Document:

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                          REGISTRATION RIGHTS AGREEMENT

                                  by and among

                                  eSpeed, Inc.

                                       and

                           The Investors Named Herein

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                                TABLE OF CONTENTS
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<S>                                                                                                              <C>
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    Selection of Underwriter ...............................................................................3
ARTICLE II PIGGYBACK REGISTRATIONS ...............................................................................3
   2.1    Right to Piggyback .....................................................................................3
   2.2    Piggyback Expenses .....................................................................................4
   2.3    Priority on Primary Registrations ......................................................................4
   2.4    Priority on Secondary Registrations ....................................................................4
ARTICLE III HOLDBACK AGREEMENTS ..................................................................................5
ARTICLE IV REGISTRATION PROCEDURES ...............................................................................5
ARTICLE V REGISTRATION EXPENSES ..................................................................................8
   5.1    Registration Expenses ..................................................................................8
   5.2    Holders' Expenses ......................................................................................8
ARTICLE VI UNDERWRITTEN AND OTHER OFFERINGS ......................................................................8
   6.1    Underwriting Agreement .................................................................................8
   6.2    Obligations of Participants ............................................................................8
ARTICLE VII INDEMNIFICATION ......................................................................................9
   7.1    Company's Indemnification Obligations ..................................................................9
   7.2    Holder's Indemnification Obligations ..................................................................10
   7.3    Notices; Defense; Settlement ..........................................................................10
   7.4    Indemnity Provision ...................................................................................11
ARTICLE VIII DEFINITIONS ........................................................................................11
   8.1    Terms .................................................................................................11
   8.2    Defined Terms in Corresponding Sections ...............................................................13
ARTICLE IX MISCELLANEOUS ........................................................................................14
   9.1    Amendments and Waivers ................................................................................14
   9.2    Successors and Assigns ................................................................................14
   9.3    Notices ...............................................................................................14
   9.4    Headings ..............................................................................................15
   9.5    Gender ................................................................................................15
   9.6    Invalid Provisions ....................................................................................15
   9.7    Governing Law; Forum; Process .........................................................................15
   9.8    Counterparts ..........................................................................................16
   9.9    Additional Investors ..................................................................................16
ARTICLE X RULE 144 REPORTING ....................................................................................16
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                  REGISTRATION RIGHTS AGREEMENT (the "Agreement"), dated as of
June 5, 2000, by and among eSpeed, Inc., a Delaware corporation (the "Company"),
the parties that have executed the signature pages hereto (the "Initial
Investors") and such other parties that otherwise execute a joinder agreement
and become a party hereto (collectively, the "Investors").

                                    RECITALS

                  WHEREAS, as an inducement to each of the Initial Investors to
invest in the Company, the Company desires to grant to each of the Initial
Investors registration rights with respect to the shares (the "Shares") of Class
A Common Stock (as defined in Section 8.1 below) and warrants to purchase shares
of Class A Common Stock (the "Warrants") issued to the Initial Investors on the
date hereof as set forth on Schedule A hereto, on the terms and subject to the
conditions set forth herein.

                  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 Initial Investors may request, in writing, registration
under the Securities Act of all or part of their Registrable Securities. Within
15 days after receipt of any such request, the Company will give notice of such
request to all other Investors and to other persons holding piggyback
registration rights entitling them to have securities of the Company included
within such registration ("Other Holders"). Thereafter, the Company will use all
reasonable efforts to effect the registration under the Securities Act (i) on
Form S1 or any similar long-form registration statement (a "Long-Form
Registration") or (ii) on Form S3 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 and securities of the Company held by the Other Holders with respect
to which the Company has received written requests for inclusion therein within
20 days after the receipt of the Company's notice, subject to the provisions of
Section 1.4. All registrations initiated by an Investor pursuant to this Section
1.1 are referred to herein as "Demand Registrations". The Company shall not be
required to effect any underwritten Demand Registration requested by an Initial
Investor if either (a) within the 12 months preceding the receipt by the Company
of such request, the Company has filed and has had declared effective by the
Commission a Registration Statement with respect to an underwritten offering
under this Section 1.1 or has filed and has had declared effective by the
Commission another Registration Statement with respect to an underwritten
offering to which the Piggyback Registration rights set forth in Article II
hereof apply and such Initial Investor had an opportunity to include all the
shares requested to be included in such Registration Statements; and provided
further that the Company shall not be required to effect any Demand Registration
requested by an Initial Investor if such Investor may sell all of the

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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. The rights of an Initial Investor pursuant to this
Section 1.1 shall be assignable in accordance with the provisions of Section
9.9.

                  1.2.  Number of Demand Registrations; Expenses . Subject to
Sections 1.1 and 1.3 hereof, each of the Initial Investors shall be entitled to
(i), from and after the one year anniversary of the date hereof, one Demand
Registration and (ii), from and after the date on which such Initial Investor's
Warrants become fully exercisable, one additional Demand Registration, with no
more than one 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
$20,000,000. The Company will pay all Registration Expenses in connection with
any Demand Registration.

                  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 45 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. The Initial Investors of the Registrable Securities
shall be permitted to withdraw all or any part of the Registrable Securities
from a Demand Registration at any time prior to the effective date of such
Demand Registration; provided that in the event of, and concurrently with such
withdrawal, the Initial Investors responsible for such Demand Registration shall
either (x) pay or reimburse the Company for all fees and expenses (including
counsel fees and expenses) incurred by them and the Company prior to such
withdrawal or (y) agree to forfeit one of its Demand Registration rights
hereunder.

                  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 include in such registration (i) first, the number of Registrable
Securities requested to be included which, in the opinion of such underwriters,
can be sold, by the Investor initiating the Demand Registration, (ii) second,
that number of other shares of Common Stock proposed to be included in such
registration equally between Cantor Fitzgerald Securities and its Affiliates,
and their successors and assigns on the one hand (the "Priority Piggyback
Registration Holders"), and any other Investors exercising their Piggyback
Registration rights on the one

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hand and (iii) third, that number of other shares of Common Stock proposed to be
included in such registration, pro rata among any other holders exercising their
respective piggyback registration rights thereof based upon the total number of
shares which such holders propose to include in such registration.

                  1.5.  Selection of Underwriter. If the Investor exercising
its right to a Demand Registration so elects, the offering of such Registrable
Securities pursuant to such Demand Registration shall be in the form of an
underwritten offering. The Company shall select one or more nationally
recognized firms of investment bankers to act as the lead managing Underwriter
or Underwriters in connection with such offering and shall select any additional
investment bankers and managers to be used in connection with the offering.

                  1.6.  Limitations, Conditions and Qualifications to
Obligations for a Demand Registration. The Company shall be entitled to
postpone, for a reasonable period of time (but not exceeding 90 days), the
filing of any registration statement otherwise required to be prepared and filed
by it pursuant to Section 1.1 if the Company determines, in its good faith
judgment, that such registration and offering would interfere with any material
financing, acquisition, corporate reorganization or other material transaction
involving the Company or any of its Affiliates and promptly gives the holders of
Registrable Securities requesting registration thereof pursuant to Section 1.1
written notice of such determination, containing an approximation of the
anticipated delay. If the Company shall so postpone the filing of a registration
statement, holders of Registrable Securities requesting the Demand Registration
pursuant to Section 1.1 shall have the right to withdraw the request for
registration by giving written notice to the Company within 30 days after
receipt of the notice of postponement and, in the event of such withdrawal, such
request shall not be counted for purposes of the requests for registration to
which holders of Registrable Securities are entitled pursuant to Section 1.1
hereof.

                                   ARTICLE II
                            PIGGYBACK REGISTRATIONS

                  2.1.  Right to Piggyback . From and after the date which is
12 months from the date of this Agreement, whenever the Company proposes to
register any of its equity securities under the Securities Act (other than a
registration effected in connection with a Company stock option or other
employee benefit plan (such as a Registration Statement on Form S8), a
registration effected in connection with the conversion of debt securities, a
registration on any form that does not include substantially the same
information as would be required to be included in a registration statement
covering the sale of Registrable Securities (such as a Registration Statement on
Form S4), or a registration effected in connection with an acquisition), and
the form of registration statement to be used may be used for the registration
of Registrable Securities (a "Piggyback Registration"), the Company will give
notice (the "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, subject to the provisions of Section 2.3 and 2.4 hereof. Such requests
for inclusion shall be in writing and delivered to the Company within 20 days
after the Investor's receipt of the Notice and shall specify the number of
Registrable Securities intended to be

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disposed of and the intended method of distribution thereof. Any holder shall
have the right to withdraw its request for inclusion of its Registrable
Securities in any Registration Statement pursuant to this Section 2.1 by giving
written notice to the Company of its request to withdraw. The Company may
withdraw a Piggyback Registration at any time prior to the time it becomes
effective. The Company is not required to include in a registration any
Registrable Securities which the holder is not then entitled to offer to sell
whether by contractual restriction or by law.

                  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 other shares of Common Stock proposed to be included in
such registration by the Priority Piggyback Registration Holders and (iii)
third, that number of other shares of Common Stock proposed to be included in
such registration, pro rata among any other holders (including the Investors)
exercising their respective piggyback registration rights thereof based upon the
total number of shares which such holders (including the Investors) propose to
include in such registration.

                  2.4.  Priority on Secondary Registrations . If a Piggyback
Registration 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 the holders
exercising their demand registration rights, and (ii) second, that number of
other shares of Common Stock proposed to be included in such registration, pro
rata among any other holders (including the Investors) exercising their
respective piggyback registration rights thereof based upon the total number of
shares which such holders (including the Investors) propose to include in such
registration.

                                   ARTICLE III
                               HOLDBACK AGREEMENTS

                  In the event the Company or another holder of the Company's
stock proposes to enter into an underwritten public offering, each holder of
Registrable Securities agrees to enter into an agreement with the managing
underwriters not to effect any sale or distribution of equity securities of the
Company, or any securities convertible, exchangeable or exercisable for or into
such securities, during the period beginning on the date of such offering and
extending for up to 90 days; provided that such holders shall not be so
obligated unless the Company and each of its Affiliates enter into the same or
comparable lockup agreement for the same period and further shall not be so
obligated if such holder then owns less than 2% of the outstanding Class A
Common Stock.

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                                   ARTICLE IV
                            REGISTRATION PROCEDURES

                  Whenever holders of Registrable Securities have requested that
any Registrable Securities be registered pursuant to this Agreement (the
"Selling Holders"), 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 and, pursuant thereto, the Company will:

                  (a).  use reasonable efforts to prepare and file with the
Commission a Registration Statement with respect to such Registrable Securities
as soon as practicably thereafter and, in the case of a Demand Registration
within 60 days (subject to a postponement pursuant to Section 1.6) of the
request for a Demand Registration 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 the Selling Holders copies
of all such documents proposed to be filed and (ii) notify each Selling 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; and provided further that
the Company shall not be required to keep such Registration Statement effective
for more than (i) 45 days in the case of a Piggyback Registration or a Demand
Registration with respect to an underwritten offering or (ii) 180 days in the
case of a Demand Registration (or such shorter period which will terminate when
all Registrable Securities covered by such Registration Statement have been
sold, but not prior to the expiration of the applicable period referred to in
Section 4(3) of the Securities Act and Rule 174 thereunder, if applicable);

                  (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 for as long as such registration is required to remain
effective pursuant to the terms hereof 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;

                  (c).  furnish to each Selling Holder, 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 such other documents as such seller
may reasonably request in order to facilitate the disposition of the Registrable
Securities owned by such Selling Holder;

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                  (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 in which a registration or qualification
is required as any Selling Holder 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 Selling Holder to consummate
the disposition in such jurisdictions of the Registrable Securities owned by
such Selling Holder; 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).  notify each Selling Holder, 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 Selling Holder, the Company will prepare and furnish such Selling
Holder 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;

                  (f).  make available for inspection by any Selling Holder,
any underwriter participating in any disposition pursuant to such Registration
Statement and any attorney, accountant or other agent retained by any such
Selling Holder or underwriter, all applicable, nonconfidential due diligence
documents of the Company which are requested, 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, including a
customary accountant's "comfort" letter and opinion of counsel to the Company;

                  (g).  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 selfregulatory organizations as may be
necessary to enable the Selling Holders thereof to consummate the disposition of
such Registrable Securities;

                  (h).  promptly notify the Selling Holders 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

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any Registration Statement or of any order preventing or suspending the use of
any preliminary Prospectus; and

                  (i).  promptly notify the Selling Holders of the occurrence
of any pending material merger, acquisition, corporate reorganization or other
material transaction involving the Company or any of its Affiliates which makes
it imprudent for the Company to be in registration, as determined in the good
faith judgment of the Company (a "Black-Out Period"). The Company shall not
impose BlackOut Periods that, either individually or in the aggregate, exceed
90 days during any fiscal year of the Company.

                  The Company may require each Selling Holder to promptly
furnish in writing to the Company such information regarding the distribution of
the Registrable Securities as the Company may from time to time reasonably
request and such other information as may be legally required in connection with
such registration including, without limitation, all such information as may be
requested by the Commission or any regulatory authority. The Company may exclude
from such Registration Statement any holder who fails to provide such
information.

                  Each Selling Holder agrees that, upon receipt of any notice
from the Company of the happening of any event of the kind described in
paragraph (a), (e), (h) or (i) above, such Selling Holder will forthwith
discontinue disposition of Registrable Securities pursuant to the Registration
Statement covering such Registrable Securities until such Selling Holder's
receipt of the copies of the supplemented or amended prospectus contemplated by
paragraph (a) or (e) above, or in the case of a BlackOut Period until the
Company notifies the Selling Holders that the period has ended, and, if so
directed by the Company, such Selling Holder will deliver to the Company all
copies, other than permanent file copies then in such Selling Holder's
possession, of the most recent prospectus covering such Registrable Securities
at the time of receipt of such notice. The periods referred to in paragraph (a)
above for maintaining the effectiveness of the Registration Statement shall be
extended for a period equal to the period during which the disposition of the
Registrable Securities is discontinued as set forth in the immediately preceding
sentence.

                                    ARTICLE V
                             REGISTRATION EXPENSES

                  5.1.  Registration Expenses . All registration and filing
fees, fees and expenses of compliance with securities or "blue sky" laws,
printing expenses, listing fees for securities to be registered on a national
securities exchange or The Nasdaq Stock Market and all independent certified
public accountants, underwriters (excluding discounts and commissions), fees and
expenses of counsel to the Company and other Persons retained by the Company
(all such expenses being herein called "Registration Expenses") will be borne by
the Company as provided in Sections 1.2 and 2.2 of this Agreement, but subject
to the provisions of Section 1.3 of this Agreement.

                  5.2.  Holders' Expenses . The Company shall have no
obligation to pay (i) any underwriting discounts or commissions attributable to
the sale, or potential sale, of Registrable

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Securities, which expenses will be borne by all Selling Holders of Registrable
Securities included in such registration; and (ii) any fees or expenses of
counsel or others retained by the Selling Holders in connection with the sale,
or potential sale, of Registrable Securities.

                                   ARTICLE VI
                        UNDERWRITTEN AND OTHER OFFERINGS

                  6.1.  Underwriting Agreement . If requested by the
underwriters for any underwritten offering involving the Registrable Securities,
the Company will enter into an underwriting agreement with such underwriters for
such offering, such agreement to be reasonably satisfactory to the Company and
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 . 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. In addition, the Company may
require each Selling Holder to promptly furnish in writing to the Company such
information regarding the distribution of the Registrable Securities as the
Company may from time to time reasonably request and such other information as
may be legally required in connection with such registration including, without
limitation, all such information as may be requested by the Commission or the
NASD. The Company may exclude from such Registration Statement any Holder who
fails to provide such information.

                                   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 reasonable expense arising out of or based upon an untrue statement or
alleged untrue statement of a material 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

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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 reasonable 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 prior written consent of the Company;
and

                   (iii) against any and all reasonable 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); provided further, that (other than in
connection with an underwritten offering) 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; 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 to the
extent that any such loss, liability, claim or expense arises out of or is based
upon an untrue statement or omission in any Prospectus, even if an amended and
corrected Prospectus is not furnished to such holder, but only to the extent
that the holder, after being notified by the Company pursuant to paragraph (e)
of Article III hereof, continues to use such Prospectus and in such case and to
the extent of, and with respect to, damages which arise after the holder
receives such notice.

                  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 such Registration Statement, any preliminary, final or summary
Prospectus contained therein, or

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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 expressly for inclusion in such Registration Statement. 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 received by such holder (after deducting any
underwriting discount) 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 the reasonable opinion of counsel to such indemnified
party 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 the
Selling Holders, selected by a majority of the Selling Holders or (ii) more than
one counsel for the Company in connection with any one action or separate but
similar or related actions, as applicable. 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 opinion of counsel to 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 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.

                                       10
<PAGE>

                  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.

                                  ARTICLE VIII
                                  DEFINITIONS

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

         "Affiliate" means, with respect to any specified party, any other
individual, partnership, corporation or other organization, whether incorporated
or unincorporated, who, directly or indirectly through one or more
intermediaries, controls, or is controlled by, or is under common control with,
such specified party. The term "control" means the possession, directly or
indirectly, of the power to direct or cause the direction of the management and
policies of a party, whether through the ownership of voting securities, by
contract or otherwise; and the terms "controlling" and "controlled" have
meanings correlative of the foregoing.

         "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.

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

         "Common Stock" means the shares of Common Stock, regardless of
designation, of the Company.

         "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.

         "NASD" means the National Association of Securities Dealers, Inc.

         "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.

         "Prospectus" means the Prospectus included in any Registration
Statement (including without limitation, a Prospectus that disclosed information
previously omitted from a Prospectus

                                       11
<PAGE>

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 posteffective
amendments, and all material incorporated by reference or deemed to be
incorporated by reference in such Prospectus.

         "Registrable Securities" means (i) the Shares, (ii) the Class A Common
Stock issued or issuable at any time upon the exercise of the Warrants, and
(iii) any securities issued or received in respect of, or in exchange or in
substitution for any of the foregoing. Registrable Securities will continue to
maintain their status as Registrable Securities in the hands of a transferee
from an Investor of a majority of the Registrable Securities held by such
Investor provided such transferee executes a joinder agreement described by
Section 9.9. After the transfer (in one or more transactions) of a majority of
the Registrable Securities held by an Investor, any remaining Registrable
Securities held by such Investor shall cease to be Registrable Securities. As to
any particular Registrable Securities, such securities will cease to be
Registrable Securities when they (w) have been effectively registered under the
Securities Act and disposed of in accordance with the registration statement
covering them, (x) may be sold pursuant to Rule 144 under the Securities Act
without volume or manner of sale limitation (or any similar provisions then in
force), (y) have been otherwise transferred and the Company has delivered a new
certificate or other evidence of ownership for such securities not bearing a
restrictive legend and not subject to any stop order and such securities may be
publicly resold by the Person receiving such certificate without complying with
the registration requirements of the Securities Act, or (z) have ceased to be
outstanding.

         "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 posteffective amendments,
all exhibits and all material incorporated by reference in such Registration
Statement.

         "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.

                  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 Registration"      --                             Section 1.1
"Holder Indemnitees"--                                    Section 7.1

                                       12
<PAGE>

"Initial Investors"     --                                Preamble
"Investors" --                                            Preamble
"LongForm Registration" --                                Section 1.1
"Notice"    --                                            Section 2.1
"Other Holders"  --                                       Section 1.1
"Piggyback Registration"  --                              Section 2.1
"Priority Piggyback Registration Holders"                 Section 1.4
"Registration Expenses"  --                               Section 5.1
"Selling Holder"    --                                    Article IV
"Shares"   --                                             Recitals
"ShortForm Registration"    --                            Section 1.1
"Warrants"  --                                            Recitals

                                   ARTICLE IX
                                 MISCELLANEOUS

                  9.1  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.

                  9.2  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.

                  9.3  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 written receipt or by facsimile transmission or
mailed by prepaid 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

                                       13
<PAGE>

                           103rd  Floor
                           New York, New York 10048
                           Facsimile No.: (212) 938-5000
                           Attn.: General Counsel

                  with a copy to:

                           Swidler Berlin Shereff Friedman, LLP
                           The Chrysler Building
                           405 Lexington Avenue
                           New York, New York  10174
                           Facsimile No.:  (212) 938-5000
                           Attn.: General Counsel

                  If to any Investor, to the address set forth on the signature
page hereto.

All such notices, requests and other communications will (i) if delivered
personally to the address as provided in this Section 9.3, be deemed given upon
delivery, (ii) if delivered by facsimile transmission to the facsimile number as
provided in this Section 9.3, 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 9.3, 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 9.3, 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.

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

                  9.5  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 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.

                  9.6  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.

                                       14
<PAGE>

                  9.7  Governing Law; Forum; Process . This Agreement shall be
governed by and construed in accordance with the internal laws of the State of
New York, without giving effect to principles of conflicts of law. Each of the
parties hereto hereby irrevocably and unconditionally submits to the exclusive
jurisdiction of any court of the State of Delaware or any federal court sitting
in the State of Delaware for purposes of any suit, action or other proceeding
arising out of this Agreement (and agrees not to commence any action, suit or
proceedings relating hereto except in such courts). Each of the parties hereto
agrees that service of any process, summons, notice or document by U.S.
registered mail at its address set forth herein shall be effective service of
process for any action, suit or proceeding brought against it in any such court.
Each of the parties hereto hereby irrevocably and unconditionally waives any
objection to the laying of venue of any action, suit or proceeding arising out
of this Agreement, which is brought by or against it, in the courts of the State
of Delaware or any federal court sitting in the State of Delaware and hereby
further irrevocably and unconditionally waives and agrees not to plead or claim
in any such court that any such action, suit or proceeding brought in any such
court has been brought in an inconvenient forum.

                  9.8  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.

                  9.9  Additional Investors . Any transferee of a majority of
Registrable Securities held by an 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". An Investor shall no longer be
entitled to the benefits of this Agreement upon its transfer (in one or more
transactions) of a majority of the Registrable Securities held by such Investor.

                                    ARTICLE X
                             RULE 144 REPORTING

                        The Company hereby agrees as follows:

                  (a) The Company shall use its reasonable efforts to make and
keep public information available, as those terms are understood and defined in
Rule 144 under the Securities Act.

                  (b) The Company shall use its 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 while the Company is subject to such reporting requirements of the Exchange
Act.

                  (c) The Company shall furnish to each holder of Registrable
Securities forthwith upon a reasonable request a written statement by the
Company as to its compliance with the reporting requirements of Rule 144 and of
the Securities Act and the Exchange Act.

                                       15
<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/ Howard W. Lutnick
                                 ------------------------------
                                    Name:    Howard Lutnick
                                    Title:   Chairman and
                                             Chief Executive Officer

                              INITIAL INVESTORS:

                              WILLIAMS ENERGY MARKETING & TRADING COMPANY

                              By:  /s/ William C. Lawson
                                 ------------------------------
                                    Name:    William C. Lawson
                                    Title: Director, Energy Solutions
                                    Address:   One Williams Center
                                               Tulsa, Oklahoma 74172

                              DYNEGY INC.

                              By:  /s/ Kenneth E. Randolph
                                 ------------------------------
                                    Name: Kenneth E. Randolph
                                    Title:   Senior Vice President and
                                             General Counsel
                                    Address:          1000 Louisiana
                                                      Suite 5800
                                                      Houston, Texas 77002

                                       16<PAGE>

                            STOCK PURCHASE AGREEMENT

         This STOCK PURCHASE AGREEMENT (this "Agreement") is made and entered
into this 26th day of April, 2000 by and between Cantor Fitzgerald Securities
(the "Seller"), and eSpeed, Inc., (the "Purchaser").

         WHEREAS, simultaneously herewith, the Seller, the Purchaser and two
diversified energy companies, Dynegy, Inc. and The Williams Companies, Inc.
(each an "Anchor" and collectively the "Anchors") have entered into a business
relationship pursuant to which they will cooperate together to establish a
series of new marketplaces for the electronic and telephonic exchange of energy
and certain other products (the "Business Relationship");

         WHEREAS, each Anchor has agreed, pursuant to a Subscription Agreement
dated of even date hereof with the Purchaser, to which Seller is also a party
(the "Subscription Agreement"), to make an equity investment in the Purchaser
consisting, in pertinent part, of the purchase of 789,071 shares (or an
aggregate of 1,578,142 shares for the 2 Anchors) of Class A Common Stock, par
value $.01 per share, of the Purchaser (the "Class A Common Stock");

         WHEREAS, subject to the satisfaction of certain conditions relating to
investments in Qualified Verticals (as defined in the Subscription Agreement),
each Anchor has the right to make up to 4 additional investments of $25.0
million each in restricted shares of Class A Common Stock of the Company, at a
10% discount to the 10 Trading Day Average (as defined in the Subscription
Agreement) preceding the Purchaser's investment in the Qualified Vertical (the
"Additional Investment Right");

         WHEREAS, in furtherance of the Business Relationship and the
transactions contemplated thereby, the Seller is willing to sell, and the
Purchaser is willing to purchase, shares of Class B Common Stock of Purchaser,
par value $.01 per share, ("Class B Common Stock") representing (x) an aggregate
of 789,071 shares, representing half of the number of shares being sold to the
Anchors by Purchaser (the "Initial Shares"), and (y) each time an Additional
Investment Right is exercised, half of the number of shares purchased by the
Anchors, in the aggregate (the "Additional Shares"), in connection with each
such exercise, all subject to the terms and conditions set forth herein;

         WHEREAS, the purchase of the Initial Shares hereunder shall be
contingent upon, and consummated simultaneously with the Closing (as defined in
the Subscription Agreement), which is hereafter referred to as the "Subscription
Agreement Closing"; and

         WHEREAS, the purchase of the Additional Shares hereunder shall be
contingent upon, and consummated simultaneously with, the closing of each
Additional Investment Right.

<PAGE>

         NOW, THEREFORE, in consideration of the premises and of the mutual
agreements and covenants hereinafter set forth, and for good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
Seller and the Purchaser, intending to be legally bound, hereby agree as
follows:

1.       Terms of Purchase.

         1.1 Sale and Purchase of the Initial Shares. The Seller agrees to sell
to the Purchaser, and the Purchaser agrees to purchase from the Seller, the
Initial Shares for an aggregate cash purchase price of $25.0 million (the
"Purchase Price"). The Purchase Price shall be payable by wire transfer to an
account designated by Seller.

         1.2 Sale and Purchase of the Additional Shares. The Seller agrees to
sell to the Purchaser, and the Purchaser agrees to purchase from the Seller,
such number of Additional Shares (including shares purchased from the Company
upon exercise of a put or call as defined in Section 3(h) of the Subscription
Agreement), as shall equal half of the Additional Shares purchased from the
Anchors in the aggregate, upon each exercise of an Additional Investment Right,
provided that the Additional Shares shall be Class B Common Stock of Purchaser
(unless the Seller shall determine to substitute Class A Common Stock). The
purchase price per share of the Additional Shares (each referred to herein as
the "Additional Share Purchase Price") shall be the same purchase price per
share as is paid by the Anchors for the Class A Common Stock purchased by them
pursuant to the applicable exercise of an Additional Investment Right. The
Additional Share Purchase Price shall be payable by wire transfer to an account
designated by Seller. In the event that as a result of a recapitalization or
other similar transaction involving Purchaser, whether effected as a merger,
consolidation or otherwise, the Purchaser agrees with the Anchors that the
shares available for purchase upon exercise of an Additional Investment Right
shall consist of one or more securities which are issued or received in exchange
for the Class A Common Stock or Class B Common Stock of the Company, then the
provisions of this Section 1.2 and other Sections of this Agreement related
thereto, shall be deemed to include the security or securities so substituted.

         1.3 Initial Closing. The closing (the "Share Purchase Closing") of the
sale of the Initial Shares by the Seller to the Purchaser shall take place at
the offices of Purchaser, on the date of the Subscription Agreement Closing or
at such other time and place as the Seller and the Purchaser shall mutually
agree upon. At the Share Purchase Closing, the Seller shall deliver to the
Purchaser the Initial Shares against payment of the Purchase Price.

         1.4 Closings of Additional Investment Rights. The closing for each
Additional Share Purchase (each an "Additional Share Closing") shall take place
at the offices of Purchaser on the date of closing of each Additional Investment
Right (each an "Additional Investment Right Closing") or at such other time and
place as the Seller and Purchase shall mutually agree upon. At each Additional
Share Closing, the Seller shall deliver the Additional Shares to the Purchaser
against payment of the Additional Share Purchase Price.

<PAGE>

2.       Representations and Warranties of the Seller

         The Seller hereby makes the following representations and warranties to
the Purchaser:

         2.1 Organization of the Seller. The Seller is duly organized, validly
existing and in good standing under the laws of the jurisdiction of its
organization and has all requisite corporate power and authority to carry on its
business as now being conducted.

         2.2 Authority. The Seller has all requisite corporate power and
authority to enter into this Agreement and to perform all of its obligations
hereunder. The execution, delivery and performance of this Agreement and the
other documents and instruments to be executed by Seller pursuant hereto and the
consummation of the transactions contemplated hereby have been duly authorized
by all necessary corporate action on the part of the Seller. This Agreement has
been duly executed and delivered by the Seller and, assuming due authorization,
execution and delivery by the Purchaser, this Agreement constitutes the valid
and binding agreement of the Seller, enforceable against it in accordance with
its terms, except as may be limited by bankruptcy, moratorium and insolvency
laws and other laws affecting the rights of creditors' generally and except as
may be limited by the availability of equitable remedies.

         2.3 No Conflict. The execution and delivery of this Agreement and the
consummation of the transactions contemplated hereby will not, (i) conflict
with, or result in any violation or breach of, any provision of the Certificate
of Incorporation or Bylaws or other operative organizational documents of the
Seller, (ii) result in any violation or breach of, or constitute (with or
without notice or lapse of time, or both) a default (or give rise to a right of
termination, cancellation or acceleration of any obligation or loss of any
material benefit) under, or require a consent or waiver under, any of the terms,
conditions or provisions of any note, bond, mortgage, indenture, lease, contract
or other agreement, instrument or obligation to which the Seller or any of its
Subsidiaries is a party, or (iii) conflict with or violate any permit,
concession, franchise, license, judgment, order, decree, statute, law,
ordinance, rule or regulation applicable to the Seller or any of its
Subsidiaries or any its or their properties or assets, except in the case of
clauses (ii) and (iii) for any such conflicts, violations, breaches, defaults,
terminations, cancellations or accelerations which are not, individually or in
the aggregate, reasonably likely to have a material adverse effect on Seller and
its subsidiaries taken as a whole or on Seller's ability to consummate the
transactions contemplated hereby.

         2.4 Ownership of the Shares. The Seller owns and has good and
marketable title to the Initial Shares and the Additional Shares, free from all
liens, claims and encumbrances. At the Share Purchase Closing or Additional
Share Closing, as the case may be, the Purchaser will receive good and
marketable title to the Initial Shares or Additional Shares, as the case may be,
free from all liens, claims and encumbrances.

3.       Representations and Warranties of the Purchaser.

         The Purchaser hereby makes the following representations and warranties
to the Seller:

<PAGE>

         3.1 Organization of the Purchaser and its Subsidiaries. The Purchaser
is duly organized, validly existing and in good standing under the laws of the
jurisdiction of its organization and has all requisite corporate power and
authority to carry on its business as now being conducted.

         3.2 Authority. The Purchaser has all requisite corporate power and
authority to enter into this Agreement and to perform all of its obligations
hereunder. The execution, delivery and performance of this Agreement and the
other documents and instruments to be executed by Purchaser pursuant hereto and
the consummation of the transactions contemplated hereby have been duly
authorized by all necessary corporate action on the part of the Purchaser. This
Agreement has been duly executed and delivered by the Purchaser and, assuming
due authorization, execution and delivery by the Seller, this Agreement
constitutes the valid and binding agreement of the Purchaser, enforceable
against it in accordance with its terms, except as may be limited by bankruptcy,
moratorium and insolvency laws and other laws affecting the rights of creditors'
generally and except as may be limited by the availability of equitable
remedies.

         3.3 No Conflict. The execution and delivery of this Agreement and the
consummation of the transactions contemplated hereby will not, (i) conflict
with, or result in any violation or breach of, any provision of the Certificate
of Incorporation or Bylaws or other operative organizational documents of the
Purchaser, (ii) result in any violation or breach of, or constitute (with or
without notice or lapse of time, or both) a default (or give rise to a right of
termination, cancellation or acceleration of any obligation or loss of any
material benefit) under, or require a consent or waiver under, any of the terms,
conditions or provisions of any note, bond, mortgage, indenture, lease, contract
or other agreement, instrument or obligation to which the Purchaser or any of
its Subsidiaries is a party, or (iii) conflict with or violate any permit,
concession, franchise, license, judgment, order, decree, statute, law,
ordinance, rule or regulation applicable to the Purchaser or any of its
Subsidiaries or any its or their properties or assets, except in the case of
clauses (ii) and (iii) for any such conflicts, violations, breaches, defaults,
terminations, cancellations or accelerations which are not, individually or in
the aggregate, reasonably likely to have a material adverse effect on Purchaser
and its subsidiaries, taken as a whole, or on Purchaser's ability to consummate
the transactions contemplated hereby.

4.       Conditions to the Obligations of the Purchaser.

         The Purchaser's obligation to purchase and pay for the Initial Shares
or the Additional Shares, as the case may be, shall be subject to the
satisfaction, at or before the Share Purchase Closing, or the applicable
Additional Share Closing, as the case may be, of the following conditions (any
of which may be waived, in whole or in part, by the Purchaser):

         4.1 Representations and Warranties. All of the representations and
warranties of the Seller made in this Agreement shall have been true and
accurate in all material respects as of the date hereof and as of the Share
Purchase Closing or the applicable Additional Share Closing, as the case may be.

<PAGE>

         4.2 Delivery of Shares. Concurrently with the Share Purchase Closing,
or the applicable Additional Share Closing, as the case may be, the Seller shall
deliver to the Purchaser good and marketable title to the Initial Shares or
Additional Shares as the case may be, free from all liens, claims and
encumbrances.

         4.3 Subscription Agreement Closing or Additional Investment Right
Closing. The Subscription Agreement Closing or the applicable Additional
Investment Right Closing, as the case may be, shall have occurred.

5.       Conditions to the Obligation of the Seller.

         The Seller's obligation to sell, convey, transfer and assign the
Initial Shares or the Additional Shares, as the case may be, shall be subject to
the satisfaction, at or before the Share Purchase Closing, or the applicable
Additional Share Closing, as the case may be, of the following conditions (any
of which may be waived, in whole or in part, by the Seller):

         5.1 Representations and Warranties. All of the representations and
warranties of the Purchaser in this Agreement shall have been true and accurate
in all material respects as of the date hereof and as of the Share Purchase
Closing or the applicable Additional Share Closing, as the case may be.

         5.2 Closing of the Transaction Documents. The Subscription Agreement
Closing or the applicable Additional Investment Right Closing, as the case may
be shall have occurred.

         5.3 Purchase Price. The Seller shall have received from the Purchaser,
by wire transfer of immediately available funds, an amount in cash equal to the
Purchase Price or the Additional Share Purchase Price, as the case may be.

         6. Further Assurances. Subject to the terms and conditions hereof, each
party agrees that after the Share Purchase Closing or Additional Share Closing,
as the case may be, it will execute and deliver such documents as the other
party may reasonably request in order to consummate the transactions
contemplated hereby.

7.       Termination and Waiver.

         7.1 Termination. This Agreement may be terminated at any time by either
party if the Subscription Agreement with each Anchor shall be terminated or
otherwise by mutual agreement of the parties.

         7.2 Waiver. Each of the parties hereto may (i) extend the time for the
performance of any of the obligations or other acts of any other party hereto,
(ii) waive any inaccuracies in the representations and warranties contained
herein or in any document delivered pursuant hereto, or (iii) waive compliance
with any of the covenants, agreements or conditions contained herein. Any
agreement on the part of a party hereto to any such extension or waiver shall be
valid only if

<PAGE>

set forth in a written instrument signed by the party granting
such waiver. Such waiver or failure to insist upon strict compliance with such
obligation, covenant, agreement or condition shall not operate as a waiver of,
or estoppel with respect to, any subsequent or future failure.

8.       Miscellaneous.

         8.1 Headings.  Section headings contained in this Agreement are
included for convenience only and shall not affect the interpretation of any
provisions of this Agreement.

         8.2 Notices. Any notice, demand, request, waiver, or other
communication under this Agreement shall be in writing (including facsimile or
similar writing) and shall be deemed to have been duly given (i) on the date of
service if personally served, (ii) on the third day after mailing if mailed to
the party to whom notice is to be given, by first class mail, registered, return
receipt requested, postage prepaid or (iii) on the date sent if sent by
facsimile, to the parties at the following addresses or facsimile numbers with a
copy sent by mail as aforesaid on the same date (or at such other address or
facsimile number for a party as shall be specified by like notice):

         If to the Purchaser, to:           eSpeed, Inc.
                                            One World Trade Center
                                            103rd Floor
                                            New York, NY 10048
                                            Fax: (212) 938-3620
                                            Attention: General Counsel

         If to the Seller, to:              Cantor Fitzgerald Securities
                                            One World Trade Center
                                            105th Floor
                                            New York, NY 10048
                                            Fax: (212) 938-5000
                                            Attention: General Counsel

         8.3 Successors and Assigns. This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
assigns. Neither of the parties hereto shall assign any rights or delegate any
duties hereunder without the prior written consent of the other parties hereto,
and any assignment made without such consent shall be void and constitute a
default hereunder; provided that Seller may assign its obligation to sell Shares
or Additional Shares hereunder, in whole or in part, to a subsidiary or
affiliate of Seller that owns a sufficient number of shares of Class B Common
Stock to satisfy the assigned obligation.

         8.4 Governing Law.  This Agreement shall be construed in accordance
with, and governed by, the internal laws of the State of New York, without
giving effect to the principles of conflict of laws thereof.

         8.5 Entire Agreement. This Agreement sets forth the entire
understanding and agreement of the parties with respect to its subject matter
and supersedes any and all prior

<PAGE>

understandings, negotiations or agreements among the parties hereto, both
written and oral, with respect to such subject matter.

         8.6 Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original, but all of which,
when taken together, shall constitute one and the same agreement.

         8.7 Severability. In the event that any one or more of the provisions
contained in this Agreement shall for any reason be held to be invalid, illegal
or unenforceable in any respect, in whole or in part, the validity of the
remaining provisions shall not be affected and the remaining portion of any
provision held to be invalid, illegal or unenforceable shall in no way be
affected, prejudiced or disturbed thereby.

         8.8 No Prejudice.  This Agreement has been jointly prepared and
negotiated by the parties hereto and the terms hereof shall not be construed in
favor of or against any party on account of its participation in such
preparation.

         8.9 No Third Party Beneficiaries. This Agreement shall not confer any
rights or remedies upon any party other than the parties hereto and their
respective successors and permitted assigns.

         8.10 Amendment and Modification.  This Agreement may be amended or
modified only by written agreement executed by all parties hereto.

<PAGE>

         IN WITNESS WHEREOF, the Seller and the Purchaser have caused this
Agreement to be executed as of the date first written above.

                 eSpeed, Inc.

                 By:                 /s/ Howard W. Lutnick
                          --------------------------------------------
                          Name: Howard W. Lutnick
                          Title: Chairman and Chief Executive
                                    Officer

                 Cantor Fitzgerald Securities

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

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