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                                                                   Exhibit 10.16

                                                                  EXECUTION COPY

                      FOURTH LEASE MODIFICATION AGREEMENT

                          Kenvic Associates, Landlord

                                      with

                          Instinet Corporation, Tenant

                               February 14, 1996

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                      FOURTH LEASE MODIFICATION AGREEMENT

      THIS FOURTH LEASE MODIFICATION AGREEMENT (the "Agreement"), dated as of
February 14, 1996, between KENVIC ASSOCIATES, a partnership having an office at
875 Third Avenue, New York, New York 10022 ("Landlord") and INSTINET
CORPORATION, a Delaware corporation having an office at 875 Third Avenue, New
York, New York 10022 ("Tenant").

                              W I T N E S S E T H:

      WHEREAS, Landlord and Tenant are parties to that certain lease dated as of
November 19, 1992, as modified by a Lease Modification Agreement dated as of
July 9, 1993 (the "First Lease Modification Agreement") between Landlord and
Tenant, relating to the entire eighteenth (18th), twenty-eighth (28th) and
twenty-ninth (29th) floors in the Building; a Second Lease Modification
Agreement dated June 7, 1994 (the "Second lease Modification Agreement") between
Landlord and Tenant relating to a portion of the twenty-seventh (27th) floor of
the Building and a Third Lease Modification Agreement dated as of October 21,
1994 (the "Third Lease Modification Agreement") between Landlord and Tenant,
relating to a portion of the third (3rd) floor in the Building (said lease, as
so modified by the First Lease Modification Agreement, the Second Lease
Modification

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Agreement and the Third Lease Modification Agreement, is hereinafter referred to
as, the "Lease");

      WHEREAS, pursuant to the Second Lease Modification Agreement, Tenant has
exercised its option to Lease the entire nineteenth (19th) floor of the Building
(the "Additional 19th Floor Premises").

      WHEREAS, Landlord and Tenant desire to modify the Lease as hereinafter set
forth;

      NOW, THEREFORE, in consideration of the premises, and for good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, and of the mutual agreements herein, the Lease is amended as
follows:

      1. All the terms of this Agreement, the initial letters of which are
capitalized and not otherwise defined, shall have the meanings set forth in the
Lease.

      2. Effective upon the delivery of Vacant Possession of the Additional 19th
Floor Premises (the "19th Floor Delivery Date"), Section 1.02 of the Lease is
modified by adding to the Premises the Additional 19th Floor Premises and the
term "Premises" shall thereafter include the Additional 19th Floor Premises. The
rentable square foot area of the Additional 19th Floor Premises is hereby deemed
to be 26,000 rentable square feet.


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      3. Sections 7C(a) of the First Lease Modification Agreement is hereby
deleted in its entirety and replaced with the following:

      "(a) Tenant acknowledges that the existing tenant of the Additional 19th
      Floor Premises has consented to the entry of a judgment of possession of
      the Additional 19th Floor Premises and to the issuance of a warrant of
      eviction granting legal and physical possession of the Additional 19th
      Floor Premises to Landlord but with a stay of the execution of such
      warrant of eviction until no later than November 30, 1996. Commencing no
      later than December 2, 1996, Landlord will use all reasonable efforts to
      cause the warrant of eviction to be executed. No later than one (1)
      business day after the date legal and physical possession is delivered to
      Landlord upon the execution of such warrant of eviction, Landlord shall
      deliver a written notice to Tenant advising Tenant of such delivery.
      Tenant shall, within one (1) business day after such written notice is
      delivered, inspect the Additional 19th Floor Premises to determine if said
      Additional 19th Floor Premises are, in fact, free of all property of the
      former occupants thereof. Unless within said same business day on which
      the Tenant has such right to inspect, Tenant delivers a written notice to
      Landlord identifying property of the former occupant which remains on the
      Additional 19th Floor Premises, Landlord and Tenant agree that Vacant
      Possession of the Additional 19th Floor Premises shall be deemed to have
      been delivered by Landlord to Tenant one (1) business day after such
      written notice was delivered by Landlord to Tenant."

      4. Notwithstanding the provisions of Section 7(C) (a) of the First Lease
Modification Agreement, as modified by this Agreement, Landlord shall, at any
time after the date hereof that Vacant Possession of the Additional 19th Floor
Premises is delivered to Landlord (and


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upon three (3) business days written notice to Tenant), deliver Vacant
Possession of the Additional 19th Floor Premises to Tenant, which delivery shall
be deemed to occur upon the expiration of said third (3rd) business day.

      5. Section 7E of the First Lease Modification Agreement is hereby modified
by (a) deleting the words "within five (5) months following the expiration of
the Kasowitz Lease" in the 23rd and 24th lines of said Section and replacing
them with the words "by February 15, 1997." and (b) deleting the words "9 months
after the expiration of the Kasowitz Lease" in line 27 of said Section and
replacing such words with the words "between February 16, 1997 and March 1,
1997".

      6. Section 7B(i) of the Second Lease Modification Agreement is hereby
modified by deleting said section and replacing it with the following:

            (i) By deleting subparagraph (b) from paragraph C of Section 7
      thereof and replacing it with the following:

            "(b) From and after the date of delivery or deemed delivery to
            Tenant of Vacant Possession of the Additional 19th Floor Premises,
            Fixed Rent, as defined in Article 3 of the Lease, shall be increased
            (i) if such Vacant Possession is delivered or deemed delivered prior
            to July 1, 1996, by $668,750 per annum for the period beginning on
            the date such Vacant Possession is delivered or deemed delivered and
            ending June 30,


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            1996 and by an additional $43,650 per annum for the period from July
            1, 1996 through July 31, 1998 and (ii) if Vacant Possession is not
            delivered or deemed delivered prior to July 1, 1996 by $712,400 per
            annum for the period from the date on which such Vacant Possession
            is delivered or is deemed delivered through July 31, 1998. In
            addition, Fixed Rent shall be increased by an additional $104,000
            per annum from and after August 1, 1998."


      7. Effective as of the 19th Floor Delivery Date, Articles 6 (TAX PAYMENTS)
and 7 (ESCALATION) of the Lease are modified (and Paragraph 4 of the Third Lease
Modification Agreement and Subparagraph (c) of Paragraph (C) of Section 7 of the
First Lease Modification Agreement are superseded) so that the Tenant's Share is
increased to 19.96%; provided however (A) for purposes of Article 6, (a) the
Base Tax for 16.33/19.96 of the Tenant's Share shall be Real Estate Taxes for
the 1993/1994 Tax year, and (b) the Base Tax for 3.63/19.96 of the Tenant's
Share shall be Real Estate Taxes for the 1994/1995 Tax Year and (B) for purposes
of Article 7, (a) the Expense Base for 16.33/19.96 of the Tenant's Share shall
be the average of the Expenses for the 1993 Calendar Year and the 1994 Calendar
Year, (b) the Expense Base for 2.12/19.96 of the Tenant's Share shall be the
1994 Calendar Year and (c) the Expense Base for 1.51/19.96 of the Tenant's Share
shall be the 1995 Calendar Year. Tenant acknowledges that it is not entitled to
any



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further reduction of Tenant's Share pursuant to the "provided, however" clause
at line 2 of Section 6.01(a) (v) of the Lease.

      8. Effective as of the 19th Floor Delivery Date, the Lease is further
modified as follows:

            A. By adding to Section 10.10 of the lease "or the Additional 19th
Floor Premises" after the words "Additional 3rd Floor Premises" on line 4 of
said section.

            B. By deleting from the last sentence of Section 22.09 of the Lease
the (i) words "execution and delivery of this Agreement" and replacing such
words with the words "19th Floor Delivery Date" and (ii) the number "110,875"
and replacing it with the number "136,875".

            C. by inserting in Section 24.02 of the Lease after the words "the
Additional 3rd Floor Premises" on line 2 thereof the words "and the Additional
19th Floor Premises."


            D. By modifying Section 43.01 of the Lease by inserting on line 26
thereof, after the word "including" the words "the Additional 19th Floor
Premises."


      9. Tenant represents that in the negotiation of this Agreement it dealt
with no broker other than Koll Management Services, Inc. (the "Broker") and no
other broker participated in bringing about this Agreement. Tenant hereby
indemnifies and agrees to defend and hold Landlord


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harmless against any claim or liability arising out of any inaccuracy or alleged
inaccuracy of the above representation. The parties hereto acknowledge that the
Broker will be paid a commission in accordance with a separate agreement between
Landlord and Broker. Landlord represents that to the best of Landlord's
knowledge, it has not dealt with any broker other than the Broker in connection
with this Agreement.

      10. Except as modified by this Agreement, the Lease shall remain in full
force and effect in accordance with its terms and (except for the
representations set forth therein) is hereby ratified and confirmed.

      11. This Agreement shall be binding on and shall inure to the benefit of
the parties hereto and their respective successors and permitted assigns.

      IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
as of the date first above written

                                    LANDLORD:

WITNESS:                            KENVIC ASSOCIATES

/s/ John C. Lisher                  By: /s/ Lucille Gladstone
----------------------------            -------------------------------
                                        Name: Lucille Gladstone
                                        Title: Partner


                                    TENANT:

WITNESS:                            INSTINET CORPORATION

                                    By: /s/ Daniel M. Rosenthal
----------------------------            -------------------------------
                                        Name: Daniel Rosenthal
                                        Title: Senior Vice President


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                          LANDLORD'S ACKNOWLEDGEMENT

STATE OF NEW YORK  )
                   : ss.:
COUNTY OF NEW YORK )

            On this ___ day of February, 1996, before me personally came Lucille
Gladstone, to me known, who, being by me duly sworn, did depose and say that she
is a partner in the firm of KENVIC ASSOCIATES, a New York partnership, and that
she executed the foregoing instrument as and on behalf of said partnership.


                                                     ---------------------------
                                                            Notary Public

                       CORPORATE TENANT'S ACKNOWLEDGEMENT

STATE OF NEW YORK  )
                   : ss.:
COUNTY OF NEW YORK )

            On this 14th day of February, 1996, before me personally came Daniel
Rosenthal, to me known, who, being by me duly sworn, did depose and say that the
resides at
                                                                              ;
that he is the Senior Vice President of Instinet Corporation, the corporation
described in and which executed the foregoing Lease, as Tenant, and that he
signed his name thereto by order of that corporation's board of directors.


                                                     ---------------------------
                                                            Notary Public


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