Document:

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NEITHER THIS WARRANT NOR THE SHARES OF CLASS A COMMON STOCK ISSUABLE UPON
EXERCISE OF THIS WARRANT HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AND NEITHER THIS WARRANT NOR SUCH SHARES MAY BE SOLD, ENCUMBERED OR OTHERWISE
TRANSFERRED EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER SUCH
ACT OR AN EXEMPTION FROM SUCH REGISTRATION REQUIREMENT, AND, IF AN EXEMPTION
SHALL BE APPLICABLE, THE HOLDER SHALL HAVE DELIVERED AN OPINION OF COUNSEL
ACCEPTABLE TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.

Void after 5:00 p.m. Eastern Standard Time, on August 21, 2012.

                    WARRANT TO PURCHASE CLASS A COMMON STOCK

                                       OF

                                  ESPEED, INC.

         FOR VALUE RECEIVED, ESPEED, INC. (the "Company"), a Delaware
corporation, hereby certifies that UBS USA Inc. (the "Initial Holder"), or its
permitted assigns (together with the Initial Holder, the "Holder"), is entitled
to purchase from the Company, at any time or from time to time commencing on the
Exercise Date set forth in Section 4 hereof (as the same may be accelerated
pursuant to Section 4(b) hereof) and prior to 5:00 P.M., Eastern Standard Time,
on August 21, 2012 a total of 300,000 fully paid and non-assessable shares of
Class A Common Stock, par value $.01 per share, of the Company for a purchase
price of $8.75 per share. (Hereinafter, (i) said Class A Common Stock, together
with any other equity securities which may be issued by the Company with respect
thereto or in substitution therefor, is referred to as the "Class A Stock," (ii)
the shares of the Class A Stock purchasable hereunder are referred to as the
"Warrant Shares," (iii) the aggregate purchase price payable hereunder for the
Warrant Shares is referred to as the "Aggregate Warrant Price," (iv) the price
payable hereunder for each of the Warrant Shares is referred to as the "Per
Share Warrant Price," (v) this Warrant, and all warrants hereafter issued in
exchange or substitution for this Warrant are referred to as the "Warrant" and
(vi) the holder of this Warrant is referred to as the "Holder.") The number of
Warrant Shares and the securities (if applicable) for which this Warrant is
exercisable and the Per Share Warrant Price are subject to adjustment as
hereinafter provided under Section 3.

         1. EXERCISE OF WARRANT. This Warrant may be exercised, in whole at any
time or in part from time to time, commencing on the Exercise Date set forth in
Section 4 hereof (as the same may be accelerated pursuant to Section 4(b)
hereof) and prior to 5:00 P.M., Eastern Standard Time, on August 21, 2012 by the
Holder of this Warrant by the surrender of this Warrant (with the subscription
form at the end hereof duly executed) at the address set forth in Section 9(a)
hereof, together with proper payment of the Aggregate Warrant Price, or the
proportionate part thereof if this Warrant is exercised in part. The Aggregate
Warrant Price or Per Share Warrant Price shall be paid in cash, via wire
transfer to an account designated by the Company, or by certified or official
bank check payable to the order of the Company.

                  If this Warrant is exercised in part, the Holder shall be
entitled to receive a new Warrant covering the number of Warrant Shares in
respect of which this Warrant has not been exercised and setting forth the
proportionate part of the Aggregate Warrant Price applicable to such Warrant
Shares. Upon the surrender of this Warrant, for an exercise of this Warrant in
part, the Company will (a) issue and deliver a certificate or certificates in
the name of the Holder for the shares of the Class A Stock to which the Holder
shall be entitled for such partial exercise, and (b) issue and deliver a Warrant
in the name of

<PAGE>

the Holder for the remaining number of Warrant Shares in respect of which this
Warrant has not been exercised, pursuant to the provisions of this Warrant.

                  If this Warrant is exercised in whole, upon surrender of this
Warrant, the Company will issue a certificate or certificates in the name of the
Holder for the shares of the Class A Stock to which the Holder shall be
entitled, pursuant to the provisions of this Warrant.

                  No fractional shares shall be issued upon the exercise of this
Warrant. With respect to any fraction of a share called for upon any exercise
hereof, the Company shall pay to the Holder an amount in cash equal to such
fraction multiplied by the fair market value of a share as reasonably determined
by the Company's Board of Directors.

         2. RESERVATION OF WARRANT SHARES. The Company agrees that, prior to the
expiration of this Warrant, the Company from and as of the date hereof, will
have authorized and in reserve, and will keep available, solely for issuance or
delivery upon the exercise of this Warrant, the shares of the Class A Stock as
from time to time shall be receivable upon the exercise of this Warrant.

         3. ADJUSTMENTS FOR CORPORATE EVENTS. The number and kind of securities
issuable upon the exercise of this Warrant, the Per Share Warrant Price and the
number of Warrant Shares for which this Warrant may be exercised shall be
subject to adjustment from time to time in accordance with the following
provisions:

                  (a) Reorganization, Reclassification. In the event of a
reorganization, share exchange, or reclassification, other than a change in par
value, or from par value to no par value, or from no par value to par value or a
transaction described in subsection (b) or (c) below, this Warrant shall, after
such reorganization, share exchange or reclassification, be exercisable into the
kind and number of shares of stock or other securities or other property of the
Company which the holder of this Warrant would have been entitled to receive if
the holder had held the Warrant Shares issuable upon exercise of this Warrant
immediately prior to such reorganization, share exchange, or reclassification.
The provision of this Section 3(a) shall similarly apply to successive
reorganizations and reclassifications.

                  (b) Merger, Consolidation or Sale of All or Substantially All
Assets. In the event of a merger or consolidation to which the Company is a
party or the sale of all or substantially all of the assets of the Company, this
Warrant shall, after such merger, consolidation or sale, be exercisable for the
kind and number of shares of stock and/or other securities, cash or other
property which the holder of this Warrant would have been entitled to receive if
the holder had held the Warrant Shares issuable upon exercise of this Warrant
immediately prior to such merger, consolidation or sale. Any such merger,
consolidation or sale shall require, as a condition thereto, that such other
party to such merger, consolidation or sale agree in writing to assume this
Warrant. The provision of this Section 3(b) shall similarly apply to successive
mergers and transfers.

                  (c) Subdivision or Combination of Shares. In case outstanding
shares of Class A Stock shall be subdivided, the Per Share Warrant Price shall
be proportionately reduced as of the effective date of such subdivision, or as
of the date a record is taken of the holders of Class A Stock for the purpose of
so subdividing, whichever is earlier. In case outstanding shares of Class A
Stock shall be combined, the Per Share Warrant Price shall be proportionately
increased as of the effective date of such combination, or as of the date a
record is taken of the holders of Class A Stock for the purpose of so combining,
whichever is earlier.

                  (d) Stock Dividends. In case shares of Class A Stock are
issued as a dividend or other distribution on the Class A Stock, then the Per
Share Warrant Price shall be adjusted, as of the date

                                       2
<PAGE>

a record is taken of the holders of Class A Stock for the purpose of receiving
such dividend or other distribution (or if no such record is taken, as at the
earliest of the date of such declaration, payment or other distribution), to
that price determined by multiplying the Per Share Warrant Price in effect
immediately prior to such declaration, payment or other distribution by a
fraction (i) the numerator of which shall be the number of shares of Class A
Stock outstanding immediately prior to the declaration or payment of such
dividend or other distribution, and (ii) the denominator of which shall be the
total number of shares of Class A Stock outstanding immediately after the
declaration or payment of such dividend or other distribution. In the event that
the Company shall declare or pay any dividend on the Class A Stock payable in
any right to acquire Class A Stock for no consideration, then, for purposes of
calculating such adjustment, the Company shall be deemed to have made a dividend
payable in Class A Stock in an amount of shares equal to the maximum number of
shares issuable upon exercise of such rights to acquire Class A Stock.

                  (e) Adjustment of Aggregate Number of Warrant Shares Issuable.
Upon each adjustment of the Per Share Warrant Price under the provisions of this
Section 3, the aggregate number of Warrant Shares issuable upon exercise of this
Warrant shall be adjusted to an amount determined by multiplying the Warrant
Shares issuable prior to such adjustment by a fraction (x) the numerator of
which is the Per Share Warrant Price in effect immediately prior to the event
causing such adjustment (y) the denominator of which is the adjusted Per Share
Warrant Price.

                  (f) Minimum Adjustment. No adjustment of the Per Share Warrant
Price shall be made if the amount of any such adjustment would be an amount less
than 1% of the Per Share Warrant Price then in effect, but any such amount shall
be carried forward and an adjustment in respect thereof shall be made at the
time of and together with any subsequent adjustment which, together with such
amount and any other amount or amounts so carried forward, shall aggregate an
increase or decrease of 1% or more.

                  (g) Treasury Shares. The number of shares of Class A Stock at
any time outstanding shall not include any shares thereof then directly or
indirectly owned or held by or for the account of the Company.

                  (h) Notices. If at any time, (x) the Company shall declare a
stock dividend (or any other distribution except for cash dividends) on its
Class A Stock; (y) there shall be any capital reorganization or reclassification
of the Class A Stock, or any consolidation or merger to which the Company is a
party, or any sale or transfer of all of substantially all of the assets of the
Company; or (z) there shall be a voluntary or involuntary dissolution,
liquidation or winding-up of the Company; then, in any one or more of such
cases, the Company shall give written notice to the Holder, not less than 10
days before any record date or other date set for definitive action, or of the
date on which such reorganization, reclassification, sale, consolidation,
merger, dissolution, liquidation or winding up shall take place, as the case may
be. Such notice shall also set forth such facts as shall indicate the effect of
such action (to the extent such effect may be known at the date of such notice)
on the current Per Share Warrant Price and the kind and amount of Class A Stock
and other securities and property deliverable upon exercise of this Warrant.
Such notice shall also specify the date (to the extent known) as of which the
holders of the Class A Stock of record shall be entitled to exchange their Class
A Stock for securities or other property deliverable upon such reorganization,
reclassification, sale, consolidation, merger, dissolution, liquidation or
winding up, as the case may be. In addition, whenever the aggregate number of
Warrant Shares issuable upon exercise of this Warrant and Per Share Warrant
Price is adjusted as herein provided, the Chief Financial Officer of the Company
shall compute the adjusted number of Warrant Shares and Per Share Warrant Price
in accordance with the foregoing provisions and shall prepare a written
certificate

                                       3
<PAGE>

setting forth such adjusted number of Warrant Shares and Per Share Warrant
Price, and such written instrument shall promptly be delivered to the
recordholder of this Warrant.

4.       EXERCISE OF WARRANT.

                  (a) Exercise Date. This Warrant shall be vested immediately
and shall be exercisable as to all Warrant Shares commencing May 21, 2011 (the
"Exercise Date"), subject to acceleration as set forth in subsection (b) below.

                  (b) Acceleration of Exercisability. This Warrant shall become
exercisable as to (i) 150,000 of the Warrant Shares, if the Commitment Condition
(as defined in paragraph (i) below), is satisfied for the First Commitment
Period (as defined in paragraph (ii) below), and (ii) 150,000 of the Warrant
Shares, if the Commitment Condition is satisfied for the Second Commitment
Period (as defined in paragraph (ii) below). Satisfaction of the Commitment
Condition shall be evidenced by a Determination pursuant to paragraph (i) below.

                     (i)  Definition of Commitment Condition. A "Commitment
                          Condition" shall be deemed satisfied if, during the
                          applicable Commitment Period (as defined in paragraph
                          (ii) below), the Subscriber shall have performed,
                          satisfied and complied in all material respects with
                          the covenants, agreements and conditions required
                          thereby to be performed, satisfied or complied with by
                          the Bank (as defined in that certain UBS - Global
                          Fixed Income Transaction Fee Agreement, dated as of
                          August 13, 2002 between the Company and the Initial
                          Holder (the "Agreement")) in accordance with Annex II
                          of the Agreement, as the same may be amended from time
                          to time. For the avoidance of doubt, the Commitment
                          Condition shall be satisfied for a particular
                          Commitment Period even if the Subscriber has failed to
                          satisfy the Commitment Condition for any preceding
                          Commitment Period. Within 21 days of the end of each
                          Commitment Period, the Company shall notify the Holder
                          in writing as to whether the Commitment Condition has
                          been satisfied for such Commitment Period, together
                          with an explanation for such determination in
                          reasonable detail (the "Determination"). If the Holder
                          notifies the Company in writing, within fifteen (15)
                          days of receipt of the Determination of its objection
                          to the Determination, then no determination shall be
                          made until the Company and the Holder shall agree upon
                          an appropriate determination or a court of competent
                          jurisdiction shall make a determination by a
                          non-appealable order.

                   (ii)   Definition of Commitment Period. A shall mean each of
                          the following periods (i) the period beginning on
                          August 1, 2002 and ending on July 31, 2003 (the "First
                          Commitment Period"), and (ii) the period beginning on
                          August 1, 2003 and ending on June 30, 2004 (the
                          "Second Commitment Period").

         5. FULLY PAID STOCK; TAXES. The Company agrees that the shares of the
Class A Stock represented by each and every certificate for Warrant Shares
delivered on the proper exercise of this Warrant shall, at the time of such
delivery, be validly issued and outstanding, fully paid and non-assessable, and
not subject to preemptive rights, and the Company will take all such actions as
may be necessary to assure that the par value or stated value, if any, per share
of the Class A Stock is at all times equal to or less than the then Per Share
Warrant Price. The Company further covenants and agrees

                                       4

<PAGE>

that it will pay, when due and payable, any and all federal and state stamp,
original issue or similar taxes that may be payable in respect of the issuance
of any Warrant Shares or certificates therefor. The Holder covenants and agrees
that it shall pay, when due and payable, all of its federal, state and local
income or similar taxes that may be payable in respect of the issuance of any
Warrant Shares or certificates therefor, if any.

         6.       TRANSFER

                  (a) Securities Laws. Neither this Warrant nor the Warrant
Shares issuable upon the exercise hereof have been registered under the
Securities Act of 1933, as amended (the "Securities Act"), or under any state
securities laws and unless so registered may not be transferred, sold, pledged,
hypothecated or otherwise disposed of unless an exemption from such registration
is available. In the event the Holder desires to transfer this Warrant or any of
the Warrant Shares issued in accordance with the terms hereof, the Holder must
give the Company prior written notice of such proposed transfer including the
name and address of the proposed transferee, unless such transfer is a transfer
of the Warrant Shares pursuant to an effective registration statement. Such
transfer may be made only either (i) upon publication by the Securities and
Exchange Commission (the "Commission") of a ruling, interpretation, opinion or
"no action letter" based upon facts presented to said Commission, or (ii) upon
receipt by the Company of an opinion of counsel acceptable to the Company to the
effect that the proposed transfer will not violate the provisions of the
Securities Act, the Securities Exchange Act of 1934, as amended (the "Exchange
Act"), or the rules and regulations promulgated under either such act, or to the
effect that the Warrant or Warrant Shares to be sold or transferred have been
registered under the Securities Act of 1933, as amended, and that there is in
effect a current prospectus meeting the requirements of Subsection 10(a) of the
Securities Act, which is being or will be delivered to the purchaser or
transferee at or prior to the time of delivery of the certificates evidencing
the Warrant or Warrant Shares to be sold or transferred.

                  (b) Swap or Hedging Transactions. Without the prior written
consent of the Company, the Holder may not enter into any swap or other hedging
transaction relating to this Warrant, the Warrant Shares (prior to the issuance
thereof), or any interest therein. In no event shall the restrictions contained
in this paragraph apply to any Warrant Shares that have been issued.

                  (c) Transfer. Without the prior written consent of the
Company, neither this Warrant, nor any interest herein, may be sold, assigned,
transferred, pledged, encumbered or otherwise disposed of. Any sale, assignment,
transfer, pledge, encumbrance or other disposition of this Warrant attempted
contrary to the provisions of this Warrant, or any levy of execution, attachment
or other process attempted upon the Warrant, shall be null and void and without
effect. The provision of this Section 6(c) shall not be applicable to the
Warrant Shares.

                  (d) Legend and Stop Transfer Orders. Unless the Warrant Shares
have been registered under the Securities Act or eligible for resale pursuant to
Rule 144(k) under the Securities Act, upon exercise of any part of the Warrant
and the issuance of any of the Warrant Shares, the Company shall instruct its
transfer agent to enter stop transfer orders with respect to such shares, and
all certificates representing Warrant Shares shall bear on the face thereof
substantially the following legend, insofar as is consistent with Delaware law:

                           "The shares of Class A Common Stock represented by
                           this certificate have not been registered under the
                           Securities Act of 1933, as amended, and may not be
                           sold, offered for sale, assigned, transferred or
                           otherwise disposed of unless registered pursuant to
                           the provisions

                                       5

<PAGE>

                           of that Act or an opinion of counsel to the Company
                           is obtained stating that such disposition is in
                           compliance with an available exemption from such
                           registration."

         7. LOSS, ETC. OF WARRANT. Upon receipt of evidence satisfactory to the
Company of the loss, theft, destruction or mutilation of this Warrant, and of
indemnity reasonably satisfactory to the Company, if lost, stolen or destroyed,
and upon surrender and cancellation of this Warrant if mutilated, the Company
shall execute and deliver to the Holder a new Warrant of like date, tenor and
denomination.

         8. WARRANT HOLDER NOT SHAREHOLDER. Except as otherwise provided herein,
this Warrant does not confer upon the Holder any right to vote or to consent to
or receive notice as a shareholder of the Company, as such, in respect of any
matters whatsoever, or any other rights or liabilities as a shareholder, prior
to the exercise hereof.

         9. COMMUNICATION. No notice or other communication under this Warrant
shall be effective unless the same is in writing and is sent by overnight
courier, delivered in person or mailed by first-class mail, postage prepaid,
addressed to:

             (a) the Company at 135 East 57th Street, 3rd Floor, New York, New
York 10022, Attention: General Counsel, or such other address as the Company has
designated in writing to the Holder, or

             (b) the Holder at __________________________________, or such other
address as the Holder has designated in writing to the Company.

         10. HEADINGS. The headings of this Warrant have been inserted as a
matter of convenience and shall not affect the construction hereof.

         11. APPLICABLE LAW. This Warrant shall be governed by and construed in
accordance with the law of the State of New York without giving effect to the
principles of conflict of laws thereof.

         12. COMPLIANCE WITH OTHER INSTRUMENTS. Company represents and warrants
to Holder that the execution and delivery of this Warrant are not, and the
issuance of the Warrant Shares upon exercise of this Warrant in accordance with
the terms hereof will not be, inconsistent with the Company's charter or bylaws,
do not and will not contravene any law, governmental rule or regulation,
judgment or order applicable to the Company, and do not and will not conflict
with or contravene any provision of, or constitute a default under, any
indenture, mortgage, contract or other instrument of which the Company is a
party or by which it is bound or require the consent or approval of, the giving
of notice to, the registration or filing with or the taking of any action in
respect of or by, any Federal, state or local government authority or agency or
other person, except for the filing of notices pursuant to federal and state
securities laws, which filings will be effected by the time required thereby.

         13. REPRESENTATIONS AND WARRANTIES OF THE INITIAL HOLDER. The Initial
Holder, by acceptance hereof, represents and warrants to the Company that:

             (a) Knowledge and Experience. The Initial Holder has sufficient
knowledge and experience in financial and business matters to be capable of
evaluating the merits and risks of an unregistered, non-liquid investment such
as an investment in the Company and has evaluated the merits and risks of such
an investment. The Initial Holder understands that the offer and sale of the
Warrant and the Warrant Shares have not been approved or disapproved by the
Commission or any other governmental entity.

                                       6

<PAGE>

             (b) No other Representations or Warranties. No representations or
warranties have been made to the Initial Holder by the Company or any director,
officer, employee, agent or affiliate of the Company, other than the
representations of the Company set forth herein, and the decision of the Initial
Holder to acquire this Warrant is based on the information contained herein and
the Initial Holder's own independent investigation of the Company. The Initial
Holder acknowledges and agrees that the Company may now, or in the future, be in
negotiations with respect to, or enter into, arrangements, agreements or
understandings relating to other business opportunities and that the Company
does not have now, nor will it have at any time after execution of this Warrant,
any obligation to provide the Initial Holder with any information, other than
that which is contained in this Warrant and that which is disclosed in reports,
schedules, forms, registration statements, proxy statements and other documents
filed by the Company with the Commission.

             (c) Ability to Withstand Loss of Investment. The Initial Holder
understands that a total loss of the value of this Warrant is possible. The
Initial Holder acknowledges that it is capable of bearing a complete loss of the
value of this Warrant.

             (d) No Public Solicitation. The Initial Holder acknowledges that
neither the Company nor any person or entity acting on its behalf has offered to
sell any of the Warrants or the Warrant Shares to the Initial Holder by means of
any form of general solicitation or advertising, including without limitation
(i) any advertisement, article, notice or other communication published in any
newspaper, magazine or similar media, or broadcast over television or radio, and
(ii) any seminar or meeting whose attendees have been invited by any general
solicitation or general advertising.

             (e) Accredited Investor Status. The Initial Holder is an
"accredited investor" within the meaning of Rule 501 of Regulation D promulgated
under the Securities Act.

             (f) Acquiring for Investment Purposes. The Initial Holder is
acquiring this Warrant solely for its own account, for investment purposes only,
and not with a view towards their resale or distribution.

             (g) No Brokers, Finders, etc. The Initial Holder has not employed
any broker, financial advisor or finder, or incurred any liability for any
brokerage fees, commissions, finder's or other similar fees or expenses in
connection with the transactions contemplated by this Warrant.

             (h) No Action Taken to Invalidate Private Placement. The Initial
Holder has not taken any action that would result in the offering of this
Warrant and the Warrant Shares pursuant to this Warrant being treated as a
public offering and not a valid private offering under the law.

         14. MODIFICATION AND WAIVER. This Warrant and any provision hereof may
be changed, waived, discharged or terminated only by an instrument in writing
signed by the Company and the holder of this Warrant.

         15. BINDING EFFECT ON SUCCESSORS. This Warrant shall be binding upon
any entity succeeding the Company by merger, consolidation or acquisition of all
or substantially all of the Company's assets, and all of the obligations of the
Company relating to the Warrant Shares issuable upon the exercise of this
Warrant shall survive the exercise and termination of this Warrant and all of
the covenants and agreements of the Company shall inure to the benefit of the
successors and permitted assigns of the holder hereof.

                                       7

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Warrant to be signed by
a duly authorized officer as of this 21st day of August, 2002.

                                         ESPEED, INC.

                                         By: /s/ Lee Amaitis
                                            ---------------------------------
                                                  Name:  Lee Amaitis
                                                  Title: Global Chief Operating
                                                         Officer

ACCEPTED AND AGREED to:

UBS USA INC.

By: /s/ Per Dyrvik
   ---------------------------------
         Name:   Per Dyrvik
         Title:  Managing Director

                                       8

<PAGE>

                                  SUBSCRIPTION

         The undersigned, __________________________________________, pursuant
to the provisions of the foregoing Warrant, hereby agrees to subscribe for the
purchase of _________________________ shares of the Class A Common Stock of
eSPEED, INC. covered by said Warrant, and makes payment therefor in full at the
price per share provided by said Warrant.

Dated                                  Signature
     ---------------                            -------------------------------

                                              Address
                                                     --------------------------

                                                     --------------------------

                                   ASSIGNMENT

         FOR VALUE RECEIVED _________________________ hereby sells, assigns and
transfers unto _________________________ the foregoing Warrant and all rights
evidenced thereby, and does irrevocably constitute and appoint
_________________________, attorney, to transfer said Warrant on the books of
eSPEED, INC.

Dated                                  Signature
     ---------------                            -------------------------------

                                              Address
                                                     --------------------------

                                                     --------------------------

                               PARTIAL ASSIGNMENT

         FOR VALUE RECEIVED _________________________ hereby assigns and
transfers unto _________________________ the right to purchase
_________________________ shares of the Class A Common Stock of eSPEED, INC. by
the foregoing Warrant, and a proportionate part of said Warrant and the rights
evidenced hereby, and does irrevocably constitute and appoint
_________________________, attorney, to transfer that part of said Warrant on
the books of eSPEED, INC.

Dated                                  Signature
     ---------------                            -------------------------------

                                              Address
                                                     --------------------------

                                                     --------------------------

                                       9<PAGE>

                          REGISTRATION RIGHTS AGREEMENT

                                 BY AND BETWEEN

                                  ESPEED, INC.

                                       AND

                            THE INVESTOR NAMED HEREIN

                                       i

<PAGE>

                                TABLE OF CONTENTS

ARTICLE I PIGGYBACK REGISTRATIONS...........................................  3
   1.1    Right to Piggyback................................................  3
   1.2    Piggyback Expenses................................................  4
   1.3    Priority on Primary Registrations.................................  4
   1.4    Priority on Secondary Registrations...............................  4
ARTICLE II HOLDBACK AGREEMENTS..............................................  4
ARTICLE III REGISTRATION PROCEDURES.........................................  5
ARTICLE IV REGISTRATION EXPENSES............................................  7
   4.1    Registration Expenses.............................................  7
   4.2    Holders' Expenses.................................................  7
ARTICLE V UNDERWRITTEN AND OTHER OFFERINGS..................................  7
   5.1    Underwriting Agreement............................................  7
   5.2    Obligations of Participants.......................................  7
ARTICLE VI INDEMNIFICATION..................................................  8
   6.1    Company's Indemnification Obligations.............................  8
   6.2    Holder's Indemnification Obligations..............................  9
   6.3    Notices; Defense; Settlement......................................  9
   6.4    Indemnity Provision............................................... 10
ARTICLE VII DEFINITIONS..................................................... 10
   7.1    Terms............................................................. 10
   7.2    Defined Terms in Corresponding Sections........................... 12
ARTICLE VIII MISCELLANEOUS.................................................. 12
   8.1    Amendments and Waivers............................................ 12
   8.2    Successors and Assigns............................................ 12
   8.3    Notices........................................................... 12
   8.4    Headings.......................................................... 13
   8.5    Gender............................................................ 13
   8.6    Invalid Provisions................................................ 13
   8.7    Governing Law; Forum; Process..................................... 14
   8.8    Counterparts...................................................... 14
   8.9    No Assignment, Binding Effect..................................... 14

                                       ii

<PAGE>

                  REGISTRATION RIGHTS AGREEMENT (the "Agreement"), dated this
21st day of August, 2002, by and among eSpeed, Inc., a Delaware corporation (the
"Company") and UBS USA Inc. (the "Investor").

                                    RECITALS

                  WHEREAS, the Company desires to grant to the Investor
registration rights with respect to the shares (the "Shares") of Class A Common
Stock underlying the warrants to purchase 300,000 shares of Class A Common Stock
(the "Warrants") issued to the Investor on the date hereof and may grant
additional Warrants to purchase up to 200,000 additional shares in the future in
accordance with the renewal provisions of that certain Transaction Fee Agreement
(the "Renewal Warrants"), dated as of the date hereof, 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
                            PIGGYBACK REGISTRATIONS

                  1.1 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 S-8), 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 S-4), 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 the Investor 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 1.3 and 1.4 hereof. Such requests
for inclusion shall be in writing and delivered to the Company within five
business days after the Investor's receipt of the Notice and shall specify the
number of Registrable Securities intended to be 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 1.1 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 would not
be entitled to offer to sell under such registration whether by contractual
restriction or by law.

                                       3

<PAGE>

                  1.2 Piggyback Expenses. The Registration Expenses of the
Investor will be paid by the Company in all Piggyback Registrations

                  1.3 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 Cantor Fitzgerald Securities and its Affiliates, and their
successors and assigns ("Cantor") 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 Investor) exercising their respective piggyback
registration rights thereof based upon the total number of shares which such
holders (including the Investor) propose to include in such registration.

                  1.4 Priority on Secondary Registrations. If a Piggyback
Registration is an underwritten secondary registration on behalf of holders
(other than the Investor) 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, (ii) second, that number of other
shares of Common Stock proposed to be included in such registration by Cantor
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
Investor) exercising their respective piggyback registration rights thereof
based upon the total number of shares which such holders (including the
Investor) propose to include in such registration.

                                   ARTICLE II
                              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 a period recommended by the managing underwriters. The foregoing
shall not affect the ability of a holder of Registrable Securities to sell such
securities pursuant to Rule 144 under the Securities Act if approved by the
underwriters.

                                       4

<PAGE>

                                   ARTICLE III
                            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; 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 30 days (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;

                  (d)      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

                                       5

<PAGE>

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;

                  (e)      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 Selling Holders thereof to consummate the disposition of
such Registrable Securities;

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

                  (g)      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 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 (d) above, or in the case of a Black-Out 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,

                                       6

<PAGE>

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 IV
                             REGISTRATION EXPENSES

                  4.1      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 Section 1.2 of this Agreement.

                  4.2      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 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 V
                        UNDERWRITTEN AND OTHER OFFERINGS

                  5.1      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.

                  5.2      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

                                       7

<PAGE>

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 VI
                                INDEMNIFICATION

                  6.1      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") 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 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; 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 6.1 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 6.1 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 (d)
of Article III hereof, continues to use such Prospectus and in such case and

                                       8
<PAGE>

to the extent of, and with respect to, damages which arise after the holder
receives such notice.

                  6.2      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 6.1 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 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
6.2 are to be several and not joint.

                  6.3      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 6.1 or Section 6.2
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 6.1 or Section 6.2 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
exists 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

                                       9

<PAGE>

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. The indemnified
party will not, without the prior written consent of the indemnifying 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 indemnifying party or any Person
who controls such indemnifying party is a party to 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.

                  6.4      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 VII
                                  DEFINITIONS

                  7.1      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.

                                       10

<PAGE>

         "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 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.

         "Registrable Securities" means (i) the Class A Common Stock issued or
issuable at any time upon the exercise of the Warrants or Renewal Warrants (if
Renewal Warrants are issued), and (ii) any securities issued or received in
respect of, or in exchange or in substitution for any of the foregoing. 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. In addition, upon the breach by an Investor or its Affiliate of the
restrictions contained in Section 8.11, any Registrable Securities held by such
Investor shall cease to be Registrable Securities.

         "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.

                                       11

<PAGE>

         "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.

                  7.2      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
"Cantor"                   --                               Section 1.3
"Company"                  --                               Preamble
"Holder Indemnitees"       --                               Section 6.1
"Investor"                 --                               Preamble
"Notice"                   --                               Section 1.1
"Piggyback Registration"   --                               Section 2.1
"Registration Expenses"    --                               Section 4.1
"Renewal Warrants"         --                               Preamble
"Selling Holder"           --                               Article III
"Warrants"                 --                               Recitals

                                  ARTICLE VIII
                                 MISCELLANEOUS

                  8.1      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 Investor. 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.

                  8.2      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.

                  8.3      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

                                       12

<PAGE>

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.
                           135 East 57th Street, 3rd Floor
                           New York, New York  10022

                           Facsimile No.: (212) 829-4708
                           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 the 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 8.3, be deemed given upon
delivery, (ii) if delivered by facsimile transmission to the facsimile number as
provided in this Section 8.3, 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 8.3, 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 8.3, 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.

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

                  8.5      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.

                  8.6      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

                                       13

<PAGE>

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.

                  8.7      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 New York or any federal
court sitting in the State of New York 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 New York or any federal court sitting in the State of New York 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.

                  8.8      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. Delivery of a
facsimile version of one or more signatures to this Agreement shall be deemed
adequate delivery for purposes of this Agreement.

                  8.9      No Assignment; Binding Effect Neither this Agreement
nor any right, interest or obligation hereunder may be assigned by the Investor
without the prior written consent of the Company and any attempt to do so will
be null and void. Subject to the preceding sentence, this Agreement is binding
upon, inures to the benefit of and is enforceable by the parties hereto and
their respective successors and permitted assigns.

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

                                       14

<PAGE>

                                       COMPANY:

                                       eSpeed, Inc.

                                       By: /s/ Lee Amaitis
                                          -------------------------------
                                              Name:  Lee Amaitis
                                              Title: Global Chief Operating
                                                     Officer

                                       INVESTOR:

                                       UBS USA Inc.

                                       By: /s/ Per Dyrvik
                                          -------------------------------
                                              Name: Per Dyrvik
                                              Title: Managing Director
                                              Address: 680 Washington Blvd.,
                                                       Stamford, CT

                                       15

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