Document:

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                          REGISTRATION RIGHTS AGREEMENT

                                     between

                                  eSpeed, INC.

                                       and

                           THE INVESTORS NAMED HEREIN

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                                TABLE OF CONTENTS

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                                                                            ----

RECITALS.......................................................................1

ARTICLE I
      DEMAND REGISTRATIONS.....................................................1
      1.1   Requests for Registration..........................................1
      1.2   Number of Demand Registrations; Expenses...........................2
      1.3   Effective Registration Statement...................................2
      1.4   Priority on Demand Registrations...................................2
      1.5   Subsequent Registration Rights.....................................2

ARTICLE II
      PIGGYBACK REGISTRATIONS..................................................3
      2.1   Right to Piggyback.................................................3
      2.2   Piggyback Expenses.................................................3
      2.3   Priority on Primary Registrations..................................3
      2.4   Priority on Secondary Registrations................................3

ARTICLE III
      HOLDBACK AGREEMENTS......................................................4

ARTICLE IV
      REGISTRATION PROCEDURES..................................................4

ARTICLE V
      REGISTRATION EXPENSES....................................................6
      5.1   Registration Expenses..............................................6
      5.2   Sellers' Expenses..................................................7

ARTICLE VI
      UNDERWRITTEN OFFERINGS...................................................7
      6.1   Demand Underwritten Offerings......................................7
      6.2   Incidental Underwritten Offerings..................................7

ARTICLE VII
      INDEMNIFICATION..........................................................7
      7.1   Company's Indemnification Obligations..............................7
      7.2   Holder's Indemnification Obligations...............................8

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      7.3   Notices; Defense; Settlement.......................................9
      7.4   Indemnity Provision...............................................10
      7.5   Contribution Based on Relative Fault..............................10
      7.6   Payments..........................................................11

ARTICLE VIII
      PARTICIPATION IN UNDERWRITTEN REGISTRATIONS.............................11

ARTICLE IX
      DEFINITIONS.............................................................11
      9.1   Terms.............................................................11
      9.2   Defined Terms in Corresponding Sections...........................13

ARTICLE X
      MISCELLANEOUS...........................................................13
      10.1  Remedies..........................................................13
      10.2  Amendments and Waivers............................................14
      10.3  Successors and Assigns............................................14
      10.4  Notices...........................................................14
      10.5  Headings..........................................................15
      10.6  Gender............................................................15
      10.7  Invalid Provisions................................................15
      10.8  Governing Law.....................................................15
      10.9  Counterparts......................................................15
      10.10  Deferral.........................................................15
      10.11 Additional Investors..............................................16

ARTICLE XI
      RULE 144 REPORTING......................................................16

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            REGISTRATION RIGHTS AGREEMENT (this "Agreement") dated as of
December 9, 1999 between eSpeed, Inc., a Delaware corporation (the "Company"),
and the other parties that have executed the signature pages hereto (the
"Initial Investors") or otherwise execute a joinder agreement and become a party
hereto (collectively, the "Investors").

                                    RECITALS

            WHEREAS, the Company and the Initial Investors have entered into an
Assignment and Assumption Agreement, dated as of the date hereof, pursuant to
which the Company issued certain securities to each of the Initial Investors;

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

                                    ARTICLE I
                              DEMAND REGISTRATIONS

            1.1 Requests for Registration. Subject to Sections 1.2 and 1.3
hereof, the Required Investors may request, in writing, registration under the
Securities Act of all or part of their Registrable Securities. Within twenty
(20) days after receipt of any such request, the Company will give notice of
such request to all other Investors. Thereafter, the Company will use all
reasonable efforts to effect the registration under the Securities Act (i) on
Form S-1 or any similar long-form registration statement (a "Long-Form
Registration") or (ii) on Form S-3 or any similar short-form registration
statement (a "Short-Form Registration") if the Company qualifies to effect a
Short Form Registration, and will include in such registration all Registrable
Securities with respect to which the Company has received written requests for
inclusion therein within twenty (20) days after the receipt of the Company's
notice, subject to the provisions of Section 1.4. All registrations requested
pursuant to this Section 1.1 are referred to herein as "Demand Registrations".
The Company shall not be required to effect any Demand Registration requested by
a Required Investor if either (a) within the six (6) months preceding the
receipt by the Company of such request, the Company has filed a registration
statement to which the Piggyback Registration rights set forth in Article II
hereof apply or (b) such Required Investor may sell all of the Registrable
Securities requested to be included in such Demand Registration without
registration under the Securities Act, pursuant to the exemption provided by (i)
Rule 144(k) under the Securities Act, as such rule may be amended from time to
time, or (ii) any similar rule or regulation hereafter adopted by the
Commission.

            1.2 Number of Demand Registrations; Expenses. Subject to Sections
1.1 and 1.3 hereof, the Required Investors shall be entitled to an aggregate of
three (3) Demand
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Registrations, with no more than one (1) of such Demand Registrations being a
Long-Form Registration; provided, however, that the Company need not effect any
requested Demand Registration unless the expected proceeds of such registration
exceed $1,000,000. The Company will pay all Registration Expenses in connection
with any Demand Registration, including any Registration Statement that is not
deemed to be effected pursuant to the provisions of Section 1.3 hereof.

            1.3 Effective Registration Statement. A registration requested
pursuant to Section 1.1 of this Agreement shall not be deemed to have been
effected (i) unless a Registration Statement with respect thereto has been
declared effective by the Commission, (ii) if after it has become effective,
such registration is interfered with by any stop order, injunction or other
order or requirement of the Commission or other governmental agency or court for
any reason, and, as a result thereof, the Registrable Securities covered thereby
have not been sold or (iii) the Registration Statement does not remain effective
for a period of at least 180 days beyond the effective date thereof or, with
respect to an underwritten offering of Registrable Securities, until ninety (90)
days after the commencement of the distribution by the holders of the
Registrable Securities included in such Registration Statement. If a
registration requested pursuant to this Article I is deemed not to have been
effected as provided in this Section 1.3, then the Company shall continue to be
obligated to effect the number of Demand Registrations set forth in Section 1.2
without giving effect to such requested registration.

            1.4 Priority on Demand Registrations. If the Company includes in any
underwritten Demand Registration any securities which are not Registrable
Securities and the managing underwriters advise the Company in writing that in
their opinion the number of Registrable Securities and other shares of Common
Stock proposed to be included exceeds the number of Registrable Securities and
other securities which can be sold in such offering, the Company will first
include in such registration, to the exclusion of any other securities, the
number of Registrable Securities requested to be included which, in the opinion
of such underwriters, can be sold, pro rata among the Investors on the basis of
the amount of Registrable Securities requested to be offered thereby.

            1.5 Subsequent Registration Rights. From and after the date of this
Agreement, in the event the Company shall, without the written consent of a
majority of the holders of Registrable Securities, enter into any agreement with
holders or a prospective holder of any securities of the Company giving such
holder or prospective holder registration rights the terms of which are more
favorable in the aggregate than the registration rights granted to the holders
of Registrable Securities hereunder, the Company shall notify the holders of
Registrable Securities of such more favorable terms and this agreement shall be
modified to reflect such terms.

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                                   ARTICLE II
                             PIGGYBACK REGISTRATIONS

            2.1 Right to Piggyback. Following the closing of the Public
Offering, whenever the Company proposes to register any of its equity securities
under the Securities Act (other than pursuant to a Demand Registration and other
than for use in a Rule 145 transaction or for registrations for employee plans)
and the registration form to be used may be used for the registration of
Registrable Securities (a "Piggyback Registration"), the Company will give
notice to all Investors of its intention to effect such a registration and will
include in such registration all Registrable Securities with respect to which
the Company has received written requests for inclusion therein within fifteen
(15) days after the receipt of the Company's notice, subject to the provisions
of Section 2.3 and 2.4 hereof. Such requests for inclusion shall specify the
number of Registrable Securities intended to be disposed of and the intended
method of distribution thereof.

            2.2 Piggyback Expenses. The Registration Expenses of the Investors
will be paid by the Company in all Piggyback Registrations.

            2.3 Priority on Primary Registrations. If a Piggyback Registration
is an underwritten primary registration on behalf of the Company, and the
managing underwriters advise the Company that in their opinion the number of
securities requested to be included in such registration exceeds the number
which can be sold in such offering, the Company will include in such
registration (i) first, the securities the Company proposes to sell, (ii)
second, that number of the Registrable Securities proposed to be included in
such registration, pro rata among the respective holders thereof based upon the
total number of shares which such holders proposed to include in such
registration and (iii) that number of other shares of Common Stock proposed to
be included in such registration, pro rata among the respective holders thereof
based upon the total number of shares which such holders propose to include in
such registration.

            2.4 Priority on Secondary Registrations. If a Piggyback Registration
is not a Demand Registration pursuant to Article I hereof but is an underwritten
secondary registration on behalf of holders (other than the Investors) of the
Company's securities, and the managing underwriters advise the Company that in
their opinion the number of securities requested to be included in such
registration exceeds the number which can be sold in such offering, the Company
will include in such registration (i) first, the number of shares of Common
Stock requested to be included by holders and (ii) second, the Registrable
Securities requested to be included in such registration by the Investors pro
rata based upon the number of shares which such Investors requested to be
included.

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                                   ARTICLE III
                               HOLDBACK AGREEMENTS

            Holdback Obligations. Each holder of Registrable Securities agrees
not to effect any public sale or distribution of equity securities of the
Company, or any securities convertible, exchangeable or exercisable for or into
such securities, during the seven (7) days prior to, and the 90-day period
beginning on, the effective date of any underwritten Demand Registration (except
as part of such underwritten registration), unless (i) the managing underwriters
of the registered public offering otherwise agree or (ii) the executive
officers, directors and 10% stockholders of the Company shall not be similarly
restricted.

                                   ARTICLE IV
                             REGISTRATION PROCEDURES

            Whenever holders of Registrable Securities have requested that any
Registrable Securities be registered pursuant to this Agreement, the Company
will use reasonable efforts to effect the registration and the sale of such
Registrable Securities in accordance with the intended method of disposition
thereof as quickly as possible, and pursuant thereto the Company will as
expeditiously as reasonably possible:

            (a) prepare and file with the Commission a Registration Statement
with respect to such Registrable Securities and use all reasonable efforts to
cause such Registration Statement to become and remain effective until the
completion of the distribution contemplated thereby; provided, that as promptly
as practicable before filing a Registration Statement or Prospectus or any
amendments or supplements thereto, the Company will (i) furnish to counsel
selected by the holders of Registrable Securities copies of all such documents
proposed to be filed and (ii) notify each holder of Registrable Securities
covered by such Registration Statement of (x) any request by the Commission to
amend such Registration Statement or amend or supplement any Prospectus, or (y)
any stop order issued or threatened by the Commission, and take all reasonable
actions required to prevent the entry of such stop order or to promptly remove
it if entered;

            (b) (i) prepare and file with the Commission such amendments and
supplements to such Registration Statement and the Prospectus used in connection
therewith as may be necessary to keep such Registration Statement effective
until all Registrable Securities covered by such Registration Statement are sold
in accordance with the intended plan of distribution set forth in such
Registration Statement and (ii) comply with the provisions of the Securities Act
with respect to the disposition of all securities covered by such Registration
Statement during such period in accordance with the intended methods of
disposition by the sellers thereof set forth in such Registration Statement;

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            (c) furnish to each seller of Registrable Securities, without
charge, such number of conformed copies of such Registration Statement, each
amendment and supplement thereto, the Prospectus included in such Registration
Statement (including each preliminary Prospectus and, in each case including all
exhibits) and such other documents as such seller may reasonably request in
order to facilitate the disposition of the Registrable Securities owned by such
seller;

            (d) use all reasonable efforts to register or qualify such
Registrable Securities under such other securities or blue sky laws of such
jurisdictions in the United States as any seller thereof shall reasonably
request, to keep such registration or qualification in effect for so long as
such Registration Statement remains in effect and do any and all other acts and
things which may be reasonably necessary or advisable to enable such seller to
consummate the disposition in such jurisdictions of the Registrable Securities
owned by such seller; provided, however, that the Company will not be required
to (i) qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this clause (d), (ii) subject itself to
taxation in any such jurisdiction or (iii) consent to general service of process
in any such jurisdiction;

            (e) use all reasonable efforts (if the offering is underwritten) to
furnish to each seller of Registrable Securities a signed copy, addressed to
such seller (and the underwriters, if any) of an opinion of counsel for the
Company or special counsel to the selling stockholders, dated the effective date
of such Registration Statement (and, if such Registration Statement includes an
underwritten public offering, dated the date of the closing under the
underwriting agreement), covering substantially the same matters with respect to
such Registration Statement (and the Prospectus included therein) as are
customarily covered in opinions of issuer's counsel delivered to the
underwriters in underwritten public offerings, and such other legal matters as
the seller (or the underwriters, if any) may reasonably request;

            (f) notify each seller of Registrable Securities, at a time when a
Prospectus relating thereto is required to be delivered under the Securities
Act, of the happening of any event known to the Company as a result of which the
Prospectus included in such Registration Statement, as then in effect, contains
an untrue statement of a material fact or omits to state any fact required to be
stated therein or necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading, and, at the request of
any such seller, the Company will prepare and furnish such seller a reasonable
number of copies of a supplement to or an amendment of such Prospectus as may be
necessary so that, as thereafter delivered to the purchasers of such Registrable
Securities, such Prospectus shall not include an untrue statement of a material
fact or omit to state a material fact required to be stated therein or necessary
to make the statements therein, in the light of the circumstances under which
they were made, not misleading;

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            (g) cause all such Registrable Securities to be listed on each
securities exchange and quotation system on which similar securities issued by
the Company are then listed and, if such securities are not then listed on a
national securities exchange or the Nasdaq Stock Market, cause them to be so
listed or qualified; provided, that the Company then meets or is reasonably
capable of meeting the eligibility requirements for such an exchange or system
and such exchange or system is reasonably satisfactory to the managing
underwriters, and to enter into such customary agreements as may be required in
furtherance thereof, including, without limitation, listing applications and
indemnification agreements in customary form;

            (h) provide a transfer agent and registrar for all such Registrable
Securities not later than the effective date of such Registration Statement;

            (i) make available for inspection by any seller of Registrable
Securities, any underwriter participating in any disposition pursuant to such
Registration Statement and any attorney, accountant or other agent retained by
any such seller or underwriter, all financial and other records, pertinent
corporate documents and properties of the Company, and cause the Company's
officers, directors, employees and independent accountants to supply all
information reasonably requested by any such seller, underwriter, attorney,
accountant or agent in connection with such Registration Statement to enable
them to conduct a reasonable investigation within the meaning of the Securities
Act;

            (j) subject to other provisions hereof, use all reasonable efforts
to cause such Registrable Securities covered by such Registration Statement to
be registered with or approved by such other governmental agencies or
authorities or self-regulatory organizations as may be necessary to enable the
sellers thereof to consummate the disposition of such Registrable Securities;
and

            (k) promptly notify the holders of the Registrable Securities of the
issuance of any stop order by the Commission or the issuance by any state
securities commission or other regulatory authority of any order suspending the
qualification or exemption from qualification of any of the Registrable
Securities under state securities or "blue sky" laws, and use every reasonable
effort to obtain the lifting at the earliest possible time of any stop order
suspending the effectiveness of any Registration Statement or of any order
preventing or suspending the use of any preliminary Prospectus.

                                    ARTICLE V
                              REGISTRATION EXPENSES

            5.1 Registration Expenses. All registration and filing fees, fees
and expenses of compliance with securities or blue sky laws (including the fees
and expenses of counsel in connection with blue sky qualifications of the
Registrable Securities), printing expenses, listing fees for securities to be
registered on a national securities exchange or the Nasdaq Stock Market

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and all independent certified public accountants, underwriters (excluding
discounts and commissions) and other Persons retained by the Company and
reasonable fees and expenses of one counsel to the holders representing more
than 50% of the Registrable Securities registered in connection with the subject
registration (all such expenses being herein called "Registration Expenses"),
will be borne as provided in Sections 1.2 and 2.2 of this Agreement.

            5.2 Sellers' Expenses. The Company shall have no obligation to pay
any underwriting discounts or commissions attributable to the sale of Registered
Securities, which expenses will be borne by all sellers of securities included
in such registration in proportion to the aggregate selling price of the
securities to be so registered.

                                   ARTICLE VI
                             UNDERWRITTEN OFFERINGS

            6.1 Underwriting Agreement. If requested by the underwriters for any
underwritten offering of Registrable Securities pursuant to a Demand
Registration, the Company will enter into an underwriting agreement with such
underwriters for such offering, such agreement to contain such representations
and warranties by the Company and such other terms as are generally included in
agreements of this type, including, without limitation, indemnities customarily
included in such agreements. The holders of the Registrable Securities will
cooperate in good faith with the Company in the negotiation of the underwriting
agreement.

            6.2 Obligations of Participants in Underwritten Offerings. No Person
may participate in any underwritten registration hereunder unless such Person
(i) agrees to sell such Person's securities on the basis provided in any
underwriting arrangements approved by the Person or Persons entitled hereunder
to approve such arrangements and (ii) completes and executes all questionnaires,
powers of attorney, indemnities, underwriting agreements, escrow agreements and
other documents required under the terms of such underwriting arrangements and
consistent with the provisions of this Agreement.

                                   ARTICLE VII
                                 INDEMNIFICATION

            7.1 Company's Indemnification Obligations. The Company agrees to
indemnify and hold harmless each of the holders of any Registrable Securities
covered by any Registration Statement referred to herein and each other Person,
if any, who controls such holder within the meaning of Section 15 of the
Securities Act or Section 20 of the Exchange Act (collectively, the "Holder
Indemnitees"), as follows:

                  (i) against any and all loss, liability, claim, damage or
            expense arising out of or based upon an untrue statement or alleged
            untrue statement of a material

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            fact contained in any Registration Statement (or any amendment or
            supplement thereto), including all documents incorporated therein by
            reference, or in any preliminary Prospectus or Prospectus (or any
            amendment or supplement thereto) or the omission or alleged omission
            therefrom of a material fact required to be stated therein or
            necessary to make the statements therein, in the light of the
            circumstances under which they were made, not misleading;

                  (ii) against any and all loss, liability, claim, damage and
            expense to the extent of the aggregate amount paid in settlement of
            any litigation, investigation or proceeding by any governmental
            agency or body, commenced or threatened, or of any claim based upon
            any such untrue statement or omission or any such alleged untrue
            statement or omission, if such settlement is effected with the
            written consent of the Company; and

                  (iii) against any and all expense incurred by them in
            connection with investigating, preparing or defending against any
            litigation, or investigation or proceeding by any governmental
            agency or body, commenced or threatened, or any claim based upon any
            such untrue statement or omission or any such alleged untrue
            statement or omission, to the extent that any such expense is not
            paid under clause (i) or (ii) above;

provided, that this indemnity does not apply to any loss, liability, claim,
damage or expense to the extent arising out of an untrue statement or alleged
untrue statement or omission or alleged omission made in reliance upon and in
conformity with information furnished to the Company by or on behalf of any
holder expressly for use in the preparation of any Registration Statement (or
any amendment or supplement thereto), including all documents incorporated
therein by reference, or in any preliminary Prospectus or Prospectus (or any
amendment or supplement thereto); and provided further, that the Company will
not be liable to any holder or any other Holder Indemnitee under the indemnity
agreement in this Section 7.1 with respect to any preliminary Prospectus or the
final Prospectus or the final Prospectus as amended or supplemented, as the case
may be, to the extent that any such loss, liability, claim, damage or expense of
such Holder Indemnitee results from the fact that such holder sold Registrable
Securities to a Person to whom there was not sent or given, at or prior to the
written confirmation of such sale, a copy of the final Prospectus or of the
final Prospectus as then amended or supplemented, whichever is most recent, if
the Company has previously and timely furnished copies thereof to such holder.

            7.2 Holder's Indemnification Obligations. In connection with any
Registration Statement in which a holder of Registrable Securities is
participating, each such holder agrees to indemnify and hold harmless (in the
same manner and to the same extent as set forth in Section 7.1 of this
Agreement) the Company and each Person, if any, who controls the Company within
the meaning of Section 15 of the Securities Act or Section 20 of the Exchange
Act with respect to any statement or alleged statement in or omission or alleged
omission from

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such Registration Statement, any preliminary, final or summary Prospectus
contained therein, or any amendment or supplement thereto, if such statement or
alleged statement or omission or alleged omission was made about such holder in
reliance upon and in conformity with information furnished to the Company by or
on behalf of such holder. The obligations of each holder pursuant to this
Section 7.2 are to be several and not joint; provided, that, with respect to
each claim pursuant to this Section 7.2, each such holder's maximum liability
under this Section shall be limited to an amount equal to the net proceeds
actually received by such holder (after deducting any underwriting discount and
expenses) from the sale of Registrable Securities being sold pursuant to such
Registration Statement or Prospectus by such holder.

            7.3 Notices; Defense; Settlement. Promptly after receipt by an
indemnified party hereunder of written notice of the commencement of any action
or proceeding involving a claim referred to in Section 7.1 or Section 7.2 of
this Agreement, such indemnified party will, if a claim in respect thereof is to
be made against an indemnifying party, give written notice to the latter of the
commencement of such action; provided, that the failure of any indemnified party
to give notice as provided herein shall not relieve the indemnifying party of
its obligations under Section 7.1 or Section 7.2 of this Agreement except to the
extent that the indemnifying party is actually prejudiced by such failure to
give notice. In case any such action is brought against an indemnified party,
the indemnifying party will be entitled to participate in and to assume the
defense thereof, jointly with any other indemnifying party similarly notified,
to the extent that it may wish, with counsel reasonably satisfactory to such
indemnified party, and after notice from the indemnifying party to such
indemnified party of its election so to assume the defense thereof, the
indemnifying party will not be liable to such indemnified party for any legal or
other expenses subsequently incurred by the latter in connection with the
defense thereof, unless in such indemnified party's reasonable judgment a
conflict of interest between such indemnified and indemnifying parties may exist
in respect of such claim, in which case the indemnifying party shall not be
liable for the fees and expenses of (i) more than one counsel for all holders of
Registrable Securities, selected by the Required Investors or (ii) more than one
counsel for the Company in connection with any one action or separate but
similar or related actions. An indemnifying party who is not entitled to, or
elects not to, assume the defense of a claim will not be obligated to pay the
fees and expenses of more than one counsel for all parties indemnified by such
indemnifying party with respect to such claim, unless in the reasonable judgment
of any indemnified party a conflict of interest may exist between such
indemnified party and any other of such indemnified parties with respect to such
claim, in which event the indemnifying party shall be obligated to pay the fees
and expenses of such additional counsel or counsels. The indemnifying party will
not, without the prior written consent of each indemnified party, settle or
compromise or consent to the entry of any judgment in any pending or threatened
claim, action, suit or proceeding in respect of which indemnification may be
sought hereunder (whether or not such indemnified party or any Person who
controls such indemnified party is a party to such claim, action, suit or
proceeding), unless such settlement, compromise or consent includes an
unconditional release of such indemnified party from all liability arising out
of such claim, action, suit or proceeding. Notwithstanding anything to the
contrary set forth herein, and without

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limiting any of the rights set forth above, in any event any party will have the
right to retain, at its own expense, counsel with respect to the defense of a
claim.

            7.4 Indemnity Provision. The Company and each holder of Registrable
Securities requesting registration shall provide for the foregoing indemnity
(with appropriate modifications) in any underwriting agreement with respect to
any required registration or other qualification of securities under any Federal
or state law or regulation of any governmental authority other than the
Securities Act.

            7.5 Contribution Based on Relative Fault. If the indemnification
provided for in Sections 7.1 and 7.2 of this Agreement is unavailable or
insufficient to hold harmless an indemnified party under such Sections, then
each indemnifying party shall contribute to the amount paid or payable by such
indemnified party as a result of the losses, claims, damages or liabilities
referred to in Section 7.1 or Section 7.2 of this Agreement in such proportion
as is appropriate to reflect the relative fault of the indemnifying party on the
one hand, and the indemnified party on the other, in connection with statements
or omissions which resulted in such losses, liabilities, claims, damages or
expenses, as well as any other relevant equitable considerations, including,
without limitation, the relative benefits received by each party from the
offering of the securities covered by such Registration Statement, the parties'
relative knowledge and access to information concerning the matter with respect
to which the claim was asserted and the opportunity to correct and prevent any
statement or omission. The relative fault shall be determined by reference to,
among other things, whether the untrue or alleged untrue statement of a material
fact or the omission or alleged omission to state a material fact relates to
information supplied by the indemnifying party or the indemnified party and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such untrue statements or omission. The parties hereto agree
that it would not be just and equitable if contributions pursuant to this
Section 7.5 were to be determined by pro rata or per capita allocation (even if
the underwriters were treated as one entity for such purpose) or by any other
method of allocation which does not take account of the equitable considerations
referred to in the first sentence of this Section 7.5. The amount paid by an
indemnified party as a result of the losses, claims, damages or liabilities
referred to in the first sentence of this Section 7.5 shall be deemed to include
any legal or other expenses reasonably incurred by such indemnified party in
connection with investigating or defending any action or claim (which shall be
limited as provided in Section 7.3 of this Agreement if the indemnifying party
has assumed the defense of any such action in accordance with the provisions
thereof) which is the subject of this Section 7.5. Promptly after receipt by an
indemnified party under this Section 7.5 of notice of the commencement of any
action against such party in respect of which a claim for contribution may be
made against an indemnifying party under this Section 7.5, such indemnified
party shall notify the indemnifying party in writing of the commencement thereof
if the notice specified in Section 7.3 of this Agreement has not been given with
respect to such action; provided, that the omission to so notify the
indemnifying party shall not relieve the indemnifying party from any liability
which it may otherwise have to any indemnified party under this Section 7.5,
except to the extent that the indemnifying party is actually prejudiced by such
failure to give notice. The Company

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and each holder of Registrable Securities agrees with each other and the
underwriters of the Registrable Securities, if requested by such underwriters,
that (i) the underwriters' portion of such contribution shall not exceed the
underwriting discount and (ii) that the amount of such contribution shall not
exceed an amount equal to the net proceeds actually received by such
indemnifying party from the sale of Registrable Securities in the offering to
which the losses, liabilities, claims, damages or expenses of the indemnified
parties relate. No Person guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any Person who was not guilty of such fraudulent
misrepresentation.

            7.6 Payments. The indemnification required by this Article VII shall
be made by periodic payments of the amount thereof during the course of the
investigation or defense, as and when bills are received or expense, loss,
damage or liability is incurred.

                                  ARTICLE VIII
                                   DEFINITIONS

            8.1 Terms. As used in this Agreement, the following defined terms
shall have the meanings set forth below:

            "Business Day" means a day other than Saturday, Sunday or any day on
which banks located in the State of New York are authorized or obligated to
close.

            "Class A Common Stock" means the Class A Common Stock, par value
$.01 per share, of the Company and any securities into which the Class A Common
Stock shall have been changed or any securities resulting from any
reclassification or recapitalization of the Class A Common Stock.

            "Class B Common Stock" means the Class B Common Stock, par value
$.01 per share, of the Company and any securities into which the Class B Common
Stock shall have been changed or any securities resulting from any
reclassification or recapitalization of the Class B Common Stock.

            "Commission" means the U.S. Securities and Exchange Commission.

            "Exchange Act" means the Securities Exchange Act of 1934, as
amended, or any similar Federal statute then in effect, and any reference to a
particular section thereof shall include a reference to the equivalent section,
if any, of any such similar Federal statute, and the rules and regulations
thereunder.

            "Person" means any individual, corporation, partnership,
association, trust or other entity or organization, including a government or
political subdivision or an agency or instrumentality thereof.

                                       11
<PAGE>

            "Prospectus" means the Prospectus included in any Registration
Statement (including without limitation, a Prospectus that disclosed information
previously omitted from a Prospectus filed as part of an effective Registration
Statement in reliance upon Rule 430A promulgated under the Securities Act), as
amended or supplemented by any Prospectus supplement, with respect to the terms
of the offering of any portion of the securities covered by such Registration
Statement, and all other amendments and supplements to the Prospectus, including
post-effective amendments, and all material incorporated by reference or deemed
to be incorporated by reference in such Prospectus.

            "Public Offering" means the consummation of the initial underwritten
public offering of Class A Common Stock registered under the Securities Act of
1933, as amended.

            "Registrable Securities" means (i) the Class A Common Stock issued
or issuable at any time to an Initial Investor, including, without limitation,
in connection with the conversion of any Class B Common Stock into Class A
Common Stock or the exercise of any warrant or option to purchase any Class A
Common Stock and (ii) any securities issued or issuable with respect to such
shares of Class A Common Stock in connection with a combination of shares,
recapitalization, merger, consolidation or other reorganization. Registrable
Securities will continue to maintain their status as Registrable Securities in
the hands of any transferee from an Initial Investor provided such transferee
executes a joinder agreement described by Section 9.11. As to any particular
Registrable Securities, such securities will cease to be Registrable Securities
when they have been (x) effectively registered under the Securities Act and
disposed of in accordance with the registration statement covering them or (y)
publicly resold pursuant to Rule 144 (or any similar rule then in force) under
the Securities Act and, in each case, new certificates for them not bearing a
restrictive Securities Act legend have been delivered by the Company and can be
sold without complying with the registration requirements of the Securities Act.

            "Registration Statement" means any Registration Statement of the
Company which covers any of the Registrable Securities pursuant to the
provisions of this Agreement, including the Prospectus, amendments and
supplements to such Registration Statement, including post-effective amendments,
all exhibits and all material incorporated by reference in such Registration
Statement.

            "Required Investors" means, as of the date of any determination
thereof, the holders of Registrable Securities representing an aggregate of not
less than 25% (by number of shares) of all Registrable Securities.

            "Securities Act" means the Securities Act of 1933, as amended, or
any similar Federal statute then in effect, and any reference to a particular
section thereof shall include a reference to a comparable section, if any, of
any such similar Federal statute, and the rules and regulations thereunder.

                                       12
<PAGE>

            8.2 Defined Terms in Corresponding Sections. The following defined
terms, when used in this Agreement, shall have the meaning ascribed to them in
the corresponding Sections of this Agreement listed below:

"Agreement"                                           --    Preamble
"Company"                                             --    Preamble
"Demand Registrations"                                --    Section 1.1
"Holder Indemnitees"                                  --    Section 7.1
"Long-Form Registration"                              --    Section 1.1
"Piggyback Registration"                              --    Section 2.1
"Registration Expenses"                               --    Section 5.1
"Short-Form Registration"                             --    Section 1.1
"Initial Investors"                                   --    Preamble
"Investors"                                           --    Preamble

                                   ARTICLE IX
                                  MISCELLANEOUS

            9.1 Remedies. In the event of a breach by any party to this
Agreement of its obligations under this Agreement, any party injured by such
breach, in addition to being entitled to exercise all rights granted by law,
including recovery of damages, will be entitled to specific performance of its
rights under this Agreement. The parties agree that the provisions of this
Agreement shall be specifically enforceable, it being agreed by the parties that
the remedy at law, including monetary damages, for breach of any such provision
will be inadequate compensation for any loss and that any defense in any action
for specific performance that a remedy at law would be adequate is waived.

            9.2 Amendments and Waivers. Except as otherwise provided herein, no
modification, amendment or waiver of any provision of this Agreement will be
effective against the Company or any holder of Registrable Securities, unless
such modification, amendment or waiver is approved in writing by the Company and
the Investors representing a majority of the Registrable Securities then
outstanding. The failure of any party to enforce any of the provisions of this
Agreement will in no way be construed as a waiver of such provisions and will
not affect the right of such party thereafter to enforce each and every
provision of this Agreement in accordance with its terms.

            9.3 Successors and Assigns. All covenants and agreements in this
Agreement by or on behalf of any of the parties hereto will bind and inure to
the benefit of the respective successors and assigns of the parties hereto
whether so expressed or not.

            9.4 Notices. All notices, requests and other communications
hereunder must be in writing and will be deemed to have been duly given only if
delivered personally against

                                       13
<PAGE>

written receipt or by facsimile transmission or mailed by pre-paid registered or
certified mail, return receipt requested or mailed by overnight courier prepaid
to the parties at the following addresses or facsimile numbers:

            If to the Company, to:

                    eSpeed, Inc.
                    One World Trade Center
                    103rd Floor
                    New York, NY 10023
                    Facsimile No.: (212) 262-1079
                    Attn.: Stephen M. Merkel

                    with a copy to:

                    Morgan, Lewis & Bockius LLP
                    101 Park Avenue
                    New York, New York 10178
                    Facsimile No.: (212) 309-6273
                    Attn.: Christopher T. Jensen

            If to any Investor, to:

                    The last address (or facsimile number) for such Person set
                    forth in the records of the Company.

All such notices, requests and other communications will (i) if delivered
personally to the address as provided in this Section 9.4, be deemed given upon
delivery, (ii) if delivered by facsimile transmission to the facsimile number as
provided in this Section 9.4, be deemed given upon receipt of confirmation,
(iii) if delivered by mail in the manner described above to the address as
provided in this Section 9.4, be deemed given on the earlier of the third full
Business Day following the day of mailing or upon receipt, and (iv) if delivered
by overnight courier to the address provided in this Section 9.4, be deemed
given on the earlier of the first Business Day following the date sent by such
overnight courier or upon receipt. Any party from time to time may change its
address, facsimile number or other information for the purpose of notices to
that party by giving notice specifying such change to the other parties hereto.

            9.5 Headings. The headings used in this Agreement have been inserted
for convenience of reference only and do not define or limit the provisions
hereof.

            9.6 Gender. Whenever the pronouns "he" or "his" are used herein they
shall also be deemed to mean "she" or "hers" or "it" or "its" whenever
applicable. Words in the

                                       14
<PAGE>

singular shall be read and construed as though in the plural and words in the
plural shall be construed as though in the singular in all cases where they
would so apply.

            9.7 Invalid Provisions. If any provision of this Agreement is held
to be illegal, invalid or unenforceable under any present or future law, and if
the rights or obligations of any party hereto under this Agreement will not be
materially and adversely affected thereby, (i) such provision will be fully
severable, (ii) this Agreement will be construed and enforced as if such
illegal, invalid or unenforceable provision had never comprised a part hereof,
(iii) the remaining provisions of this Agreement will remain in full force and
effect and will not be affected by the illegal, invalid or unenforceable
provision or by its severance herefrom and (iv) in lieu of such illegal, invalid
or unenforceable provision, there will be added automatically as a part of this
Agreement a legal, valid and enforceable provision as similar in terms to such
illegal, invalid or unenforceable provision as may be possible.

            9.8 Governing Law. This Agreement shall be governed by and construed
in accordance with the domestic laws of the State of New York; provided,
however, that all provisions of this Agreement within the purview of the General
Corporation Law of the State of Delaware shall be governed by such law.

            9.9 Counterparts. This Agreement may be executed in any number of
counterparts, each of which will be deemed an original, but all of which
together will constitute one and the same instrument.

            9.10 Deferral. Notwithstanding the provisions of Articles I and II,
the Company's obligations to file a Registration Statement, or cause such
Registration Statement to become and remain effective, shall be suspended for a
period not to exceed 90 consecutive days if there exists at the time material
non-public information relating to the Company that, in the reasonable opinion
of the Company's board of directors or counsel, should not be disclosed;
provided further, that the Company may not invoke the foregoing provision more
than two (2) times in any twelve (12) month period.

            9.11 Additional Investors. Any transferee of Registrable Securities
from an Initial Investor shall be entitled to the benefits of this Agreement
upon execution by such transferee of a joinder agreement in form reasonably
satisfactory to the Company stating that such transferee agrees to be bound by
the terms hereof as an "Investor."

                                    ARTICLE X
                               RULE 144 REPORTING

            The Company hereby agrees as follows:

                                       15
<PAGE>

                  (a) The Company shall use commercially reasonable efforts to
make and keep public information available, as those terms are understood and
defined in Rule 144 under the Securities Act, at all times from and after 90
days following the effective date of the first Public Offering.

                  (b) The Company shall use commercially reasonable efforts to
file with the Commission in a timely manner all reports and other documents as
the Commission may prescribe under Section 13(a) or 15(d) of the Exchange Act at
any time after the Company has become subject to such reporting requirements of
the Exchange Act.

                  (c) The Company shall furnish to each holder of Registrable
Securities forthwith upon request (i) a written statement by the Company as to
its compliance with the reporting requirements of Rule 144 (at any time from and
after 90 days following the effective date of the first Public Offering), and of
the Securities Act and the Exchange Act (at any time after it has become subject
to such reporting requirements), (ii) a copy of the most recent annual or
quarterly report of the Company, and (iii) such other reports and documents so
filed as a holder may reasonably request to avail itself of any rule or
regulation of the Commission allowing a holder of Registrable Securities to sell
any such securities without registration.

                                       16
<PAGE>

            IN WITNESS WHEREOF, the parties hereto have executed and delivered
this Agreement as of the date first above written.

                                        COMPANY:

                                        eSPEED, INC.

                                        By: /s/ Douglas B. Gardner
                                            ------------------------------------
                                            Name: Douglas B. Gardner
                                            Title: Vice Chairman

                                        INVESTORS:

                                        CANTOR FITZGERALD SECURITIES

                                        By: /s/ Howard W. Lutnick
                                            ------------------------------------
                                            Name: Howard W. Lutnick
                                            Title: President

                                        CANTOR FITZGERALD, L.P.

                                        By: CF GROUP MANAGEMENT,
                                            INC., its managing partner

                                        By: /s/ Howard W. Lutnick
                                            ------------------------------------
                                            Name: Howard W. Lutnick
                                            Title: President

                [Signature Page to Registration Rights Agreement]<PAGE>

                                    SUBLEASE

      SUBLEASE AGREEMENT dated as of December 15, 1999 between CANTOR FITZGERALD
SECURITIES, a New York general partnership having an office at One World Trade
Center, New York, New York 10048 (hereinafter referred to as "Tenant") and
eSPEED, INC., a Delaware corporation, having an office at One World Trade
Center, New York, New York 10048 (hereinafter referred to as "Subtenant"):

                               W I T N E S S E T H

      WHEREAS, Tenant has leased certain space, more particularly described in
the "Lease" (as hereinafter defined) (the "Demised Premises") located in the
building known as One World Trade Center, New York, New York (the "Building"),
pursuant to the provisions of a lease dated October 12, 1978, as amended (the
"Lease") between The Port Authority of New York and New Jersey ("Landlord") and
Tenant's predecessor-in-interest; and

      WHEREAS, Subtenant is an affiliate of Tenant (with Tenant owning in excess
of 50% of the outstanding shares of Subtenant); and

      WHEREAS, Subtenant, and its wholly owned subsidiaries, have been formed to
provide certain services formerly provided by a division of Tenant in portions
of the Demised Premises; and

      WHEREAS, Subtenant desires to sublease from Tenant such portions of the
Demised Premises consisting of the entire rentable area of the 103rd floor of
the Building (which space is hereinafter called the "Space").

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

      1. Term, Rent, Late Charges.

            a. Tenant hereby sublets the Space to Subtenant, and Subtenant
hereby hires the same from Tenant, for the term (the "Term") commencing on the
date hereof (the "Commencement Date"), and ending on March 15, 2012 (the
"Expiration Date"), subject to the provisions of paragraph 9 hereof (unless
sooner terminated pursuant to the terms hereof).

            b. During the Term, Subtenant shall pay to Tenant, on the first day
of each calendar month, an amount equal to the product obtained by multiplying
(x) the rate per rentable square foot then being paid by Tenant for rent and all
items of additional rent with respect to the Space pursuant to the Lease, by (y)
the number of rentable square feet constituting the Space, which, for all
purposes, the parties agree is 50,395. Subtenant agrees to pay such rent as
provided herein, without any set-off or deduction whatsoever, except as
otherwise expressly provided herein. To the extent that Tenant shall be entitled
to an abatement of rent and/or additional rent accruing under the Lease during
the Term, and arising from a condition which, if Subtenant were the tenant under
the Lease, and assuming the Space were the only space demised hereunder, would
have entitled Subtenant to such an abatement, then Subtenant shall be entitled
to an abatement of rent and/or additional rent hereunder to the extent of the
lesser of (x) the amount of the abatement to which Tenant is entitled, or (y)
the rent and additional rent payable by Subtenant hereunder during the period of
such abatement. Payments for any partial calendar month shall be prorated on a
per diem basis.

      2. Use. Subtenant shall use and occupy the Space only as offices and
trading facilities, for providing to institutional and retail broker-dealer,
other financial services firms and other sellers of goods or services direct,
electronic access to certain proprietary hardware, software, trading
technologies and systems designed to enable such firms to electronically match,
execute and settle trades in a wide variety of fixed income, futures products
and other products, subject, in any event, to the provisions of the Lease.
Subtenant acknowledges that the Space may be used only for uses which the
Landlord determines, acting in a non-arbitrary and non-capricious manner, are in
accordance with Chapter 5 of Title 17 of the Unconsolidated Laws of the State of
New York.
<PAGE>

      3. Incorporation of the Lease, Quiet Enjoyment. This Sublease is expressly
made subject and subordinate to the terms and conditions of the Lease and to any
and all mortgages and/or ground leases to which the Lease may be or become
subject and subordinate. Subtenant hereby agrees to perform all obligations of
Tenant under the Lease and to comply with and abide by the terms and conditions
thereof, insofar as the same relate to the Space and to Subtenant's use and
occupancy thereof arising and accruing during the Term, except for the payment
of Tenant's rent and additional rent owing thereunder, other than as set forth
in paragraph 1.b hereof. Tenant agrees that Subtenant, upon paying all rent and
other charges to be paid by it hereunder, and observing the covenants and
conditions hereof on its part to be performed, shall peaceably and quietly enjoy
the Space, subject, nevertheless, to the terms and conditions of the Lease.
Subtenant shall be entitled to and shall receive, and Tenant shall cooperate
with Subtenant at its request in securing for Subtenant, all of the rights,
privileges, elections, benefits and services available to Tenant under the
Lease, insofar as the same relate to the Space and Subtenant's use and occupancy
thereof, except that Subtenant shall not be entitled to any portion of the
construction contribution provided for under the Lease with respect to the
Space. However, Tenant will not be liable to Subtenant for any failure of
Landlord in providing such rights, privileges, elections, benefits and services.

      4. Assignment and Subletting. Subtenant will not assign this Sublease or
allow the same to be transferred by operation of law or otherwise, and will not
further sublet the Space or any part thereof, or allow the Space, or any part
thereof, to be used by others, except with the prior written consent of Tenant
and Landlord in accordance with the provisions of the Lease. Any attempted
assignment or subletting which is contrary to the provisions of this paragraph
shall be void. Notwithstanding the foregoing, Tenant acknowledges that portions
of the Space shall be used by eSpeed Securities, Inc., eSpeed Markets, Inc. and
eSpeed Government Securities, Inc. for the uses contemplated by, and subject to
the provisions of, paragraph 2 hereof. Subtenant represents and warrants to
Tenant that each of such entities is a wholly owned subsidiary of Subtenant. In
reliance upon such representation, Tenant hereby approves such use, so long as
such entities shall remain wholly owned subsidiaries of Subtenant.

      5. Alterations. Subtenant has examined the Space and agrees to accept the
Space in its existing condition and state of repair. Any alterations or
remodeling that Subtenant may desire to effect shall be subject to the prior
written consent of Tenant and Landlord in accordance with the provisions of the
Lease, and shall be at the sole expense of Subtenant.

      6. Fixtures and Installations. All alterations, decorations, installations
and improvements made in the Space, including all paneling, partitioning and the
like, made by either Tenant or Subtenant, shall become the property of Tenant
and shall remain upon and be surrendered with the Space as part thereof at the
end of the term hereof. Trade fixtures, furnishings, decorations which are not
an integral part of the Space and all items of Subtenant's personal property
(collectively, "Subtenant's Property"), shall remain the property of Subtenant,
and shall be removed from the Space by and at the expense of Subtenant prior to
the expiration or other termination of the Term. Any repairs that may be
necessitated by the removal of Subtenant's Property shall be promptly made by
and at the expense of Subtenant.

      7. Signs. Tenant shall cooperate with Subtenant with respect to requesting
that Landlord place Subtenant's name in any building directory serving the
Building. Any expense incurred with respect to such request or listing shall be
paid by Subtenant. No signs may be put on or in any window nor on the exterior
of the Building. Any signs or lettering in the public corridors or on the doors
must be submitted to Tenant and Landlord for approval before installation.
Tenant agrees that so long as Landlord shall approve such installation, Tenant
shall not unreasonably withhold or delay its consent to same.

      8. End of Term, Holdover.

            a. Upon the expiration or other termination of the Term, Subtenant
shall quit and surrender to Tenant the Space, broom clean, in good order and
condition, ordinary wear and tear and damage by casualty excepted, and otherwise
in the condition required under the Lease, and Subtenant shall remove all of
Subtenant's Property, and shall repair all damage to the Building occasioned by
such removal. Any property not removed from

                                       2
<PAGE>

the Space shall be deemed abandoned by Subtenant and may be disposed of in any
manner deemed appropriate by the Tenant.

            b. In no event shall Subtenant have any right to remain in
possession of any part of the Space after the expiration or other termination of
this Sublease, and Subtenant agrees and understands that (i) it is affirmatively
obligated to surrender possession of the Space to Tenant on or before the
expiration or other termination of this Sublease, and (ii) any such continued
occupation of the Space beyond such date may cause Tenant to sustain
consequential damages. Subtenant shall be subject not only to summary
proceedings, but also to all costs, losses and damages (consequential or
otherwise) related thereto, including, without limitation, any damages arising
out of any lost opportunities (and/or new subleases) by Tenant to re-let the
Space or any part thereof, in addition to any other remedy provided in this
Sublease (as if the same had not expired or terminated) or at law. All damages
to Tenant by reason of such holding over by Subtenant may be the subject of a
separate action and need not be asserted by Tenant in any summary proceedings
against Subtenant.

            c. The aforesaid provisions of this paragraph 8 shall survive the
expiration or sooner termination of this Sublease.

      9. Early Termination. Tenant and Subtenant acknowledge and agree that the
parties intend that the Term of this Sublease shall end one (1) day prior to the
term of the Lease, which day is set forth as the Expiration Date in paragraph
1.a hereof. Subtenant further acknowledges that Tenant has an option (the "Early
Termination Option"), as set forth in the Lease, to cancel the Lease prior to
the expiration date thereof (which date may be earlier than the Expiration Date
hereunder). Anything contained herein to the contrary notwithstanding
(including, without limitation, the provisions of paragraphs 1.a and 15.f
hereof), Subtenant agrees that in the event Tenant shall exercise its Early
Termination Option under the Lease, and as a result thereof, the Lease shall
terminate prior to the Expiration Date hereunder, then the Expiration Date
hereunder shall be one (1) day prior to the date on which the Lease shall
terminate, and this Sublease shall terminate and expire on such date with the
same force and effect as if such date were the Expiration Date originally
provided for herein. Tenant shall send Subtenant a copy of Tenant's notice
exercising the Early Termination Option simultaneously with Tenant sending such
notice to the Landlord. Subtenant further agrees that Tenant shall have no
liability to Subtenant by reason of Tenant's exercise of the Early Termination
Option and the early termination of this Sublease as a result thereof.

      10. Choice of Laws, Jurisdiction. This Sublease shall be construed in
accordance with the laws of the State of New York. Each party hereby consents to
the jurisdiction and venue of the courts of the State of New York and the United
States District Court for the Southern District of New York in connection with
any claim or controversy arising out of or relating to this Agreement.

      11. Indemnity, Insurance.

            a. Unless caused by Tenant's negligent acts, or the negligent acts
of Tenant's employees, agents, representatives and contractors, Tenant shall not
be liable for any damage to persons or property sustained by Subtenant and
others by reason of Subtenant's use and occupancy of the Space. Subtenant agrees
to indemnify and save Tenant harmless from and against any and all claims
arising from Subtenant's use and occupancy of the Space, and will carry
liability insurance for bodily injury, death and property damage having limits
in the amount of $3,000,000 combined single limit, naming Tenant and Landlord as
additional insureds. At or before the Commencement Date, Subtenant will furnish
Tenant with a certificate evidencing such insurance coverage for the benefit of
Subtenant, Tenant and Landlord, as their respective interests may appear.

            b. Neither Tenant nor its agents shall be liable for any damage to
property of Subtenant or of others entrusted to employees of the Building or of
Tenant, nor for the loss of or damage to any property of Subtenant by theft or
otherwise. Neither Tenant nor its agents shall be liable for any injury or
damage to persons, property or business resulting from fire, explosion, falling
plaster, steam, gas, electricity, electrical disturbance,

                                       3
<PAGE>

water, rain or snow or leaks from any part of the Building or from the pipes,
appliances or plumbing works or from the roof, street or subsurface or from any
other place or by dampness or by any other cause of whatsoever nature, unless
caused by or due to the negligence of Tenant, its agents, servants,
representatives, contractors or employees; nor shall Tenant or its agents be
liable for any such damage caused by Landlord, other tenants or persons in the
Building or caused by operations in construction of any private, public or quasi
public work; nor shall Tenant be liable for any latent defect in the Space or in
the Building. Subtenant shall reimburse and compensate Tenant as additional rent
for all expenditures made by, or damages or fines sustained or incurred by
Tenant due to, non- performance or non-compliance with or breach or failure to
observe any term, covenant or condition of this Sublease upon Subtenant's part
to be kept, observed, performed or complied with. Subtenant shall give immediate
notice to Tenant in case of fire or accidents in the Space or in the Building or
of defects therein or in any fixtures or equipment. Each party shall give the
other party copies of any notices received from Landlord with respect to the
Space during the Term, promptly upon such party's receipt of such notices.

      12. Casualty/Condemnation. With respect to the Space, Subtenant shall have
the same rights and obligations as Tenant under the Lease, as if the Space were
the only space demised to Tenant thereunder, in the case of damage to or
destruction of the Space by fire or other causes or in the case of condemnation.

      13. Default. Any material violation by Subtenant of any of the terms,
provisions, covenants or conditions of the Lease, or of any rules or regulations
promulgated and enforced by Landlord, which violation continues beyond any
applicable grace or notice period provided for the cure thereof, shall
constitute a violation of this Sublease. In the event of any such violation or
of any default in the payment of rent or any other material violation of this
Sublease, Tenant, after giving Subtenant ten (10) days' prior written notice of
any payment default and twenty (20) days' written notice for nonpayment
defaults, shall have and may exercise against Subtenant all the rights and
remedies available to the Landlord under the Lease, as though the same were
expressly reiterated herein as the rights of Tenant, unless within the
applicable cure period Subtenant has cured the specified default or violation or
if the specified default or violation is of such a nature that it cannot be
cured within said period, Subtenant has commenced the curing thereof within said
period, and diligently prosecutes such curing to completion. No waiver of any
such violation by either Tenant or its Landlord shall be deemed a waiver of the
term, provisions, covenant, condition, rule or regulation in question or any
other subsequent violation.

      14. Notices. All payments and notices made or given hereunder shall be
deemed sufficiently made or given if sent by registered or certified mail,
return receipt requested, or by recognized overnight courier as follows:

To Tenant:                              Cantor Fitzgerald Securities
                                        One World Trade Center
                                        New York, NY 10048
                                        Attn: Douglas B. Gardner

To Subtenant:                           eSpeed, Inc.
                                        One World Trade Center
                                        103rd Floor
                                        New York, NY 10048
                                        Attn: General Counsel

or to such other address as may be specified by either party hereto by written
notice to the other party hereto.

      15. Miscellaneous.

            a. The term "Tenant" as used in this Sublease means only the person
to whom Subtenant is required by law to attorn, so that, for example, in the
event of any assignment by Tenant of the Lease, Tenant shall be and hereby is
freed and relieved of all terms, covenants, conditions, provisions and agreement
of the Tenant

                                       4
<PAGE>

thereafter accruing and it shall be deemed and construed, without further
agreement between the parties hereto, or their successors and interests, or
between the parties hereto and the Assignee, that the Assignee has assumed and
agreed to carry out any and all covenants and obligations of Tenant thereafter
accruing hereunder.

            b. Subtenant shall look solely to the estate and property of Tenant
in the Lease for the satisfaction of Subtenant's remedies for the collection of
a judgment (or other judicial process) requiring the payment of money by Tenant
in the event of any default or breach by Tenant with respect to any of the
terms, covenants and/or conditions of this Sublease to be observed and/or
performed by Tenant, and no other property or assets of such Tenant shall be
subject to levy, execution or other enforcement procedure for the satisfaction
of Subtenant's remedies.

            c. With respect to any provision of this Sublease which provides for
Tenant's approval and/or consent, Subtenant, in no event, shall be entitled to
make, nor shall Subtenant make any claim, and Subtenant hereby waives any claim,
for money damages, nor shall Subtenant claim any money damages by way of
set-off, counterclaim or defense, based upon any claim or assertion by Subtenant
that Tenant has unreasonably withheld or unreasonably delayed any such consent
or approval.

            d. Any obligation of Tenant which is contained in this Sublease may
be observed or performed by Tenant using reasonable efforts to cause the
Landlord under the Lease to observe and/or perform the same. In the event of a
default by Landlord in the observance and/or performance of any of its
obligations under the Lease relating to the Space, or the use thereof by
Subtenant, Tenant agrees that it shall, upon notice from Subtenant, make demand
upon Landlord to perform its obligations under the Lease and, provided that
Subtenant specifically agrees to pay its pro-rata share (based on the ratio of
the affected area of the Space to the affected area of the entire Demised
Premises), of all costs and expenses of Tenant, Tenant shall take all
appropriate action (including commencement and prosecution of appropriate legal
proceedings, provided Subtenant agrees to indemnify [on a pro-rata basis, as
provided above] Tenant for any loss, damages, costs and expenses, including
reasonable attorneys' fees and disbursements, that Tenant may incur as a result
of commencing such legal proceedings) to enforce the Lease. Tenant shall pay the
rent and additional rent due under the Lease, and perform all other covenants of
Tenant thereunder.

            e. Tenant shall promptly deliver to Subtenant all written notices of
default, and notices relating in any material way to the Space, that Tenant
receives from Landlord under the Lease.

            f. Tenant hereby represents, warrants and covenants to Subtenant
that: (i) Tenant has provided Subtenant with a true, correct and complete copy
of the Lease, as amended, and the Lease represents the entire agreement between
Tenant and Landlord with respect to the Lease of the Demised Premises, (ii) the
Lease is in full force and effect, (iii) neither Landlord nor Tenant has
exercised any option or right to (x) cancel or terminate the Lease or shorten
the term thereof or (y) reduce or relocate the Demised Premises (except as set
forth in the Lease), (iv) the expiration date of the Lease is March 16, 2012,
and (v) Tenant agrees that it shall not amend, terminate, modify, waive,
surrender the Lease, without the prior written consent of Subtenant (except as
contemplated in paragraph 9 hereof), if such amendment, termination,
modification, waiver or surrender shall adversely affect Subtenant's rights and
privileges under this Sublease.

      16. Broker. Tenant and Subtenant each, as indemnitor, warrants and
represents to the other, as indemnitee, that insofar as indemnitor knows, no
brokers negotiated this Sublease or are entitled to a commission in connection
therewith. Indemnitor does hereby agree to indemnify, defend and hold
indemnitee, harmless of and from any claim, damages, judgment, cost and/or
expense (including, without limitation, reasonable attorneys' fees and
disbursements) incurred by the indemnitee by reason of any claim of any broker,
person or entity who claims to have dealt with the indemnitor in connection with
the Space or this Agreement.

      17. Landlord's Consent. Simultaneously with the execution hereof, Tenant
and Subtenant are executing a Consent to Sublease Agreement substantially in the
form annexed hereto as Exhibit 1, which, pursuant to

                                       5
<PAGE>

the terms of the Lease, is a condition to obtaining the consent of the Landlord
to this Sublease. Tenant shall promptly deliver such Consent to Sublease
Agreement to Landlord for its signature, and shall deliver a fully executed copy
thereof to Subtenant promptly upon receipt by Tenant of same from Landlord.
Subtenant acknowledges that pursuant to the terms of the Lease, Landlord is
required to grant its consent to this Sublease by reason of the fact that
Subtenant is and maintains a relationship with Tenant, as more fully described
in paragraph 2 of that certain Supplemental No. 2 to the Lease. Subtenant
further acknowledges that if at any time during the Term, such required
relationship is no longer in effect, the Landlord shall have the right, inter
alia, to revoke its consent to this Sublease, in which event this Sublease shall
immediately terminate and expire and Subtenant shall immediately vacate the
Space and surrender same to Tenant. Subtenant agrees that Tenant shall have no
liability to Subtenant for any damages, losses, liability or expense in the
event of any such termination.

      18. Entire Agreement. Except only as to references to the Lease contained
herein, this Agreement contains the entire agreement of the parties relating to
the subject matter hereof and supersedes all prior negotiations, conversations,
correspondence and agreements. There are no representations or warranties not
set forth herein. No waiver or modification hereof shall be valid or effective
unless in writing signed by the party or parties thereby affected.

      19. Successors and Assigns. This Sublease shall bind and inure to the
benefit of the parties hereto and their successors and assigns.

                            [Signature Page Follows]

                                       6
<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Sublease to be
duly executed as of the day and year first above written.

                        TENANT:         Cantor Fitzgerald Securities

                                        By: /s/ Howard W. Lutnick
                                            ------------------------------------
                                            Name: Howard W. Lutnick
                                            Title: President

                        SUBTENANT:      eSpeed, Inc.

                                        By: /s/ Douglas B. Gardner
                                            ------------------------------------
                                            Name: Douglas B. Gardner
                                            Title: Vice Chairman

                      [Signature Page to New York Sublease]

                                       7

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