             Title: Sr. Vice President, General
                                                    Counsel and Director of
                                                    Legal Affairs