<PAGE>   1
                                                                   EXHIBIT 10.23
                                    SUBLEASE

     This Sublease (this "Sublease"), dated as of April  , 2001 between REUTERS
C CORP. ("Sublessor"), having an address at 3 Times Square, New York, New York,
and INSTINET GLOBAL HOLDINGS, INC. ("Subtenant"), having an address at 875 Third
Avenue, New York, New York.

                              W I T N E S S E T H:

     WHEREAS, Sublessor entered into that certain Agreement of Lease, dated
February 18, 1998, between 3 Times Square Associates, LLC ("Overlandlord"), as
landlord, and Sublessor, as tenant, as amended by First Amendment of Lease,
dated as of June 30, 1998, Second Amendment of Lease, dated as of July 1, 1998,
Third Amendment of Lease, dated as of March 31, 2000, and Fourth Amendment of
Lease, dated as of November 28, 2000 (the foregoing lease as so amended and as
the same may hereafter from time to time be amended, modified, extended, renewed
or supplemented, the "Overlease") for premises described in the Overlease and
located in the building (the "Building") known as Three Times Square, New York,
New York; and

     WHEREAS, Subtenant desires to sublease from Sublessor floors 6 though 14
in their entirety, a portion of the 24th floor, and certain other space as
hereinafter set forth (the "Demised Premises") at the Building, as shown on
Exhibit A annexed hereto and made a part hereof, and Sublessor desires to
sublease the Demised Premises to Subtenant upon the terms and conditions
hereinafter set forth.

     NOW, THEREFORE, in consideration of the mutual covenants contained herein,
the parties agree as follows:

     1.   DEFINED TERMS. Each capitalized term not otherwise defined herein
shall have the meaning ascribed to it in the Overlease.

     2.   DEMISE AND TERM.

     A.   For and during the term established below, Sublessor leases to
Subtenant the Demised Premises, consisting of 362,155 rentable square feet
("RSF of the Demised Premises") of space at the Building. The leasing of the
Demised Premises by Subtenant shall include the right of Subtenant (a) to
access the Building common areas in common with the other tenants in the
Building and (b) to use all fixtures, improvements and betterments owned or
leased by Overlandlord which, at

<PAGE>   2
any time during the term of this Sublease, are attached to or installed in the
Demised Premises, all subject to such restrictions, rules, regulations, security
arrangements and charges (if any) as are provided for in the Overlease.

     B. The term (subject to extension as provided herein, the "Term") of this
Sublease shall commence on May 19, 2001 (the "Commencement Date") and expire on
November 17, 2021 (the "Expiration Date"), unless sooner canceled or otherwise
terminated as provided in this Sublease.

     C. Sublessor shall have a one time right to cancel this Sublease effective
as of May 31, 2011 by giving written notice (the "Sublessor Cancellation
Notice") to Subtenant by no later than May 1, 2008, time being of the essence as
to the giving of such notice, which notice shall state that Sublessor
unconditionally elects to cancel this Sublease effective as of May 31, 2011. In
the event Sublessor fails to timely deliver a Sublessor Cancellation Notice in
compliance herewith, and unless Subtenant has delivered the Subtenant
Cancellation Notice (as hereinafter defined), this Sublease shall continue until
the Expiration Date, unless otherwise terminated as provided in this Sublease.
In the event Sublessor timely delivers a Sublessor Cancellation Notice in
compliance herewith, the Expiration Date as defined herein shall for all
purposes mean May 31, 2011.

     D. Subtenant shall have a one time right to cancel this Sublease effective
as of May 31, 2011 by giving written notice (the "Subtenant Cancellation
Notice") to Sublessor by no later than April 1, 2008, time being of the essence
as to the giving of such notice, which notice shall state that Subtenant
unconditionally elects to cancel this Sublease effective as of May 31, 2011. In
the event Subtenant fails to timely deliver a Subtenant Cancellation Notice in
compliance herewith, and unless Sublessor has delivered the Sublessor
Cancellation Notice, this Sublease shall continue until the Expiration Date,
unless otherwise terminated as provided in this Sublease. In the event Subtenant
timely delivers a Subtenant Cancellation Notice in compliance herewith, the
Expiration Date as defined herein shall for all purposes mean May 31, 2011.

     E. In the event that Sublessor cancels this Sublease pursuant to Article
2.C hereof, Sublessor shall pay to Subtenant, by no later than June 30, 2011, an
amount (the "Sales Price") equal to twenty-five percent (25%) of the unamortized
value (as of May 31, 2011) of the leasehold improvements (the "Remaining
Lease-hold Improvements") which remain in the Demised Premises following
Subtenant's vacation of the Demised Premises on May 31, 2011; provided, however,
that solely for the purpose of calculating the Sales Price, Remaining Leasehold
Improvements

                                       2
<PAGE>   3
shall be deemed to exclude (i) all improvements made to the Demised Premises
after Subtenant's initial occupancy of any part thereof, (ii) all computer
equipment, cabinetry, racks and cabling, (iii) all improvements comprising the
trading floor or operation, except to the extent Sublessor makes substantial use
of such trading floor or operation after May 31, 2011, without making
substantial additional improvements thereto and (iv) any other leasehold
improvement which Sublessor, in its reasonable discretion, determines to be
obsolete or unusable to Sublessor. Sublessor and Subtenant acknowledge that the
Sales Price shall only be due and payable in connection with a cancellation of
this Sublease pursuant to Section 2.C. hereof, and no such payment shall be
required in connection with any other cancellation or termination hereof.
Subtenant shall be required to pay all New York State and New York City transfer
taxes and sales and compensating use taxes, if any, due in connection with the
payment of the Sales Price.

     3.   REQUIRED PROVISIONS.

     A.   The sale, pledge, transfer or other alienation of (a) a controlling
interest of the issued and outstanding capital stock of Subtenant (if a
corporation, unless such stock is publicly traded on any recognized security
exchange or over-the-counter market) or (b) any controlling interest in
Subtenant (if a partnership, limited liability company or joint venture),
however accomplished, and whether in a single transaction or in a series of
related or unrelated transactions, shall be deemed for the purposes of Section
11.03 of the Overlease to be an assignment of this Sublease which shall require
the prior consent of Owner in each instance.

     B.   Except as otherwise expressly set forth herein, any rights granted to
Sublessor to assign its rights under the Overlease and any obligations of
Sublessor related thereto, as set forth in Section 11.05A of the Overlease are
hereby granted to and binding upon Subtenant.

     C.   Except as otherwise expressly set forth herein, any rights granted to
Sublessor to sublet or permit occupancy of the "Demised Premises" (as defined in
the Overlease) and any obligations of Sublessor related thereto, as set forth in
Subsection 11.05B of the Overlease are hereby granted to and binding upon
Subtenant.

     D.   Nothing contained in this Section 3 shall be deemed a consent by the
Owner to any assignment or subletting by Subtenant and the terms of the
Overlease shall govern the requirement to obtain Owner's consent with respect
thereto.

                                       3
<PAGE>   4
     4.   Use. A.   Subtenant may use the Demised Premises as general and
administrative offices, uses incidental thereto and any other use expressly
permitted by the Overlease, subject in any event to the provisions of the
Overlease and this Sublease, and for no other purpose.

     B.   Subtenant agrees and acknowledges that space identified on Exhibit C
as shared space ("Shared Space") and facilities identified on Exhibit C as
shared facilities ("Shared Facilities") are subject to use and enjoyment by both
Sublessor and Subtenant as set forth on Exhibit C, and Subtenant's occupancy and
use rights with respect thereto are not exclusive of Sublessor, except where
Exhibit C indicates that a portion of the Shared Space is to be for Subtenant's
exclusive usage (the "Subtenant's Exclusive Shared Space"). In addition to all
other amounts payable hereunder by Subtenant, Subtenant shall pay to Sublessor
in advance, commencing on the Rent Commencement Date and thereafter on the first
day of each month during the Term, Subtenant's proportionate share (the "Shared
Proportionate Share") of the "Fixed Rent" payable under Section 1.03 of the
Overlease attributable to the Shared Space and Shared Facilities (the "Shared
Space and Facilities Rent"), which proportionate share shall initially be as set
forth on Exhibit C. Subtenant shall pay when billed therefor, as additional rent
hereunder, its Shared Proportionate Share of the cost of the repair, maintenance
and, in the case of fuel oil, replenishment (on a cost basis) of the Shared
Space and Shared Facilities and all additional rent, including, without
limitation, Tenant's Public Purpose Payments, Operating Expenses, Office
Cleaning Costs, Deemed Rental under the Ground Lease, Capital Sum, Theater
Surcharge and all other sums of money, payable to Sublessor to Overlandlord with
respect thereto.

     C.   Subtenant hereby agrees that Sublessor possesses the exclusive right
to control, operate, alter and repair the Shared Space and Shared Facilities.
Subtenant shall not have the right to make any alteration to the Shared Space or
Shared Facilities without Sublessor's prior written consent, which consent may
be granted or withheld at Sublessor's sole discretion. In the event Sublessor
consents to an alteration requested by Subtenant, such alteration shall be
performed by Sublessor at the sole cost and expense of Subtenant. Subtenant
shall pay all costs and expenses incurred by Sublessor in connection with any
such alteration within ten (10) days of Sublessor's request therefor. Sublessor
shall have the right to modify the Shared Proportionate Share, from time to
time, to reflect changes in the relative use by Sublessor and Subtenant of the
Shared Space and Shared Facilities.

     D.   Sublessor and Subtenant hereby agree to promptly establish a Joint
Operations Committee (the "Committee") composed of two (2) representatives of
Sublessor and two (2) representatives of Subtenant (each representative, a "Mem-


                                       4
<PAGE>   5
ber"). Sublessor hereby designates Glenn Elliott and Subtenant hereby designates
Frank Wallace as its initial representative on the Committee. Sublessor and
Subtenant shall each designate one additional representative to serve on the
Committee promptly following the execution hereof. Sublessor shall have the
right to designate alternative representatives for the Committee provided that
in no event shall Sublessor have the right to have more than two representatives
on the Committee at any time. Subtenant shall have the right to designate
alternative representatives for the Committee provided that in no event shall
Subtenant have the right to have more than two representatives on the Committee
at any time. To the extent any operational issue (each, an "Operational Issue")
at the Building materially affects the operation or use by Subtenant, or the
appearance, of the Demised Premises or the Shared Space and Shared Facilities,
Subtenant shall have the right to submit any concerns with respect thereto to
the Committee. The Committee shall review Subtenant's concerns and determine if
a course of action, other than that being taken by Sublessor, is warranted.
Committee determinations shall require the affirmative vote of three Members of
the Committee and shall be binding upon Sublessor and Subtenant. In reviewing
the Operational Issue the Committee shall take into account all special
considerations which may be unique to Sublessor or Subtenant and shall not
direct any action to be taken which would have a material adverse affect on
either Sublessor or Subtenant. In the event the Committee determines that the
Operational Issue requires a course of action, other than that being taken by
Sublessor (a "Sublessor's Approach"), such action shall be taken by Sublessor
(each, a "Required Action"). Together with each determination of a Required
Action the Committee shall determine whether the Required Action is necessary
because of special requirements or concerns of Subtenant, including, without
limitation, levels of service or maintenance required by Subtenant in excess of
that required by Sublessor. In the event the Required Action is determined to be
required as a result of such special requirements or concerns of Subtenant,
Subtenant shall reimburse Sublessor for the entire cost of such Required Action
within thirty (30) days of Sublessor's demand therefor, which demand shall be
delivered with reasonable details of the required expenditures. Absent such a
determination, costs of any Required Action shall be borne on a proportionate
basis as determined by the Committee. Subtenant shall reimburse Sublessor for
such proportionate share within thirty (30) days of Sublessor's demand therefor,
which demand shall be delivered with reasonable details of the required
expenditures. In the event Subtenant or Sublessor disagrees with any
determination of the Committee, each shall have the right, within thirty (30)
days of such determination, to submit such Operational Issue to arbitration in
accordance with Article 36 of the Overlease.

     5.   BASE RENT.

                                       5
<PAGE>   6
     A.   Subtenant shall pay to Sublessor, without notice or demand, and
without any right of offset or defense, in lawful money of the United States,
at the address set forth above or at such other address as Sublessor may by
notice designate, base rent (the "BASE RENT") as follows:

               (1)  for the period commencing on the Rent Commencement Date and
                    ending on May 31, 2011, all rent payable by Sublessor, under
                    the Overlease attributable to the Demised Premises,
                    including, without limitation, all "Fixed Rent" payable
                    under Section 1.03 of the Overlease, in accordance with
                    Exhibit A attached hereto and made part hereof; and

               (2)  for the period commencing on June 1, 2011 and ending on the
                    Expiration Date, an amount equal to the greater of (i) the
                    Fair Market Rent (as hereinafter defined) for the Demised
                    Premises, and (ii) all rent payable by Sublessor under the
                    Overlease attributable to the Demised Premises, including,
                    without limitation, all "Fixed Rent" payable under Section
                    1.03 of the Overlease.

As used herein the term "Fair Market Rent" shall mean the fair market value of
the Demised Premises determined as if the Demised Premises were available in the
then rental market for comparable first class market buildings in midtown
Manhattan and assuming that Sublessor has had a reasonable time to locate a
subtenant who rents with the knowledge of the uses to which the Demised Premises
can be adapted, and that neither Sublessor nor the prospective tenant is under
any compulsion to rent. The Fair Market Rent shall be determined by Sublessor
on the basis of the highest and best use of the Demised Premises assuming that
the Demised Premises are free and clear of all leases and tenancies (including
this Sublease), and, at the election of Sublessor, that the Demised Premises are
occupied by one (1) tenant or is subdivided and occupied by more than one (1)
tenant, whether improved or unimproved, taking into account all then existing
circumstances.

     B.   For purposes of determining the Fair Market Rent, the procedures set
forth on Exhibit E attached hereto and made a part hereof shall apply.


                                       6
<PAGE>   7
     C. Base Rent shall be payable in equal monthly installments in advance,
commencing on the Rent Commencement Date and thereafter on the first day of each
month during the Term, without counterclaim, setoff or deduction whatsoever.
Payment of the Base Rent and any additional rent shall be by Subtenant's check
or wire transfer of immediately available funds to the account identified to
Subtenant from time to time by Sublessor in writing.

     D. In addition to the Base Rent, Subtenant shall pay to Sublessor, as
additional rent hereunder, all additional rent payable by Sublessor under the
Overlease attributable to the Demised Premises for the period from the
Commencement Date (except as otherwise provided herein) through the Expiration
Date including, without limitation:

          (i)   commencing on the Rent Commencement Date, the Operating Expenses
                payable by Sublessor under the Overlease attributable to the
                Demised Premises;

          (ii)  commencing on the Rent Commencement Date, the Tenant's Cleaning
                Share of Office Cleaning Costs payable by Sublessor under the
                Overlease attributable to the Demised Premises, if applicable;

          (iii) commencing on the Rent Commencement Date, the portion of Deemed
                Rental under the Ground Lease payable by Sublessor under the
                Overlease attributable to the Demised Premises provided,
                however, that the calculation of Subtenant's portion of the
                Deemed Rent under the Ground Lease shall be determined as if the
                Deemed Rent under the Ground Lease was not reduced or otherwise
                adjusted for any Site 3 ESAC Reimbursements contemplated by the
                fourth sentence of Section 23.06.A. of the Overlease and the
                term "payable" as used in this clause (iii) shall mean the
                amount which would have been payable absent any such reduction;

          (iv)  commencing on the Rent Commencement Date, the Capital Sum
                payable by Sublessor under the Overlease attributable to the
                Demised Premises;

          (v)   the Tenant's Public Purpose Payments attributable to work
                performed in the Demised Premises or otherwise constituting


                                       7
<PAGE>   8
              Subtenant's proportionate share (based on RSF of the Demised
              Premises) of the other Public Purpose Payments payable by
              Sublessor under the Overlease; provided, however, that Subtenant
              shall not be obligated to pay such proportionate share with
              respect to Tenant's Public Purpose Payments due with respect to
              improvements made which do not benefit the Demised Premises (all
              payments made, or deemed made, by Subtenant pursuant to this
              clause (v) are hereinafter referred to as "Subtenant's Public
              Purpose Payments");

     (vi)     commencing on the Rent Commencement Date, Theatre Surcharge
              payable by Sublessor under the Overlease attributable to the
              Demised Premises; and

     (vii)    all other sums of money attributable to the Demised Premises as
              shall be payable by Sublessor to Overlandlord under the Overlease,
              including but not limited to all charges for services (including
              excess water usage charges, overtime HVAC and freight elevator
              charges and annual chilled water fees) pursuant to the Overlease
              (the "Additional Charges"), it being the intent of the parties
              hereto to provide a direct pass-through to Subtenant of all costs,
              expenses and payments payable by Sublessor under the Overlease
              attributable to the Demised Premises.

     Subtenant's share of Operating Expenses, Tenant's Cleaning Share of Office
Cleaning Costs (if applicable), Deemed Rental under the Ground Lease, Capital
Sum, Tenant's Public Purpose Payments, Theater Surcharge and Additional Charges
(collectively, the "Additional Rental") attributable to the Demised Premises
shall be payable in the same manner as provided in Article 4 of the Overlease
and shall be based on Overlandlord's statements, including estimates, rendered
to Sublessor with respect to such items, copies of which shall be delivered to
subtenant within ten (10) days of Sublessor's receipt thereof. To the extent
that any amounts paid by Subtenant on account of any of such items are based on
estimates provided by Overlandlord and exceed the amount actually due and
payable by Subtenant hereunder, such overpayment shall, in accordance with the
procedure by which overpayment of such an item is treated under the Overlease,
be either refunded to Subtenant or credited against the amounts next coming due
from Subtenant for the applicable item pursuant to this Section 5B; provided,
however, that if such overpayment shall have been credited to Subtenant and is
not fully reimbursed by such credit

                                       8


<PAGE>   9
prior to the expiration of the term of this Sublease, then, promptly following
the expiration or earlier termination of the term of this Sublease, Sublessor
shall, to the extent such amounts are received from Overlandlord, reimburse
Subtenant for the remaining balance of such overpayment less any amounts
Subtenant may owe to Sublessor upon the expiration of the term of this
Sublease. To the extent that any estimated amounts so paid by Subtenant are
less than the amount actually due and payable hereunder by Subtenant, Subtenant
shall within ten days after demand therefor pay the difference to Sublessor. If
any refund or credit results from an audit, challenge or other proceeding
instituted by Sublessor, Sublessor shall be entitled to first deduct from any
such refund or credit Sublessor's actual expenses incurred in connection with
obtaining such refund or credit and Subtenant shall be entitled to its
proportionate share of the net refund or credit. Subtenant's payments under
this Section 5B for any partial lease year shall be prorated on a per diem
basis. Subtenant shall be bound by any audit of such charges performed by or at
the request of Sublessor under the Overlease. Subtenant hereby acknowledges
that it shall not have any right to audit any of the books of, or statements
delivered by, Overlandlord in connection with this Sublease and any acceptance
of such statements, or settlements with respect thereto by Sublessor shall be
conclusive and binding upon Subtenant; provided, however, that Sublessor shall
not have the right to enter into settlements which disproportionately allocate
charges to the Demised Premises; provided further, however, that upon
Subtenant's request, Sublessor shall discuss the results of any such audit and
Sublessor's strategy for negotiating the same with Subtenant prior to entering
into any negotiations with Owner with respect thereto. The provisions of this
Section 5B shall survive the Expiration Date or sooner termination of this
Sublease.

     E.   As to any additional charges under the Overlease which are
attributable to the Demised Premises, such as, for example and without
limitation, charges under the Overlease for services furnished pursuant to the
Overlease to, or for repair of damage to, the Demised Premises, Subtenant shall
pay to Sublessor, as additional rent under this Sublease, within ten (10)
Business Days after receipt by Subtenant of the relevant statement (except that
when payment is due under the Overlease before ten (10) Business Days have
passed following Subtenant's receipt of the relevant statement, Subtenant shall
make such payment to Sublessor two (2) days prior to the date such payment is
due under the Overlease), an amount equal to its proportionate share of all
such charges. Sublessor shall provide Subtenant with copies of statements
received from Overlandlord evidencing such additional charges.

     F.   If Subtenant shall fail to pay any installment of Base Rent or any
additional rent when due and such failure shall continue for a period of three
(3)

                                       9
<PAGE>   10
Business Days after same shall have become due and payable, such unpaid amount
shall bear interest at the Prime Rate, from the due date until paid.

     G.   The term "rent" or "rents" as used in this Sublease shall mean the
Base Rent and all additional rent payable under this Sublease.

     6.   PUBLIC PURPOSE PAYMENTS.

     A.   To the extent Sublessor is entitled to receive, and receives,
payments from Overlandlord pursuant to Section 3.07.B.(iii)(a) of the
Overlease, Subtenant shall be entitled to receive from Sublessor an amount
equal to the lesser of (i) Subtenant's Public Purpose Payments made in
connection with the initial construction and fit-out of the Demised Premises
prior to occupancy thereof by Subtenant, and (ii) fifty percent (50%) of
Tenant's Priority Share (the "Subtenant Share Cap"); provided, however, in the
event the Tenant's Public Purpose Payments which do not comprise Subtenant's
Public Purpose Payments (the "Sublessor's Public Purpose Payments") made by
Sublessor are less than fifty percent (50%) of Tenant's Priority Share (such
difference the "Sublessor Deficiency"), the Subtenant Share Cap shall be
increased by such Sublessor Deficiency.

     B.   As used herein, the term "Sublessor Balance" shall mean the positive
difference, if any, between (i) the total of Sublessor's Public Purpose
Payments relating to the initial construction and fit-out of the Building, and
(ii) fifty percent of Tenant's Priority Share. As used herein, the term
"Subtenant Balance" shall mean the positive difference, if any, between (i) the
total of Subtenant's Public Purpose Payments relating to the initial
construction and fit-out of the Demised Premises, and (ii) fifty percent of
Tenant's Priority Share.

     C.   To the extent Sublessor is entitled to receive, and receives,
payments from Overlandlord pursuant to Section 3.07.B.(iii)(c) the source
of payment for which are Tenant's Public Purpose Payments relating to the
initial construction and fit-out of the Building prior to the occupancy thereof
by Sublessor and Subtenant (the total of such payments are hereinafter
referred to as the "Additional Reimbursements"), Subtenant shall be entitled to
receive from Sublessor an amount equal the product of the Additional
Reimbursements and a fraction, the numerator of which is the Subtenant Balance
and the denominator of which is the sum of (i) the Sublessor Balance, and (ii)
the Subtenant Balance.

     D.   In the event Subtenant is not required to pay Subtenant's Public
Purpose Payments because Overlandlord applies its ESAC's receivables as an
offset

                                       10
<PAGE>   11
against Public Purpose Payments pursuant to Section 3.07.B(vi) of the Overlease
(the "Overlandlord Election"), Subtenant shall pay to Sublessor within ten days
after each demand therefor, an amount equal to the difference between (i) the
amount of Subtenant's Public Purpose Payments that Subtenant would have been
obligated to pay but for Overlandlord's election, and (ii) the amount which
Subtenant would have been entitled to receive under Section 6A and Section 6C
hereof. Sublessor's calculation of all amounts relating to Tenant's Public
Purpose Payments, Sublessor's Public Purpose Payments, Subtenant's Public
Purpose Payments and the right to receive and make payments hereunder and under
the Overlease shall be binding and conclusive upon Sublessor and Subtenant
absent manifest error.

     E. Except as expressly set forth herein, Subtenant shall have no right to
receive any payments from Overlandlord or Sublessor with respect to Tenant's
Public Purpose Payments or Sublessor's Public Purpose Payments.

     7. SUBLEASE SUBJECT TO OVERLEASE.

     A. This Sublease is subject and subordinate to all of the terms, covenants
and conditions of the Overlease and to the matters to which the Overlease is or
shall be subordinate. A description of the Overlease is annexed hereto and made
a part hereof as Exhibit B. Subtenant shall not do, or permit to be done,
anything that would constitute a breach or violation of any term, covenant or
condition of the Overlease or the Building Rules promulgated thereunder or other
default under the Overlease on the part of Sublessor, as tenant thereunder.
Notwithstanding anything to the contrary contained in this Sublease, Subtenant
does not have any rights in respect of the Demised Premises greater than
Sublessor's rights under the Overlease.

     B. If for any reason the term of the Overlease shall end prior to the
Expiration Date of this Sublease, then, at the opinion of the Overlandlord,
either this Sublease shall terminate or Subtenant shall make full and complete
attornment to Overlandlord for the balance of this Sublease. Sublessor shall
deliver a copy of any default notice or other termination notice to Subtenant
within five (5) Business Days of Sublessor's receipt thereof. Sublessor shall
request from Overlandlord that Overlandlord obtain from each present or future
mortgagee and lessor under the Underlying Documents described on Schedule C to
the Overlease a Subordination, Non-Disturbance and Attornment Agreement for the
benefit of Subtenant; provided, however, that Sublessor makes no representation
or warranty that such agreement may be obtained. Sublessor and Subtenant
promptly shall furnish each other with a copy of any notice which either party
receives under any non-disturbance agreement in connection with the Demised
Premises.

                                       11
<PAGE>   12
     C.   To the extent that Sublessor has an obligation under the Overlease to
provide information, materials, documents or otherwise to cooperate with
Overlandlord in connection with Overlandlord's obtaining financing of the
Building, such obligations shall be obligations of Subtenant with respect to
Subtenant, its affiliates and the Demised Premises.

     8.   INCORPORATION BY REFERENCE. All of the terms, covenants and
conditions contained in the Overlease are incorporated by reference into this
Sublease, except where inconsistent with or modified by the terms of this
Sublease, and are also subject, without limitation, to the following specific
exceptions and/or modifications:

     A.   The following portions of the Overlease are not incorporated into
this Sublease but shall continue in full force and effect in the Overlease:

          (i)  Sections 1.01, 1.02 (exclusive of Section 1.02.C.), 1.03.A. and
     .B., 1.06.D. (to the extent of a right to remeasure; provided, however,
     that Sublessor shall allocate to Subtenant Subtenant's proportionate share
     of the adjustments made under clauses (i) through (iv) of such Section),
     1.06.E. and .F. (provided that Sublessor shall deliver to Subtenant copies
     of any instruments contemplated thereunder), 1.07, 1.08 and Clause (i) of
     2.01;

          (ii)  Clauses (iii)-(viii) of Section 3.07.B.;

          (iii)  Section 3.10; provided, however, that Sublessor shall be
     obligated to pay to Subtenant, as and when Sublessor receives the same
     from Overlandlord, the portion of Owner's Work Contribution attributable
     to the Demised Premises, as determined by Sublessor in its reasonable
     discretion;

          (iv)  Section 6.07 (provided that if the relevant Legal Requirement
     affects only the Demised Premises Sublessor shall exercise its rights
     under such Section at the request of Subtenant at Subtenant's sole cost
     and expense;

          (v)  Sections 19.07 and 19.08;

          (vi)  The fourth sentence of Section 23.06.A.;

          (vii)  Section 29.10 and Section 29.12; and



                                       12
<PAGE>   13
          (viii)  Articles 27, 28, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
     49 and 50.

          In addition to the foregoing, and notwithstanding anything to the
contrary contained herein or in the Overlease: (i) Subtenant's rights to
services, such as chilled water, shall be limited to Subtenant's pro rata share
of such services, and (ii) Subtenant's usage of the messenger center and shaft
space shall be governed by Section 4.B herein.

     B.   Wherever used in the Overlease, the words "Landlord" and "Tenant", or
words of similar import, shall be construed to mean, respectively, "Sublessor"
and "Subtenant"; provided, however, that the word "Landlord" in the Overlease
shall be construed to mean both "Sublessor" and "Overlandlord" in those Sections
of the Overlease providing for indemnification by Tenant and insurance coverage
required by Tenant; the word "Landlord" in the Overlease shall be construed to
mean only Overlandlord in those Section of the Overlease providing for
Landlord's services, Building construction, repairs and restoration, removal of
Building violations, operation of the Building, Landlord's insurance and the
like; the word "Lease", or words of similar import, shall be construed to mean
the "Sublease"; the words "fixed or base rent," or words of similar import,
shall be construed to mean the Base Rent; the words "additional charges" or
words of similar import shall be construed to mean additional rent; the word
"rent", or words of similar import, shall be construed to mean rent payable
under this Sublease; the word "Demised Premises" or "Premises" shall be
construed to mean the Demised Premises as defined in this Sublease; the words
"Tenant's Property" shall be construed to mean "Subtenant's Property;" the words
"term" or "Initial Term", "Commencement Date" or "Possession Date", and
"Expiration Date", or words of similar import, shall be construed to mean,
respectively, the Term and the dates set for the beginning and the end of the
term of this Sublease as provided in this Sublease; and the words "Rent
Commencement Date" shall be construed to mean the Rent Commencement Date as
defined in this Sublease.

     C.   To the extent possible, the provisions of the Overlease incorporated
by reference into this Sublease shall be construed as consistent with and
complementary to the other provisions of this Sublease, but in the event of any
inconsistency, the provisions of this Sublease shall control.

     D.   If Overlandlord shall default in the performance of any of its
obligations to Sublessor with respect to the Demised Premises, Subtenant shall
notify Sublessor in writing of the nature of the default in question and
request that


                                       13
<PAGE>   14
Sublessor enforce its rights against Overlandlord, but Sublessor shall have no
obligation to bring any action or proceeding or to take any steps to enforce
Sublessor's rights against Overlandlord. If, after written notice from
Subtenant, Sublessor shall fail or refuse to take appropriate action for the
enforcement of Sublessor's rights against Overlandlord with respect to the
Demised Premises within a reasonable time considering the nature of
Overlandlord's default, Subtenant shall have the right, at Subtenant's sole cost
and expense, to assert Sublessor's rights against Overlandlord, but only if
Subtenant (1) shall not then be in default under this Sublease, (2) shall give
notice to Sublessor before asserting any such rights against Overlandlord and
(3) shall defend, indemnify and hold Sublessor harmless from and against any and
all claims, actions, liabilities, losses, damages, costs and expenses
(including, but not limited to, reasonable attorneys' fees and disbursements)
which Sublessor may incur by reason of such assertion of rights by Subtenant
against Overlandlord. In connection with clause (3) of this subsection D,
Subtenant shall provide the required defense by counsel reasonably acceptable to
Sublessor and Sublessor shall not seek reimbursement from Subtenant for separate
counsel to Sublessor unless there is a conflict of interest or Subtenant is not
prosecuting the case to Sublessor's reasonable satisfaction. If in connection
with Subtenant asserting Sublessor's rights as permitted hereunder, any action
brought by Subtenant against Overlandlord is barred by reason of lack of
privity, Subtenant may take such action in Sublessor's name, and Sublessor shall
execute all documents in connection therewith provided the same is without cost
or expense to Sublessor and Subtenant shall fulfill and comply with the
conditions set forth in clauses (1), (2), and (3) of this subsection D.

     E.   In order to facilitate the coordination of the provisions of this
Sublease with those of the Overlease, unless otherwise stated herein, the time
periods contained in provisions of the Overlease that are incorporated by
reference into this Sublease and for which the same action must be or has been
taken under the Overlease (such as, for example and without limitation, the time
limit for the curing of a default under this Sublease that is also a default
under the Overlease), are changed for the purpose of incorporation by reference
by shortening or lengthening that period in each instance by three (3) Business
Days so that in each instance, Subtenant shall have that much less time to
observe or perform hereunder than Sublessor has as the tenant under the
Overlease and Sublessor shall have that much more time to observe, perform,
consent, approve, or otherwise act hereunder than the Overlandlord has under the
Overlease. Notwithstanding anything contained in this subsection to the
contrary, if the time period enumerated in the Overlease is three (3) Business
Days or less, the time for observance or performance hereunder shall be reduced
by one (1) Business Day.


                                       14
<PAGE>   15
     F.   Whenever the approval or consent of Overlandlord is required under any
provision of the Overlease or this Sublease, Subtenant shall be required to
obtain the written approval or consent of Sublessor and Sublessor shall endeavor
to obtain like approval or consent of Overlandlord. Whenever Sublessor has
agreed that a required approval or consent shall not be unreasonably withheld or
delayed (whether in this Sublease or pursuant to any provision of the Overlease
incorporated herein) it shall be deemed reasonable for Sublessor to withhold or
delay its approval or consent if Overlandlord shall have delayed or refused to
give any approval or consent which may be requested of it related to the same
matter. Sublessor shall have no liability for any failure or refusal on the part
of the Overlandlord to grant any such consent.

     9.   PERFORMANCE BY OVERLANDLORD. Subtenant will look solely to
Overlandlord for performance of the services and obligations specified in the
Overlease to be provided or performed by Overlandlord thereunder, including,
without limitation, heat, ventilating and air conditioning, utilities, repairs,
restoration, alterations, reimbursement, cleaning, elevator service, hot and
cold water and light bulb replacement. If Overlandlord shall default or delay in
the performance or observance of any of its agreements or obligations under the
Overlease (including, but not limited to, any obligation for the payment of
money or to perform or furnish any work, services or utilities at or to the
Demised Premises or the Building), Sublessor shall have no obligation, liability
or responsibility therefor to Subtenant and Sublessor shall be excused from the
performance or observance of the corresponding obligation, if any, which may be
owed by Sublessor to Subtenant under this Sublease. Any condition resulting from
such default or delay by Overlandlord shall not constitute an eviction, actual
or constructive, of Subtenant. No such default or delay shall excuse Subtenant
from the performance or observance of any of its obligations to be performed or
observed under this Sublease or shall entitle Subtenant to terminate this
Sublease or to any reduction in or abatement of the rent or other charges
provided for in this Sublease. In furtherance of the foregoing, Subtenant does,
to the extent permitted by law, and except for the willful misconduct or gross
negligence of Sublessor, hereby waive any cause of action and any right to bring
an action against Sublessor by reason of any act or omission of Overlandlord
under the Overlease.

     10.  CONDITION OF DEMISED PREMISES.

          Subtenant is leasing and accepts the Demised Premises "AS IS",
reasonable wear and tear, natural deterioration, and casualty damage expected.
Without limiting the generality of the foregoing, Sublessor shall have no
obligation


                                       15
<PAGE>   16
to make, supply or perform any alterations, services, material, fixtures,
equipment, or decorations to the Demised Premises. In entering into this
Sublease, Subtenant has relied solely on such investigations, examinations, and
inspections as Subtenant has chosen to make and Subtenant acknowledges that
Sublessor has afforded Subtenant the opportunity for full and complete
investigations, examinations, and inspections.

     11.  FIRE OR CASUALTY. A. If the Demised Premises or the Building (in such
a manner that materially interferes with Subtenant's use of the Demised Premises
or reasonable access thereto) shall be damaged, in whole or in part, by fire or
other casualty or condemned or taken in any manner for any public or
quasi-public use, the annual Base Rent paid under this Sublease shall be
reduced, in the same proportion, if any, and for the same period, in which the
annual fixed rent payable for the Demised Premises shall be reduced under the
Overlease (i.e., by way of example, if 50% of the annual fixed rent payable by
Sublessor under the Overlease for a particular floor included in the Demised
Premises is abated, then Subtenant shall be entitled to a 50% abatement in the
annual Base Rent hereunder allocable to that floor). Sublessor shall not be
responsible for restoration nor for any inconvenience or annoyance to Subtenant
or injury to Subtenant's business resulting in any way from such damage or the
repair or restoration or for such condemnation. This Sublease will continue in
full force and effect, subject to the foregoing provisions and subject to
Sublessor's rights and the rights of Overlandlord to terminate the Overlease.

          B. In the event that a casualty occurs to a portion of the Demised
Premises which, if such portion were not the subject of this Sublease, would
give rise to a right of Sublessor under the Overlease to terminate the Overlease
as to that portion as an Earlier Termination Floor under Section 9.05.F(ii) of
the Overlease or as a Damaged Floor under Section 9.08 of the Overlease,
Subtenant shall have the right under this Sublease to terminate this Sublease as
to that portion of the Demised Premises by delivering to Sublessor written
notice of its election to effect such partial termination, effective as of the
last day on which Sublessor may effectively terminate the Overlease as to such
portion under such Section. Any such notice shall be effective only if delivered
to Sublessor within a time period which allows Sublessor no fewer than ten days
to deliver due and timely notice to Overlandlord under the applicable Section of
the Overlease of Sublessor's election to terminate the Overlease as to such
portion of the Demised Premises. In the event that Subtenant timely delivers
such notice otherwise in accordance with this Section 10.B., this Sublease shall
terminate as to such portion as of the date specified in such notice and the
further provisions of Section 9.08 of the Overlease shall be applicable to this
Sublease and to Subtenant and Sublessor hereunder, mutatis mutandis.



                                       16
<PAGE>   17
          C. Anything contained in this Section 10 to the contrary
notwithstanding, in the event that a casualty occurs to the "Demised Premises"
(as defined in the Overlease) giving rise to a right of Sublessor to terminate
the Overlease, Sublessor shall have the right to exercise such right in its
sole discretion. Sublessor shall, within five (5) Business Days of its receipt
of a notice of termination from Overlandlord, deliver a copy of the same to
Subtenant. Sublessor shall have no liability to Subtenant, or anyone claiming
through Subtenant, for exercising any such option to terminate the Overlease.

          D. In the event that a casualty or other damage occurs to any material
portion of the Demised Premises, Subtenant shall deliver prompt written notice
thereof to Sublessor.

     12. ASSIGNMENT AND SUBLETTING.

     A. Subtenant shall not, without the prior written consent of Sublessor
(which shall not be unreasonably withheld or delayed), assign, sell, mortgage,
pledge, or in any manner transfer this Sublease or any interest therein, or
permit any of the foregoing to occur involuntarily, by operation of law, or
otherwise, or sublet the Demised Premises or any part or parts thereof, grant
any concession or license, or otherwise permit occupancy of all or any part of
the Demised Premises by any person other than Subtenant. Those provisions of
Article 8 of the Overlease which relate to Overlandlord's consent requirements
and Overlandlord's rights and obligations in connection with any subletting or
assignment are specifically incorporated herein and acknowledged by Subtenant.

     B. Notwithstanding anything contained herein to the contrary, provided
that Subtenant is not then in default under this Sublease, except as set forth
in Section 12E hereof, Subtenant may without the consent of Sublessor or
Overlandlord and without Sublessor's right to recapture as hereinafter
provided, sublet the Demised Premises or assign this Sublease to the extent
that Sublessor would have the right to sublet the "Demised Premises" (as
defined in the Overlease) or assign the Overlease under Section 11.05.A. or
11.05.B. of the Overlease, as applicable, provided that Subtenant fulfills the
conditions and complies with the provisions of such Sections of the Overlease
as incorporated in this Sublease by Sections 3.D. and 3.E.

     C. Notwithstanding anything contained herein to the contrary, except for
sublettings and assignments permitted without the consent of Sublessor as
provided in Section 11.B. hereof, if Subtenant desires to assign this Lease or
sublet the Demised Premises it shall request Sublessor's consent in a written
notice ("Subten-



                                       17
<PAGE>   18
ant's Request Notice"), which shall contain all of the material terms relating
to such assignment or subletting and Sublessor shall have the right (the
"Recapture Right") to recapture the portion of the Demised Premises Subtenant
wishes to sublet or assign by either terminating this Sublease or subleasing
back the Demised Premises from Subtenant (such sublease, the "Recapture
Sublease") at the lower of (i) the proposed sublet rental as set forth in
Subtenant's Request Notice or (ii) the rent provided for in this Sublease.
Sublessor shall exercise the Recapture Right by giving notice (the "Recapture
Notice") to Subtenant within thirty (30) days after receipt by Sublessor of
Subtenant's Request Notice. The effective date of the termination or the
Recapture Sublease shall be the date set forth in Subtenant's Request Notice as
the effective date of the proposed sublease or assignment. The Recapture
Sublease shall be in a form reasonably acceptable to Subtenant and Sublessor and
shall expressly (i) give Sublessor the absolute right, without Subtenant's
permission, to assign the Recapture Sublease and to further sublet all or any
part of the Demised Premises and to make any and all changes, alterations and
improvements therein and (ii) negate any intention that the estate created under
the Recapture Sublease be merged with any other estate held by either Subtenant
or Sublessor. Performance by Sublessor, or any assignee or subtenant of
Sublessor, under the Recapture Sublease shall be deemed performance by Subtenant
of any similar obligation under this Sublease and Subtenant shall not be liable
for any default under this Sublease or deemed to be in default hereunder if such
default is occasioned by or arises from any act or omission of Sublessor, or any
assignee or subtenant of Sublessor, or is occasioned by or arises from any act
or omission of any occupant of the Demised Premises.

     D. The consent by Sublessor to any assignment, subletting or other transfer
of the Lease or the Demised Premises shall not constitute the consent of
Overlandlord thereto, and shall not be construed to relieve Subtenant from
obtaining the consent of Sublessor and Overlandlord to any other or further
assignment, subletting or transfer to the extent required by this Sublease or
the Overlease. No assignment, subletting (except for a Recapture Sublease to the
extent provided in Section 11C hereof) or other transfer shall release Subtenant
from the full performance of the obligations under this Sublease.

     E. Subtenant shall not have the right to enter into any sublease (i) which
demises only a portion of the premises leased by Subtenant on any floor of the
Building, unless the excluded portion of the premises comprises Shared Space, or
(ii) which demises or allows the use of any Shared Space.

     F. Subtenant shall not be required to share with Sublessor any profits
which Subtenant realizes in connection with any assignment or subletting
permitted

                                       18
<PAGE>   19
hereunder; provided however, that Subtenant shall be obligated to pay to
Sublessor all, or the portion, of such profits which shall be payable to
Overlandlord pursuant to the Overlease. Subtenant acknowledges that in
calculating such profits the provisions of Section 11.03 of the Overlease shall
apply and accordingly, the space being sublet by Subtenant may be deemed to be
another part of the Demised Premises for determining Overlandlord's right to
receive all or any portion of such profits.

     13.  SUBLESSOR'S RIGHT TO RECAPTURE.

          In the event that Subtenant ceases to meet the definition of an
"affiliate" of Sublessor's (as such term is defined in Section 11.05.A. of the
Overlease), Sublessor shall have the right to terminate this Sublease with
respect to that amount of rentable square footage required for Sublessor to be
deemed under the Overlease to lease at least four hundred thousand (400,000)
square feet. The area of the Demised Premises to be terminated (the "Area")
shall be reasonably determined by Subtenant, who hereby agrees that the Area
shall be contiguous and easily accessed by Sublessor.

     14.  INSURANCE.

          Upon thirty (30) days' notice, Subtenant shall pay to Sublessor,
Subtenant's pro rata share (based on a fraction, the numerator of which is the
RSF of the Demised Premises and the denominator of which is the total square
footage leased by Sublessor under the Overlease) of all of Sublessor's costs to
procure and maintain all insurance required by the terms of the Overlease.

          If at any time Sublessor ceases to own at least fifty-one percent
(51%) of Subtenant within thirty (30) days thereafter, Subtenant shall procure
and maintain all insurance necessary for Subtenant to comply with the insurance
requirements imposed upon Sublessor as "Tenant" under Article 19 of the
Overlease as incorporated herein. Such insurance shall name Sublessor as an
additional insured, in addition to the other entities which are required to be
named as additional insureds pursuant to the Overlease. Subtenant shall furnish
Sublessor and Overlandlord with certificates evidencing such insurance prior to
the expiration of such thirty (30) day period.



                                       19
<PAGE>   20

     15.  ALTERATIONS.

     A.  Subtenant shall not make any Alterations at the Demised Premises,
except in accordance with the provisions of the Overlease incorporated herein by
reference in Section 7 hereof. In addition to such provisions, the following
shall apply to any Alterations proposed to be performed by Subtenant:

          (i)    Sublessor's consent shall be deemed given if Overlandlord
     consents to the Alteration in question; provided, however, that Sublessor
     shall have the right to withhold consent to an Alteration to which
     Overlandlord has otherwise consented if, in Sublessor's reasonable opinion,
     such Alteration may adversely affect the risers serving Sublessor's space
     or the building systems or other infrastructure serving Sublessor's space;

          (ii)   Subtenant shall not make any alterations which affect the
     structural integrity of the Demised Premises, require slab penetration,
     affect electrical systems or require plumbing installation or work to be
     performed within Proximity (as hereinafter defined) of any space set forth
     on Exhibit D (each a "Specialty Location") without obtaining the prior
     written consent of Sublessor, which consent Sublessor shall have the right
     to grant or withhold in Sublessor's sole discretion. As used herein the
     term "Proximity" shall mean all space located on the floor above (from slab
     to slab) any Specialty Location to the extent such space is either directly
     above, or within ten feet of any space which is directly above, a Specialty
     Location. For example, if a Specialty Location is comprised of one square
     foot of area on the tenth floor of the Building, Proximity shall mean that
     same square foot on the eleventh floor, together with all space on the
     eleventh floor which is within ten feet of such square foot on the eleventh
     floor, from the floor slab to the ceiling slab of the eleventh floor.

          (iii)  Subtenant shall deliver to Sublessor all plans, drawings,
     instruments, documents, certificates and other items required to be
     delivered to Overlandlord under the Overlease, and Sublessor shall
     prosecute the approval procedures with Overlandlord on Subtenant's behalf
     with the degree of attention and diligence Sublessor would exercise if
     doing the same on its own account, including without limitation invoking,
     at Subtenant's request, the consent dispute resolution mechanisms provided
     in the Overlease;

          (iv)   Sublessor shall have the right to approve, in its reasonable
     discretion, Subtenant's contractors and other providers of labor for the


                                       20














<PAGE>   21
     proposed Alteration in the event such proposed Alteration may affect the
     risers serving Sublessor's space or otherwise affect building systems or
     other infrastructure serving Sublessor's space;

     B.   Except as provided to the contrary in the Overlease, all Alterations
installed in the Demised Premises at any time, either by Subtenant or by
Sublessor or Overlandlord on Subtenant's behalf, shall be the property of
Subtenant during the term of this Sublease and, upon expiration of earlier
termination of the term of this Sublease, shall become the property of
Sublessor and shall remain upon and be surrendered with the Demised Premises
unless the terms of any consent Sublessor shall have given to Subtenant in
connection therewith shall expressly have required their removal or their
removal is required pursuant to the Overlease, in which event the same shall be
removed from the Demised Premises by Subtenant, at Subtenant's sole cost and
expense, at or prior to the expiration of the Term of this Sublease. Upon
removal of any item as may be permitted or required hereunder, Subtenant shall
immediately, and at its sole cost and expense, repair any damage to the Demised
Premises or the Building due to such removal. All property permitted or
required to be removed by Subtenant at the end of the Term remaining in the
Demised Premises shall be deemed abandoned and may, at the election of
Sublessor, either be retained as Sublessor's property or be removed from the
Demised Premises by Sublessor at Subtenant's expense. Except as provided to the
contrary in the Overlease, all furniture, furnishings, trade fixtures and other
items of movable personal property shall be the property of Subtenant and
nothing contained herein shall be construed as prohibiting Subtenant from
removing same from the Demised Premises.

     16.  SIGNAGE.

     A.   Sublessor hereby grants Subtenant the right to utilize a
proportionate share (as reasonably determined by Sublessor) of the Revenue
Generating Signage and Non-Revenue Generating Signage (the "Signage") granted
to Sublessor pursuant to the Overlease, from time to time. Subtenant shall be
entitled to one-half (50%) of the revenue derived from the commercial
exploitation thereof, as such commercial exploitation is permitted in Section
42.01.H(ii) of the Overlease; provided, however, that the determination as to
whether to commercially exploit such signage shall be made by Sublessor in
Sublessor's sole and absolute discretion. Subtenant's right to utilize the
Signage is subject to the reasonable rules, regulations, requirements and
limitations of Sublessor. Sublessor shall exercise exclusive control over the
installation, operation, maintenance, repair, exploitation and alteration of
the Signage (including the operation of any Signage control room). Subtenant
shall be obligated

                                       21
<PAGE>   22
to pay Sublessor an amount equal to Subtenant's proportionate share of the
costs and expenses incurred by Sublessor in connection with the signage
(including all payments Sublessor is required to make to Overlandlord in
connection with retaining all rights to the signage) within ten (10) days of
Sublessor's request therefor. Subtenant shall lose its right to utilize the
Signage and share in any revenue derived therefrom from and after the date
Subtenant occupies less than fifty thousand (50,000) rentable square feet of
space in the Building.

     B.   Subtenant shall not, and hereby expressly acknowledges that Subtenant
shall not, have any right or interest in or to any rights of first offer or
rights to Building Top Signage granted to Sublessor pursuant to Article 42 of
the Overlease.

     17.  Electricity, Cleaning Service.

     A.   Commencing on the Commencement Date or such later date on which
Sublessor first becomes liable for payments on account of electricity at the
Demised Premises either to Overlandlord under the Overlease or to the utility
provider if Sublessor has obtained direct metering, Subtenant shall pay to
Sublessor each month an amount equal to the cost for all electricity and energy
provided to, and/or consumed within, the Demised Premises. Such amount shall be
based upon the demand and consumption of electricity at the Demised Premises as
shown on a meter or submeter to be installed by Sublessor or Overlandlord on
each floor of the Demised Premises fully occupied by Subtenant, which amount
shall be computed and paid in accordance with the provisions of the Overlease.
In the event any portion of the Demised Premises is not separately metered for
any reason, Subtenant shall reimburse Sublessor for all costs incurred
by Sublessor with respect to the electricity and energy furnished to such
portions of the Demised Premises, which costs shall be reasonably determined by
Sublessor. It is the intent of Sublessor and Subtenant that Subtenant pay all
costs of electricity furnished to the Demised Premises without any cost or
profit being incurred or made by Sublessor with respect thereto.

     B.   In the event Sublessor elects to contract directly for cleaning
service, Subtenant may elect to (i) contract directly for cleaning service in
accordance with Article 29.03.I. of the Overlease with respect to the Demised
Premises, whereby Subtenant shall assume all the rights and obligations of
"Tenant" thereunder with respect to the Demised Premises, or (ii) request that
the Demised Premises be cleaned by Sublessor's cleaning service and be included
in Sublessor's cleaning contract. Subtenant shall pay as additional rent to
Sublessor, within ten (10) Business Days after receiving a statement therefor,
its proportionate share, as reasonably determined by Sublessor, of all costs
incurred under such contract.

                                       22
<PAGE>   23
     18.  REPRESENTATIONS AND WARRANTIES.

     A.   Subtenant hereby represents and warrants to Sublessor that the person
signing this Sublease on behalf of Subtenant has the full right and authority
to execute this Sublease on behalf of Subtenant, and that this Sublease
constitutes a valid and binding obligation of Subtenant enforceable against
Subtenant in accordance with its terms except as enforcement may be limited by
applicable bankruptcy, insolvency, reorganization, moratorium or other similar
laws affecting creditors' rights generally and by general principles of equity
(regardless of whether enforcement is sought in equity or at law). Sublessor
hereby represents and warrants to Subtenant that the person signing this
Sublease on behalf of Sublessor has the full right and authority to execute
this Sublease on behalf of Sublessor, and that this Sublease constitutes a
valid and binding obligation of Sublessor enforceable against Sublessor in
accordance with its terms except as enforcement may be limited by applicable
bankruptcy, insolvency, reorganization, moratorium or other similar laws
affecting creditors' rights generally and by general principles of equity
(regardless of whether enforcement is sought in equity or at law).

     B.    Sublessor hereby represents and warrants that (i) Sublessor is the
holder of the interest of the tenant under the Overlease; (ii) the Overlease is
in full force and effect and, to the best of Sublessor's knowledge,
Overlandlord is not in default thereunder; and (iii) Sublessor, to the best of
its knowledge, is not in material default, and has received no written notice
that it is in default, under the Overlease.

     19.   SUBTENANT'S AND SUBLESSOR'S ADDITIONAL COVENANTS. Subtenant also
covenants as follows:

     A.    Subtenant hereby assumes and agrees to perform and comply with all
of the terms, covenants and conditions of the Overlease on the part of the
tenant thereunder to be performed and observed as they relate to the Demised
Premises, other than as expressly set forth in this Sublease.

     B.    Subtenant will not do or cause to be done or suffer or permit any
act or thing to be done or suffered which would or might constitute a default
under the Overlease or cause the Overlease or the rights of Sublessor, as
tenant thereunder, to be terminated or which would or might cause Sublessor to
become liable for any damages, costs, claims or penalties or would or might
increase the fixed rent, additional rent or other charges or obligations of
Sublessor, as tenant under the


                                      23




<PAGE>   24
Overlease, or would or might adversely affect or reduce any of Sublessor's
rights or benefits under the Overlease.

     C.   Subtenant shall defend, indemnify and hold Sublessor and any guarantor
of Sublessor's obligations as tenant under the Overlease harmless from and
against any and all claims, actions, liabilities, losses, damages, costs and
expenses (including, without limitation, reasonable attorneys' fees and
disbursements) arising from the use or occupancy by Subtenant of the Demised
Premises or the Building or from any work or thing done or any condition created
by or any other act or omission of Subtenant or its employees, agents,
contractors, visitors or licensees, in or about the Demised Premises or an other
part of the Building, or from any breach of its obligations under this Sublease.
The provisions of this subsection C shall survive the expiration or earlier
termination of this Sublease.

     D.   Sublessor and Subtenant each promptly shall furnish to the other
copies of any notices of default given by Overlandlord to Sublessor or
Subtenant, as the case may be.

     20.  REMEDIES. If Subtenant defaults in the performance of any of the
terms, covenants or conditions of this Sublease or the Overlease beyond any
applicable notice and cure period, Sublessor shall be entitled to exercise any
and all of the rights and remedies to which it is entitled at law or in equity,
and also any and all of the rights and remedies specifically provided for in the
Overlease with the same force and effect as if herein specifically set forth in
full, and wherever in the Overlease rights and remedies are given to
Overlandlord, the same shall be deemed to refer to Sublessor.

     21.  BROKER. Sublessor and Subtenant each represent and warrant to the
other that it dealt with no broker in connection with this Sublease. Subtenant
hereby agrees to indemnify and hold Sublessor harmless from and against any and
all claims for commission, fee or other compensation and all liabilities, suits,
costs and expenses (including, without limitation, reasonable attorneys' fees
and disbursements) arising out of any breach of the above representation and
warranty. Sublessor hereby agrees to indemnify and hold Subtenant harmless from
and against any and all claims for commission, fee or other compensation and all
liabilities, suits, costs and expenses (including, without limitation,
reasonable attorneys' fees and disbursements) arising out of any breach of the
above representation and warranty. Sublessor shall have no liability for any
brokerage commissions arising out of a further sublease, assignment or other
transfer by Subtenant. The provisions of this Article shall survive the
expiration or sooner termination of this Sublease.


                                       24
<PAGE>   25
     22.  NOTICES. All notices, requests, approvals, waivers, consents,
deliveries, payments or other communications ("Notices") that either party is
required or desires to send to the other in connection with this Sublease shall
be in writing, duly executed by the party sending the notice, and sent by (i)
hand delivery, against a signed receipt, (ii) certified or registered mail,
return receipt requested, or (iii) a nationally recognized overnight courier
service providing a signed receipt of delivery, addressed as follows: (a) if to
Subtenant, (1) prior to the date on which Subtenant takes occupancy for the
conduct of its business (the "Subtenant's Occupancy Date"), to Subtenant's
address set forth at the beginning of this Sublease and (2) from and after the
Subtenant's Occupancy Date, to its address at the Demised Premises, or to such
other address as Subtenant shall then have designated for that purpose by
notice to Sublessor, and (b) if to Sublessor, to Sublessor's address set forth
at the beginning of this Sublease or to such other address as Sublessor shall
then have designated for that purpose by notice to Subtenant. Notices shall be
deemed delivered when received or, if delivery is made and refused, when such
delivery is made. In connection with any action or proceeding brought by
Sublessor against Subtenant under this Sublease, Sublessor shall serve
Subtenant with a copy of the summons, complaint or other appropriate papers at
the Demised Premises.

     23.  QUIET ENJOYMENT. Provided that Subtenant is not in default hereunder,
Subtenant may peaceably and quietly enjoy the Demised Premises, subject to the
Overlease and all matters to which the Overlease is subject and the terms and
conditions of this Sublease.

     24.  SECURITY DEPOSIT. Subtenant hereby covenants and agrees to pay
Sublessor an amount equal to Subtenant's proportionate share (as reasonably
determined by Sublessor) of the cost of procuring the Letter of Credit
deposited with Overlandlord (or the holder of Overlandlord's Mortgage) at the
time of the execution and delivery of the Overlease, which amount shall be
payable on the execution and delivery hereof. In addition thereto, on the
commencement of each lease year commencing on May 19, 2001, Subtenant shall pay
Sublessor an amount equal to the product of (i) the product of (1) One Hundred
and Twenty Million Dollars ($120,000,000) and (2) a fraction, the numerator of
which is the RSF of the Demised Premises and the denominator of which is the
total square footage leased by Sublessor pursuant to the Overlease and (ii)
fifty basis points (.5%) during each year of the Term, provided however, that
Subtenant shall not be obligated to pay such amount for any full lease year for
which it has posted the New Letter of Credit (as hereinafter defined). If at
any time Sublessor ceases to own at least fifty-one percent (51%) of Subtenant
("Control Cessation"), Subtenant shall, within thirty (30) days' of



                                       25
<PAGE>   26
such Control Cessation deliver to Sublessor an unconditional, irrevocable and
transferable letter of credit in form and substance acceptable to Sublessor (the
"New Letter of Credit"), issued by and drawn on a bank satisfactory to Sublessor
and which is a member of the New York Clearing House for the account of
Sublessor, for a term expiring on July 31, 2011, in an amount equal to the
product of (i) One Hundred and Twenty Million Dollars ($120,000,000) and (ii) a
fraction, the numerator of which is the RSF of the Demised Premises and the
denominator of which is the total square footage lease by Sublessor pursuant to
the Overlease. If Subtenant defaults in respect of any of the terms, provisions
and conditions of this Sublease, Sublessor may present the New Letter of Credit
for payment and apply or retain the whole or any part of the proceeds thereof,
to the extent required for the payment of any rent or for any sum which
Sublessor may expend or be required to expend by reason of Subtenant's default.
If Sublessor applies or retains any part of the proceeds of the New Letter of
Credit, Subtenant, upon demand, shall deposit with Sublessor the amount so
applied or retained so that Sublessor shall have the full deposit on hand at all
times during the Term. If Subtenant shall fully and faithfully comply with all
of the terms,  provisions, covenants and conditions of this Sublease, the New
Letter of Credit shall be returned to Subtenant after the Expiration Date and
after delivery of possession of the entire Demised Premises to Sublessor.

     25.  TERMINATION OF OVERLEASE. Subject to the provisions of Section 6B
hereof, in the event of and upon the termination or cancellation of the
Overlease pursuant to any of the provisions thereof, whether or not the
Commencement Date of this Sublease shall have occurred, this Sublease shall
automatically expire and terminate and shall be of no further force and effect,
and Subtenant shall have no claim against Sublessor of any kind whatsoever.
Sublessor shall, within five (5) Business Days of its receipt of a notice of
termination from Overlandlord, deliver a copy of the same to Subtenant.

     26. RIGHTS TO EXPANSION SPACE. In the event (i) Sublessor is offered the
right to lease additional space in the Building pursuant to an option contained
in the Overlease, (ii) Sublessor elects not to lease any such additional space
for its own use, and (iii) the Overlease would permit Sublessor to lease such
space for occupancy by Subtenant, Sublessor shall notify Subtenant in writing
(an "Expansion Notice") of the availability of such space and the terms
applicable to the leasing thereof to the extent known by Sublessor, and the date
by which Owner must be notified of Sublessor's election. Subtenant shall have
until the date which is five (5) days prior to the date upon which Sublessor
must notify Owner of its decision to elect to lease such space. In the event
Subtenant notifies Sublessor that it elects to lease such space, Sublessor shall
take such steps as are necessary to lease such additional space from Owner on



                                       26


<PAGE>   27
behalf of Subtenant. Upon the leasing of any such additional space pursuant to
Subtenant's direction, this Sublease shall automatically be deemed amended to
include such space; provided that (x) Subtenant shall be responsible for all
costs and expenses, including, without limitation, all rent and additional rent
due with respect of such additional space, (y) the term of this Sublease with
respect to such additional space only shall be coterminous with the lease of
such additional space, and (z) all terms and provisions of the Overlease
applicable to such additional space shall be deemed incorporated such that
Subtenant shall have all of the obligations pertaining thereto. Sublessor shall
not be liable to Subtenant in any respect for Owner's failure to lease such
additional space to Sublessor or for any other failure by Owner with respect to
such additional space.

     27.  NO RIGHT TO RENEWAL OPTIONS.  Notwithstanding anything to the
contrary contained in this Sublease, the term of this Sublease shall not be
extended for any reason including, without limitation, Sublessor's election to
extend the term of the Overlease pursuant to Article 41 thereof or otherwise.

     28.  SURRENDER.  Upon the expiration or other termination of this
Sublease, Subtenant shall quit and surrender the Demised Premises, broom clean,
in good order and condition, ordinary wear and tear and damage by fire or other
casualty excepted, vacant and free of all of its property and otherwise in
accordance with  the terms and conditions of this Sublease and the Overlease.
Subtenant's obligations under the provision shall survive the expiration or
earlier termination of this Sublease.

     29.  NO WAIVER.  The failure of either party to insist upon the strict
performance or observance of any obligation of the other party under this
Sublease or to exercise any right or other remedy under or with respect to this
Sublease shall not be construed as a waiver or relinquishment for the future of
that obligation, right or other remedy of either party. Sublessor's receipt and
acceptance of any rent, or acceptance of performance by Sublessor of any
obligation, with knowledge of Subtenant's breach or default under this
Sublease, shall not be construed as a waiver of that breach or default. No
waiver by either party of any provision of this Sublease shall be deemed to
have been made unless specifically expressed in a writing signed by the waiving
party.

     30.  NO ORAL CHANGE.  This Sublease cannot be changed orally or in any
manner other than by a written agreement executed by both parties.

                                       27
<PAGE>   28
     31.  SUCCESSORS AND ASSIGNS. Except as may be otherwise specifically
provided in this Sublease, the provisions of this Sublease shall extend to,
bind and inure to the benefit of the parties hereto and their respective
personal representatives, heirs, successors and permitted assigns. In the event
of any assignment or transfer of Sublessor's interest in the Overlease,
Sublessor shall be released and discharged from all covenants, conditions and
agreements of Sublessor under this Sublease arising from and after the
effective date of such assignment or transfer; provided, however, that such
covenants, conditions and agreements arising from and after the effective date
of such assignment or transfer shall be deemed to be assumed by and to be
binding upon such assignee or transferor.

     32.  INTERPRETATION.

     A.   This Sublease shall be governed by and construed in accordance with
the laws of the State of New York.

     B.   If any provision of this Sublease or the application thereof to any
person or circumstance shall, for any reason and to any extent, be invalid or
unenforceable, the remainder of this Sublease and the application of that
provision to other persons or circumstances shall not be affected but rather
shall be enforced to the fullest extent permitted by law.

     C.   The captions, headings and titles contained in this Sublease, if any,
are solely for convenience of reference and shall not affect its interpretation.

     D.   This Sublease shall be construed without regard to any presumption or
other rule requiring construction against the party causing this Sublease to be
drafted.

     33.  EXECUTION AND DELIVERY. The submission to Subtenant of this Sublease
shall not constitute an option or offer for the subleasing of the Demised
Premises, and the execution and/or delivery of this Sublease by Subtenant shall
have no binding force or effect on Sublessor unless and until Sublessor and
Subtenant shall have (i) executed this Sublease, and (ii) delivered a
fully-executed counterpart to each other.

     34.  COUNTERPARTS. This Sublease may be executed in one or more
counterparts, each of which shall constitute an original hereof and all of
which, taken together, shall constitute one and the same instrument.

                                       28
<PAGE>   29
     IN WITNESS WHEREOF, Sublessor and Subtenant have executed and delivered
this Sublease as of the date first above written.

SUBLESSOR:                              REUTERS C CORP.

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





SUBTENANT:                              INSTINET GLOBAL HOLDINGS, INC.

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



                                       29