GUARANTY

Exhibit 4.2

E XECUTION V ERSION

BGC P ARTNERS , I NC .

Re: $150,000,000 Senior Notes due April 1, 2010

of

BGC P ARTNERS , L.P.

G UARANTY

D ATED AS OF M ARCH  31, 2008

T ABLE OF C ONTENTS

(Not a part of this Guaranty)

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S CHEDULES

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G UARANTY

BGC P ARTNERS , I NC .

199 Water Street

New York, NY 10338

$150,000,000 Senior Notes due April 1, 2010

OF

BGC P ARTNERS , L.P.

Dated as of March 31, 2008

This G UARANTY (the or this “Guaranty” ) is entered into by the undersigned BGC P ARTNERS , I NC . (successor by merger of BGC Partners, LLC and eSpeed, Inc.), a Delaware corporation (the “Guarantor” ), as of March 31, 2008.

R  E C I T A L S

A.    On the date hereof, BGC Partners, L.P. a Delaware limited partnership (the “Company” ), entered into the Note Purchase Agreement dated as of March 31, 2008 (the “Note Purchase Agreement” ), with the Purchasers named in Schedule A thereto (together with their successors and assigns, the “Purchasers” ).

B.    Pursuant to the Note Purchase Agreement the Company is issuing and selling $150,000,000 in aggregate principal amount of its Senior Notes due April 1, 2010 (the “Notes” ) on the terms provided in the Note Purchase Agreement. The Purchasers and each and every other holder from time to time of the Notes are sometimes hereinafter collectively referred to as the “Holders” and, individually, as a “Holder.”

C.    The Guarantor directly or indirectly owns all of the outstanding partnership interests of the Company.

D.    The Purchasers have required as a condition of their purchase of the Notes to be purchased by them that the Company cause the Guarantor to enter into this Guaranty as security for the Notes, and the Company has agreed to cause the Guarantor to execute this Guaranty in order to induce the Purchasers to purchase the Notes and thereby benefit the Company and its Affiliates by providing funds to enable the Company to have funds available for general partnership purposes.

E.    The Guarantor is desirous that the Purchasers enter into the Note Purchase Agreement and purchase the Notes, and by doing so the Purchasers will be conferring substantial financial and other benefits on the Guarantor.

F.    Pursuant to a guaranty (the “CFLP Guaranty” ), Cantor Fitzgerald, L.P., a Delaware limited partnership ( “CFLP” ), has also unconditionally guaranteed the Notes. Pursuant to a

subsidiary guaranty (the “Subsidiary Guaranty” ), Subsidiary Guarantors (as therein defined) may in the future unconditionally guarantee the Notes. CFLP and the Subsidiary Guarantors, together with any other Person which shall become Guarantor of the Notes pursuant to the terms of the Note Purchase Agreement or this Guaranty, are sometimes hereinafter referred to individually as an “other Guarantor” and collectively as the “other Guarantors”.

N OW , T HEREFORE , as required by the Note Purchase Agreement and in consideration of the premises and other good and valuable consideration, the receipt and sufficiency whereof are hereby acknowledged, the Guarantor hereby covenants and agrees as follows:

S ECTION  1.        D EFINITIONS .

Capitalized terms used herein shall have the meanings set forth in Schedule A hereto unless herein defined or the context shall otherwise require.

S ECTION  2.        G UARANTY OF N OTES AND N OTE P URCHASE A GREEMENT .

The Guarantor hereby irrevocably, absolutely and unconditionally guarantees to the Holders: (a) the full and prompt payment of the principal of, premium, if any, and interest on the Notes from time to time outstanding, as and when such payments shall become due and payable, whether by lapse of time, upon redemption or prepayment, by extension or by acceleration or declaration or otherwise (including (to the extent legally enforceable) interest due on overdue payments of principal, premium, if any, or interest at the rate set forth in the Notes and interest accruing at the then applicable rate provided in the Notes after the filing of any petition in bankruptcy, or the commencement of any insolvency, reorganization or like proceeding, relating to the Company, whether or not a claim for post-filing or post-petition interest is allowed in such proceeding) in Federal or other immediately available funds of the United States of America which at the time of payment or demand therefor shall be legal tender for the payment of public and private debts, (b) the full and prompt performance and observance by the Company of each and all of the obligations, covenants and agreements required to be performed or owed by the Company under the terms of the Notes and the Note Purchase Agreement and (c) the full and prompt payment, upon demand by any Holder, of all costs and expenses, legal or otherwise (including attorneys’ fees), if any, as shall have been expended or incurred in the protection or enforcement of any rights, privileges or liabilities in favor of the Holders under or in respect of the Notes, the Note Purchase Agreement or under this Guaranty or in any consultation or action in connection therewith or herewith and in each and every case irrespective of the validity, regularity, or enforcement of any of the Notes or Note Purchase Agreement or any of the terms thereof or any other like circumstance or circumstances.

S ECTION  3.        G UARANTY OF P AYMENT AND P ERFORMANCE .

This is a guarantee of payment and performance and the Guarantor hereby waives, to the fullest extent permitted by law, any right to require that any action on or in respect of any Note, the Note Purchase Agreement or any other Guaranty be brought against the Company, CFLP, any Subsidiary Guarantor or any other Person or that resort be had to any direct or

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indirect security for the Notes or for this Guaranty or any other remedy. Any Holder may, at its option, proceed hereunder against the Guarantor in the first instance to collect monies when due, the payment of which is guaranteed hereby, without first proceeding against the Company or any other Person and without first resorting to any direct or indirect security for the Notes or for this Guaranty or any other remedy. The liability of the Guarantor hereunder shall in no way be affected or impaired by any acceptance by any Holder of any direct or indirect security for, or other guaranties of, any Debt, liability or obligation of the Company or any other Person to any Holder or by any failure, delay, neglect or omission by any Holder to realize upon or protect any such guarantees, Debt, liability or obligation or any notes or other instruments evidencing the same or any direct or indirect security therefor or by any approval, consent, waiver, or other action taken, or omitted to be taken by any such Holder.

S ECTION  4.        G ENERAL P ROVISIONS R ELATING TO THE G UARANTY .

(a)    The Guarantor hereby consents and agrees that any Holder or Holders from time to time, with or without any further notice to or assent from the other Guarantors may, without in any manner affecting the liability of the Guarantor under this Guaranty, and upon such terms and conditions as any such Holder or Holders may deem advisable:

(1)    extend in whole or in part (by renewal or otherwise), modify, change, compromise, release or extend the duration of the time for the performance or payment of any Debt, liability or obligation of the Company or of any other Person secondarily or otherwise liable for any Debt, liability or obligations of the Company on the Notes, or waive any Default with respect thereto, or waive, modify, amend or change any provision of any other agreement or this Guaranty; or

(2)    sell, release, surrender, modify, impair, exchange or substitute any and all property, of any nature and from whomsoever received, held by, or for the benefit of, any such Holder as direct or indirect security for the payment or performance of any Debt, liability or obligation of the Company or of any other Person secondarily or otherwise liable for any Debt, liability or obligation of the Company on the Notes; or

(3)    settle, adjust or compromise any claim of the Company against any other Person secondarily or otherwise liable for any Debt, liability or obligation of the Company on the Notes.

The Guarantor hereby ratifies and confirms any such extension, renewal, change, sale, release, waiver, surrender, exchange, modification, amendment, impairment, substitution, settlement, adjustment or compromise and that the same shall be binding upon it, and hereby waives, to the fullest extent permitted by law, any and all defenses, counterclaims or offsets which it might or could have by reason thereof, it being understood that the Guarantor shall at all times be bound by this Guaranty and remain liable hereunder.

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(b)    The Guarantor hereby waives, to the fullest extent permitted by law:

(1)    notice of acceptance of this Guaranty by the Holders or of the creation, renewal or accrual of any liability of the Company, present or future, or of the reliance of such Holders upon this Guaranty (it being understood that every Debt, liability and obligation described in Section 2 hereof shall conclusively be presumed to have been created, contracted or incurred in reliance upon the execution of this Guaranty);

(2)    demand of payment by any Holder from the Company or any other Person indebted in any manner on or for any of the Debt, liabilities or obligations hereby guaranteed; and

(3)    presentment for the payment by any Holder or any other Person of the Notes or any other instrument, protest thereof and notice of its dishonor to any party thereto and to the Guarantor.

The obligations of the Guarantor under this Guaranty and the rights of any Holder to enforce such obligations by any proceedings, whether by action at law, suit in equity or otherwise, shall not be subject to any reduction, limitation, impairment or termination (other than by payment in full of the Notes and the obligations of the Company under the Note Purchase Agreement), whether by reason of any claim of any character whatsoever or otherwise and shall not be subject to any defense, set-off, counterclaim (other than any compulsory counterclaim), recoupment or termination whatsoever.

(c)    The obligations of the Guarantor hereunder shall be binding upon the Guarantor and its successors and assigns, and shall remain in full force and effect until the entire principal, interest and premium, if any, on the Notes and all other sums due pursuant to Section 2 shall have been paid and such obligations shall not be affected, modified or impaired upon the happening from time to time of any event, including without limitation any of the following, whether or not with notice to or the consent of the Guarantor:

(1)    the genuineness, validity, regularity or enforceability of the Notes, the Note Purchase Agreement, any other Guaranty or any other agreement or any of the terms of any thereof, the continuance of any obligation on the part of the Company, any other Guarantor or any other Person on or in respect of the Notes or under the Note Purchase Agreement, any other Guaranty or any other agreement or the power or authority or the lack of power or authority of the Company to issue the Notes or the Company to execute and deliver the Note Purchase Agreement or any other agreement or of any other Guarantor to execute and deliver the other Guaranty to which it is a party or to perform any of its obligations hereunder or thereunder or the existence or continuance of the Company, any other Guarantor or any other Person as a legal entity; or

(2)    any default, failure or delay, willful or otherwise, in the performance by the Company, any other Guarantor or any other Person of any obligations of any kind or character whatsoever under the Notes, the Note Purchase Agreement, this Guaranty, any other Guaranty or any other agreement; or

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(3)    any creditors’ rights, bankruptcy, receivership or other insolvency proceeding of the Company, any other Guarantor or any other Person or in respect of the property of the Company, any other Guarantor or any other Person or any merger, consolidation, reorganization, dissolution, liquidation, the sale of all or substantially all of the assets of or winding up of the Company, any other Guarantor or any other Person; or

(4)    impossibility or illegality of performance on the part of the Company, any other Guarantor or any other Person of its obligations under the Notes, the Note Purchase Agreement, this Guaranty, any other Guaranty or any other agreement; or

(5)    in respect of the Company, any other Guarantor or any other Person, any change of circumstances, whether or not foreseen or foreseeable, whether or not imputable to the Company, any other Guarantor or any other Person, or other impossibility of performance through fire, explosion, accident, labor disturbance, floods, droughts, embargoes, wars (whether or not declared), civil commotion, acts of God or the public enemy, delays or failure of suppliers or carriers, inability to obtain materials, action of any federal or state regulatory body or agency, change of law or any other causes affecting performance, or any other force majeure, whether or not beyond the control of the Company, any other Guarantor or any other Person and whether or not of the kind hereinbefore specified; or

(6)    any attachment, claim, demand, charge, Lien, order, process, encumbrance or any other happening or event or reason, similar or dissimilar to the foregoing, or any withholding or diminution at the source, by reason of any taxes, assessments, expenses, Debt, obligations or liabilities of any character, foreseen or unforeseen, and whether or not valid, incurred by or against the Company, the Guarantor, any other Guarantor or any other Person or any claims, demands, charges or Liens of any nature, foreseen or unforeseen, incurred by the Company, the Guarantor, any other Guarantor or any other Person, or against any sums payable in respect of the Notes or under the Note Purchase Agreement, this Guaranty, any other Guaranty or other agreement so that such sums would be rendered inadequate or would be unavailable to make the payments herein provided; or

(7)    any order, judgment, decree, ruling or regulation (whether or not valid) of any court of any nation or of any political subdivision thereof or any body, agency, department, official or administrative or regulatory agency of any thereof or any other action, happening, event or reason whatsoever which shall delay, interfere with, hinder or prevent, or in any way adversely affect, the performance by the Company, the Guarantor, any other Guarantor or any other Person of its respective obligations under or in respect of the Notes, the Note Purchase Agreement, this Guaranty, any other Guaranty or any other agreement; or

(8)    the failure of the Guarantor to receive any benefit from or as a result of its execution, delivery and performance of this Guaranty; or

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(9)    any failure or lack of diligence in collection or protection, failure in presentment or demand for payment, protest, notice of protest, notice of default and of nonpayment, any failure to give notice to the Guarantor of failure of the Company, any other Guarantor or any other Person to keep and perform any obligation, covenant or agreement under the terms of the Notes, the Note Purchase Agreement, this Guaranty, any other Guaranty or any other agreement or failure to resort for payment to the Company, any other Guarantor or to any other Person or to any other guaranty or to any property, security, Liens or other rights or remedies; or

(10)    the acceptance of any additional security or other guaranty, the advance of additional money to the Company or any other Person, the renewal or extension of the Notes or amendments, modifications, consents or waivers with respect to the Notes, the Note Purchase Agreement, this Guaranty, any other Guaranty or any other agreement, or the sale, release, substitution or exchange of any security for the Notes; or

(11)    any merger or consolidation of the Company, the Guarantor, any other Guarantor or any other Person into or with any other Person or any sale, lease, transfer or other disposition of any of the assets of the Company, any other Guarantor or any other Person to any other Person, or any change in the ownership of any shares of the Company, the Guarantor, any other Guarantor or any other Person; or

(12)    any defense whatsoever that: (i) the Company or any other Person might have to the payment of the Notes (principal, premium, if any, or interest), other than payment thereof in Federal or other immediately available funds, or (ii) the Company or any other Person might have to the performance or observance of any of the provisions of the Notes, the Note Purchase Agreement, this Guaranty, any other Guaranty or any other agreement, whether through the satisfaction or purported satisfaction by the Company, the Guarantor, any other Guarantor or any other Person of its debts due to any cause such as bankruptcy, insolvency, receivership, merger, consolidation, reorganization, dissolution, liquidation, winding-up or otherwise, other than the defense of indefeasible payment in full in cash of the Notes; or

(13)    any act or failure to act with regard to the Notes, the Note Purchase Agreement, this Guaranty, any other Guaranty or any other agreement or anything which might vary the risk of the Guarantor, any other Guarantor or any other Person; or

(14)    any other circumstance which might otherwise constitute a defense available to, or a discharge of, the Guarantor, any other Guarantor or any other Person in respect of the obligations of the Guarantor, any other Guarantor or other Person under this Guaranty, any other Guaranty or any other agreement, other than the defense of indefeasible payment in full in cash of the Notes;

provided that the specific enumeration of the above-mentioned acts, failures or omissions shall not be deemed to exclude any other acts, failures or omissions, though not specifically mentioned above, it being the purpose and intent of this Guaranty and the parties hereto that the obligations of the Guarantor hereunder shall be absolute and unconditional and shall not be discharged,

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impaired or varied except by the payment of the principal of, premium, if any, and interest on the Notes in accordance with their respective terms whenever the same shall become due and payable as in the Notes provided and all other sums due and payable under the Note Purchase Agreement, at the place specified in and all in the manner and with the effect provided in the Notes and the Note Purchase Agreement, as each may be amended or modified from time to time. Without limiting the foregoing, it is understood that repeated and successive demands may be made and recoveries may be had hereunder as and when, from time to time, the Company shall default under or in respect of the terms of the Notes or the Note Purchase Agreement and that notwithstanding recovery hereunder for or in respect of any given default or defaults by the Company under the Notes or the Note Purchase Agreement, this Guaranty shall remain in full force and effect and shall apply to each and every subsequent default.

(d)    All rights of any Holder may be transferred or assigned at any time and shall be considered to be transferred or assigned at any time or from time to time upon the transfer of any Note whether with or without the consent of or notice to the Guarantor under this Guaranty or to the Company.

(e)    To the extent of any payments made under this Guaranty, the Guarantor shall be subrogated to the rights of the Holder upon whose Notes such payment was made, but the Guarantor covenants and agrees that such right of subrogation shall be subordinate in right of payment to the prior indefeasible final payment in cash in full of all amounts due and owing by the Company with respect to the Notes and the Note Purchase Agreement and by the Guarantor under this Guaranty, and the Guarantor shall not take any action to enforce such right of subrogation, and the Guarantor shall not accept any payment in respect of such right of subrogation, until all amounts due and owing by the Company under or in respect of the Notes and the Note Purchase Agreement and all amounts due and owing by the Guarantor hereunder have indefeasibly been finally paid in cash in full. If any amount shall be paid to the Guarantor in violation of the preceding sentence at any time prior to the later of the indefeasible payment in cash in full of the Notes and all other amounts payable under the Notes, the Note Purchase Agreement and this Guaranty, such amount shall be held in trust for the benefit of the Holders and shall forthwith be paid to the Holders to be credited and applied to the amounts due or to become due with respect to the Notes and all other amounts payable under the Note Purchase Agreement and this Guaranty, whether matured or unmatured. The Guarantor acknowledges that it has received direct and indirect benefits from the financing arrangements contemplated by the Note Purchase Agreement and that the waiver set forth in this paragraph (e) is knowingly made as a result of the receipt of such benefits.

(f)    The Guarantor agrees that to the extent the Company, any other Guarantors or any other Person makes any payment on any Note, which payment or any part thereof is subsequently invalidated, voided, declared to be fraudulent or preferential, set aside, recovered, rescinded or is required to be retained by or repaid to a trustee, receiver, or any other Person under any bankruptcy code, common law, or equitable cause, then and to the extent of such payment, the obligation or the part thereof intended to be satisfied shall be revived and continued in full force and effect with respect to the Guarantor’s obligations hereunder, as if said payment had not been made. The liability of the Guarantor hereunder shall not be reduced or discharged, in whole or in part, by any payment to any Holder from any source that is thereafter paid,

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returned or refunded in whole or in part by reason of the assertion of a claim of any kind relating thereto, including, but not limited to, any claim for breach of contract, breach of warranty, preference, illegality, invalidity, or fraud asserted by any account debtor or by any other Person.

(g)    No Holder shall be under any obligation: (1) to marshall any assets in favor of the Guarantor or in payment of any or all of the liabilities of the Company under or in respect of the Notes or the obligations of the Guarantor hereunder or (2) to pursue any other remedy that the Guarantor may or may not be able to pursue themselves and that may lighten the Guarantor’s burden, any right to which the Guarantor hereby expressly waives.

(h)    The obligations of the Guarantor under this Guaranty rank pari passu in right of payment with all other Debt of the Guarantor which is not secured or which is not expressly subordinated in right of payment to any other Debt of the Guarantor.

S ECTION  5.        R EPRESENTATIONS AND W ARRANTIES OF THE G UARANTOR .

The Guarantor represents and warrants to each Purchaser that:

Section 5.1.    Organization; Power and Authority .    The Guarantor is a corporation duly incorporated, validly existing and in good standing under the laws of its jurisdiction of incorporation, and is duly qualified as a foreign corporation and is in good standing in each jurisdiction in which such qualification is required by law, other than those jurisdictions as to which the failure to be so qualified or in good standing could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect. The Guarantor has the legal power and authority to own or hold under lease the properties it purports to own or hold under lease, to transact the business it transacts and proposes to transact, to execute and deliver this Guaranty and to perform the provisions hereof.

Section 5.2.    Authorization, Etc .    This Guaranty has been duly authorized by all necessary legal action on the part of the Guarantor, and this Guaranty constitutes a legal, valid and binding obligation of the Guarantor enforceable against the Guarantor in accordance with its terms, except as such enforceability may be limited by (a) applicable bankruptcy, insolvency, reorganization, moratorium or other similar laws affecting the enforcement of creditors’ rights generally and (b) general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law).

Section 5.3.    Disclosure .    Since December 31, 2006, there has been no change in the financial condition, operations, business, properties or prospects of the Guarantor or any Subsidiary except changes that individually or in the aggregate could not reasonably be expected to have a Material Adverse Effect. There is no fact known to the Guarantor that could reasonably be expected to have a Material Adverse Effect that has not been set forth herein.

Section 5.4.    Organization and Ownership of Shares of Subsidiaries; Affiliates . (a)  Schedule 5.4 contains (except as noted therein) complete and correct lists (i) of the Guarantor’s Subsidiaries, showing, as to each Subsidiary, the correct name thereof, the jurisdiction of its organization, the percentage of shares of each class of its Capital Stock or

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similar equity interests outstanding owned by the Guarantor and each other Subsidiary, (ii) of the Guarantor’s Affiliates, other than Subsidiaries, and (iii) of the Guarantor’s directors and senior officers.

(b)    Ownership interests in the Guarantor are as set forth in Schedule 5.4 .

(c)    All of the outstanding shares of Capital Stock or similar equity interests of each Subsidiary shown in Schedule 5.4 as being owned by the Guarantor and its Subsidiaries have been validly issued, are fully paid and nonassessable and are owned by the Guarantor or another Subsidiary free and clear of any Lien (except as otherwise disclosed in Schedule 5.4 ).

(d)    Each Subsidiary identified in Schedule 5.4 is a partnership, limited liability company, corporation or other legal entity duly organized, validly existing and in good standing under the laws of its jurisdiction of organization, and is duly qualified as a foreign corporation or other legal entity and is in good standing in each jurisdiction in which such qualification is required by law, other than those jurisdictions as to which the failure to be so qualified or in good standing could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect. Each such Subsidiary has the partnership, limited liability, corporate or other power and authority to own or hold under lease the properties it purports to own or hold under lease and to transact the business it transacts and proposes to transact.

(e)    No Subsidiary is a party to, or otherwise subject to, any legal, regulatory, contractual or other restriction (other than this Guaranty, the agreements listed on Schedule 5.4 and customary limitations imposed by corporate law or similar statutes and regulatory restrictions) restricting in any Material respect the ability of such Subsidiary to pay dividends out of profits or make any other similar distributions of profits to the Guarantor or any of its Subsidiaries that owns outstanding shares of Capital Stock or similar equity interests of such Subsidiary.

Section 5.5.    Financial Statements; Material Liabilities .  The Guarantor has delivered to each Purchaser copies of the financial statements of the Guarantor and its Subsidiaries listed on Schedule 5.5 . All of said financial statements (including in each case the related schedules and notes) fairly present in all material respects the consolidated financial position of the Guarantor and its Subsidiaries as of the respective dates specified in such financial statements and the consolidated results of their operations and cash flows for the respective periods so specified and have been prepared in accordance with GAAP consistently applied throughout the periods involved except as set forth in the notes thereto (subject, in the case of any interim financial statements, to normal year-end adjustments). The Guarantor and its Subsidiaries do not have any Material liabilities that are not disclosed on such financial statements or otherwise disclosed in the Disclosure Documents.

Section 5.6.    Compliance with Laws, Other Instruments, Etc .  (a) The execution, delivery and performance by the Guarantor of this Guaranty will not (i) contravene, result in any breach of, or constitute a default under, or result in the creation of any Lien in respect of any property of the Guarantor or any Subsidiary under, any indenture, mortgage, deed of trust, loan, purchase or credit agreement, lease, corporate charter or by-laws, limited liability company agreement,

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partnership agreement or any other agreement or instrument to which the Guarantor or any Subsidiary is bound or by which the Guarantor or any Subsidiary or any of their respective properties may be bound or affected, (ii) conflict with or result in a breach of any of the terms, conditions or provisions of any order, judgment, decree, or ruling of any court, arbitrator or Governmental Authority applicable to the Guarantor or any Subsidiary, (iii) violate any provision of any statute or other rule or regulation of any Governmental Authority applicable to the Guarantor or any Subsidiary, or (iv) require any consent or approval of the limited partners or, in the case of the general partner of the Guarantor, any consent or approval which has not been obtained and which is not in full force and effect, the stockholders of the CF General Partner, the partners or stockholders of any of the Guarantor’s Subsidiaries or any other third party, except in the case of the foregoing clauses (i) and (ii), any contravention, breach, default, Lien or conflict which individually or in the aggregate could not reasonably be expected to have a Material Adverse Effect.

(b)    Without limiting clause (a) of this Section 5.6 :

(i)    FINRA has been designated and currently is the examining authority for BGC Financial Inc. ( “BGCFI” ). CFBGCFI is a member organization in good standing of FINRA and is duly registered as a broker-dealer, in good standing, in each state or other jurisdiction in which the character of the properties owned by it or the transaction of its business makes such registration necessary. BGCFI and its Affiliates possess all of the licenses and registrations from and with any governmental agency or instrumentality, or any securities or commodities exchange or self-regulatory organization, necessary or appropriate for the conduct of its business, as such business is presently conducted; and

(ii)    Neither the Guarantor nor any Subsidiary is in arrears with respect to any assessment made upon it by SIPC that is due and payable.

Section 5.7.    Governmental Authorizations, Etc .  No consent, approval or authorization of, or registration, filing or declaration with, any Governmental Authority is required in connection with the execution, delivery or performance by the Guarantor of this Guaranty.

S ection 5.8.    Litigation; Observance of Agreements, Statutes and Orders.   (a) There are no actions, suits, investigations or proceedings pending or, to the knowledge of the Guarantor, threatened against or affecting the Guarantor or any Subsidiary or any property of the Guarantor or any Subsidiary in any court or before any arbitrator of any kind or before or by any Governmental Authority that, individually or in the aggregate, could reasonably be expected to have a Material Adverse Effect.

(b)    Neither the Guarantor nor any Subsidiary is in default under any term of any agreement or instrument to which it is a party or by which it is bound, or any order, judgment, decree or ruling of any court, arbitrator or Governmental Authority or is in violation of any applicable law, ordinance, rule or regulation (including without limitation Environmental Laws or the USA Patriot Act) of any Governmental Authority, which default or violation, individually or in the aggregate, could reasonably be expected to have a Material Adverse Effect.

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Section 5.9.    Taxes .  The Guarantor and its Subsidiaries have filed all tax returns that are required to have been filed in any jurisdiction and that are Material, and have paid all taxes shown to be due and payable on such returns and all other taxes and assessments levied upon them or their properties, assets, income or franchises, to the extent such taxes and assessments have become due and payable and before they have become delinquent, except for any taxes and assessments (a) the amount of which is not individually or in the aggregate Material or (b) the amount, applicability or validity of which is currently being contested in good faith by appropriate proceedings and with respect to which the Guarantor or a Subsidiary, as the case may be, has established adequate reserves in accordance with GAAP. The Guarantor knows of no basis for any other tax or assessment that could reasonably be expected to have a Material Adverse Effect. The charges, accruals and reserves on the books of the Guarantor and its Subsidiaries in respect of federal, state or other taxes for all fiscal periods are adequate. The federal income tax liabilities of eSpeed, Inc., the predecessor to the Guarantor and its Subsidiaries have been finally determined (whether by reason of completed audits or the statute of limitations having run) for all Fiscal Years up to and including the Fiscal Year ended December 31, 2003.

Section 5.10.    Title to Property; Leases .  The Guarantor and its Subsidiaries have good and sufficient title to their respective properties that individually or in the aggregate are Material, including all such properties reflected in the most recent audited balance sheet referred to in Section 5.5 or purported to have been acquired by the Guarantor or any Subsidiary after said date (except as sold or otherwise disposed of in the ordinary course of business), in each case free and clear of Liens prohibited by this Guaranty. All leases that individually or in the aggregate are Material are valid and subsisting and are in full force and effect in all material respects.

Section 5.11.    Licenses, Permits, Etc .    (a) The Guarantor and its Subsidiaries own or possess all licenses, permits, franchises, authorizations, patents, copyrights, proprietary software, service marks, trademarks and trade names, or rights thereto, that individually or in the aggregate are Material, without known conflict with the rights of others.

(b)    To the best knowledge of the Guarantor, no product of the Guarantor or any of its Subsidiaries infringes in any respect any license, permit, franchise, authorization, patent, copyright, proprietary software, service mark, trademark, trade name or other right owned by any other Person, except as would not individually or in the aggregate have a Material Adverse Effect.

(c)    To the best knowledge of the Guarantor, there is no Material violation by any Person of any right of the Guarantor or any of its Subsidiaries with respect to any patent, copyright, proprietary software, service mark, trademark, trade name or other right owned or used by the Guarantor or any of its Subsidiaries.

Section 5.12.    Compliance with ERISA .  (a) The Guarantor and each ERISA Affiliate have operated and administered each Plan in compliance with all applicable laws except for such instances of noncompliance as have not resulted in and could not reasonably be expected to result in a Material Adverse Effect. Neither the Guarantor nor any ERISA Affiliate has incurred

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any liability pursuant to Title I or IV of ERISA or the penalty or excise tax provisions of the Code relating to employee benefit plans (as defined in Section 3 of ERISA), and no event, transaction or condition has occurred or exists that could reasonably be expected to result in the incurrence of any such liability by the Guarantor or any ERISA Affiliate, or in the imposition of any Lien on any of the rights, properties or assets of the Guarantor or any ERISA Affiliate, in either case pursuant to Title I or IV of ERISA or to such penalty or excise tax provisions or to Section 401(a)(29) or 412 of the Code or Section 4068 of ERISA, other than such liabilities or Liens as would not be individually or in the aggregate Material.

(b)    The present value of the aggregate benefit liabilities under each of the Plans (other than Multiemployer Plans), determined as of the end of such Plan’s most recently ended plan year on the basis of the actuarial assumptions specified for funding purposes in such Plan’s most recent actuarial valuation report, did not exceed the aggregate current value of the assets of such Plan allocable to such benefit liabilities. The term “benefit liabilities” has the meaning specified in Section 4001 of ERISA and the terms “current value” and “present value” have the meaning specified in Section 3 of ERISA.

(c)    The Guarantor and its ERISA Affiliates have not incurred withdrawal liabilities (and are not subject to contingent withdrawal liabilities) under Section 4201 or 4204 of ERISA in respect of Multiemployer Plans that individually or in the aggregate are Material.

(d)    The expected post retirement benefit obligation (determined as of the last day of the Guarantor’s most recently ended Fiscal Year in accordance with Financial Accounting Standards Board Statement No. 106, without regard to liabilities attributable to continuation coverage mandated by Section 4980B of the Code) of the Guarantor and its Subsidiaries is not Material.

(e)    The execution and delivery of this Guaranty will not involve any transaction that is subject to the prohibitions of Section 406(a)(i) of ERISA or in connection with which a tax could be imposed pursuant to Section 4975(c)(1)(A)-(D) of the Code. The representation by the Guarantor in the first sentence of this Section 5.12(e) is made in reliance upon and subject to the accuracy of your representation in Section 6.2 of the Note Purchase Agreement as to the sources of the funds used to pay the purchase price of the Designated CFLP Notes to be purchased by such Purchaser.

Section 5.13.    Private Offering by the Guarantor .  Neither the Guarantor nor anyone acting on its behalf has offered the Notes, this Guaranty or any similar Securities for sale to, or solicited any offer to buy any of the same from, or otherwise approached or negotiated in respect thereof with, any Person other than the Purchasers, each of which has been offered the Notes at a private sale for investment. Neither the Guarantor nor anyone acting on its behalf has taken, or will take, any action that would subject the issuance or sale of the Notes to the registration requirements of Section 5 of the Securities Act or to the registration requirements of any securities or blue sky laws of any applicable jurisdiction.

Section 5.14.    Margin Regulations.   Margin stock does not constitute more than 2% of the value of the consolidated assets of the Guarantor and its Subsidiaries and the Guarantor does not have any present intention that margin stock will constitute more than 2% of the value of such

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assets. As used in this Section, the terms “margin stock” and “purpose of buying or carrying” shall have the meanings assigned to them in said Regulation U.

Section 5.15.    Existing Debt; Future Liens .  (a)  Schedule 5.15 sets forth a complete and correct list of all outstanding Debt of the Guarantor and its Subsidiaries as of March 28, 2008 (including a description of the obligors and obligees, principal amount outstanding and collateral therefor, if any, and Guaranty thereof, if any), since which date there has been no Material change in the amounts, interest rates, sinking funds, installment payments or maturities of the Debt of the Guarantor or its Subsidiaries. Neither the Guarantor nor any Subsidiary is in default and no waiver of default is currently in effect, in the payment of any principal or interest on any Debt of the Guarantor or such Subsidiary and no event or condition exists with respect to any Debt of the Guarantor or any Subsidiary that would permit (or that with notice or the lapse of time, or both, would permit) one or more Persons to cause such Debt to become due and payable before its stated maturity or before its regularly scheduled dates of payment.

(b)    Except as disclosed in Schedule 5.15 , neither the Guarantor nor any Subsidiary has agreed or consented to cause or permit in the future (upon the happening of a contingency or otherwise) any of its property, whether now owned or hereafter acquired, to be subject to a Lien not permitted by Section 8.3 .

(c)    Neither the Guarantor nor any Subsidiary is a party to, or otherwise subject to any provision contained in, any instrument evidencing Debt of the Guarantor or such Subsidiary, any agreement relating thereto or any other agreement (including, but not limited to, its charter or other organizational document) which limits the amount of, or otherwise imposes restrictions on the incurring of, Debt of the Guarantor or any Subsidiary, except as specifically indicated in Schedule 5.15 .

Section 5.16.    Foreign Assets Control Regulations, Etc .  (a) Neither the sale of the Notes nor the use of the proceeds thereof will violate the Trading with the Enemy Act, as amended, or any of the foreign assets control regulations of the United States Treasury Department (31 CFR, Subtitle B, Chapter V, as amended) or any enabling legislation or executive order relating thereto.

(b)    Neither the Guarantor nor any Subsidiary (i) is, or will become, a Person described or designated in the Specially Designated Nationals and Blocked Persons List of the Office of Foreign Assets Control or in Section 1 of the Anti-Terrorism Order or (ii) engages or will engage in any dealings or transactions, or is or will be otherwise associated, with any such Person. The Guarantor and its Subsidiaries are in compliance, in all material respects, with the USA Patriot Act.

(c)    No part of the proceeds, if any, from the sale of the Notes will be used, directly or indirectly, for any payments to any governmental official or employee, political party, official of a political party, candidate for political office, or anyone else acting in an official capacity, in order to obtain, retain or direct business or obtain any improper advantage, in violation of the United States Foreign Corrupt Practices Act of 1977, as amended, assuming in all cases that such Act applies to the Guarantor.

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Section 5.17.    Status under Certain Statutes .  Neither the Guarantor nor any Subsidiary is subject to regulation under the Investment Guarantor Act of 1940, as amended, the ICC Termination Act of 1995, as amended, or the Federal Power Act, as amended.

Section 5.18.    Notes Rank Pari Passu .  The obligations of the Guarantor under this Guaranty rank at least pari passu in right of payment with all other unsecured Senior Debt (actual or contingent) of the Guarantor, including, without limitation, all unsecured Senior Debt of the Guarantor described in Schedule 5.15 hereto.

Section 5.19.    Environmental Matters .  (a) Neither the Guarantor nor any Subsidiary has knowledge of any claim or has received any notice of any claim, and no proceeding has been instituted raising any claim against the Guarantor or any of its Subsidiaries or any of their respective real properties now or formerly owned, leased or operated by any of them or other assets, alleging any damage to the environment or violation of any Environmental Laws, except, in each case, such as could not reasonably be expected to result in a Material Adverse Effect.

(b)    Neither the Guarantor nor any Subsidiary has knowledge of any facts which would give rise to any claim, public or private, of violation of Environmental Laws or damage to the environment emanating from, occurring on or in any way related to real properties now or formerly owned, leased or operated by any of them or to other assets or their use, except, in each case, such as could not reasonably be expected to result in a Material Adverse Effect.

(c)    Neither the Guarantor nor any Subsidiary has stored any Hazardous Materials on real properties now or formerly owned, leased or operated by any of them or has disposed of any Hazardous Materials in a manner contrary to any Environmental Laws in each case in any manner that could reasonably be expected to result in a Material Adverse Effect.

(d)    All buildings on all real properties now owned, leased or operated by the Guarantor or any Subsidiary are in compliance with applicable Environmental Laws, except where failure to comply could not reasonably be expected to result in a Material Adverse Effect.

S ECTION  6.        I NFORMATION AS TO THE G UARANTOR .

Section 6.1.    Financial and Business Information .  The Guarantor shall deliver to each holder of Notes that is an Institutional Investor:

(a)     Quarterly Statements — within 60 days after the end of each Fiscal Quarter in each Fiscal Year of the Guarantor (other than the last Fiscal Quarter of each such Fiscal Year), duplicate copies of:

(i)    an unaudited consolidated balance sheet of the Guarantor and its Subsidiaries as at the end of such quarter, and

(ii)    unaudited consolidated statements of income, changes in partners’ capital and cash flows of the Guarantor and its Subsidiaries for such quarter,

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setting forth in each case in comparative form the figures for the corresponding periods in the previous Fiscal Year, all in reasonable detail, prepared in accordance with GAAP applicable to quarterly financial statements generally, and certified by a Senior Financial Officer as fairly presenting, in all material respects, the financial position of the companies being reported on and their results of operations and cash flows, subject to changes resulting from year-end adjustments;

(b)     Annual Statements — within 90 days after the end of each Fiscal Year of the Guarantor, duplicate copies of,

(i)    a consolidated balance sheet of the Guarantor and its Subsidiaries, as at the end of such year, and

(ii)    consolidated statements of income, changes in partners’ capital and cash flows of the Guarantor and its Subsidiaries, for such year,

prepared in accordance with GAAP, and accompanied by:

(1)    an opinion thereon of independent public auditors of recognized national standing, which opinion shall state that such financial statements present fairly, in all material respects, the financial position of the companies being reported upon and their results of operations and cash flows and have been prepared in conformity with GAAP, and that the examination of such auditors in connection with such financial statements has been made in accordance with generally accepted auditing standards, and that such audit provides a reasonable basis for such opinion in the circumstances,

(2)    a report of such auditors stating that they have reviewed Section 8 of this Guaranty and the associated definitions in Schedule B to the Note Purchase Agreement and stating further whether, in making their audit, they have become aware of any condition or event that then constitutes a Default or an Event of Default, and, if they are aware that any such condition or event then exists, specifying the nature and period of the existence thereof (it being understood that such certificate shall be limited to the items that independent certified public auditors customarily cover in such certificates pursuant to the professional standards and customs in their profession); and

(3)    an unaudited consolidated balance sheet of the Guarantor and its Subsidiaries as at the end of such year, and an unaudited consolidated statement of income, changes in partners’ capital and cash flows of the Guarantor and its Subsidiaries for such year, setting forth in each case in comparative form the figures for the previous Fiscal Year, all in reasonable detail, prepared in accordance with GAAP applicable to such annual financial statements generally, and certified by a Senior

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Financial Officer as fairly presenting, in all material respects, the financial position of the companies being reported on and their results of operations and cash flows;

(c)     SEC and Other Reports — promptly upon their becoming available, one copy of (i) each financial statement, report, notice or proxy statement sent by the Guarantor or any Subsidiary to its principal lending banks as a whole, if any, (excluding information sent to such banks in the ordinary course of administration of a bank facility, such as information relating to pricing and borrowing availability or to its public Securities holders generally) and (ii) each regular or periodic report, each registration statement (without exhibits except as expressly requested by such holder), and each prospectus and all amendments thereto publicly filed by the Guarantor or any Subsidiary with the SEC or FINRA and of all press releases and other statements made available generally by the Guarantor or any Subsidiary to the public concerning developments that are Material;

(d)    [Reserved];

(e)     Notice    of Default or Event of Default — promptly, and in any event within five Business Days after a Responsible Officer becoming aware of the existence of any Default or Event of Default or that any Person has given any notice or taken any action with respect to a claimed default hereunder or that any Person has given any notice or taken any action with respect to a claimed default of the type referred to in Section 11(f) of the Note Purchase Agreement, a written notice specifying the nature and period of existence thereof and what action the Guarantor is taking or proposes to take with respect thereto;

(f)     ERISA Matters — promptly, and in any event within five Business Days after a Responsible Officer becoming aware of any of the following, a written notice setting forth the nature thereof and the action, if any, that the Guarantor or an ERISA Affiliate proposes to take with respect thereto:

(i)    with respect to any Plan, any reportable event, as defined in Section 4043(c) of ERISA and the regulations thereunder, for which notice thereof has not been waived pursuant to such regulations as in effect on the date hereof; or

(ii)    the taking by the PBGC of steps to institute, or the threatening by the PBGC of the institution of, proceedings under Section 4042 of ERISA for the termination of, or the appointment of a trustee to administer, any Plan, or the receipt by the Guarantor or any ERISA Affiliate of a notice from a Multiemployer Plan that such action has been taken by the PBGC with respect to such Multiemployer Plan; or

(iii)    any event, transaction or condition that could result in the incurrence of any liability by the Guarantor or any ERISA Affiliate pursuant to

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Title I or IV of ERISA or the penalty or excise tax provisions of the Code relating to employee benefit plans, or in the imposition of any Lien on any of the rights, properties or assets of the Guarantor or any ERISA Affiliate pursuant to Title I or IV of ERISA or such penalty or excise tax provisions, if such liability or Lien, taken together with any other such liabilities or Liens then existing, could reasonably be expected to have a Material Adverse Effect;

(g)     Notices from Governmental Authority — promptly, and in any event within 30 days of receipt thereof, copies of any notice to the Guarantor or any Subsidiary from any federal or state Governmental Authority relating to any order, ruling, statute or other law or regulation that could reasonably be expected to have a Material Adverse Effect; and

(h)     Requested Information — with reasonable promptness, such other data and information relating to the business, operations, affairs, financial condition, assets or properties of the Guarantor or any of its Subsidiaries or relating to the ability of the Guarantor to perform its obligations hereunder and under the Notes as from time to time may be reasonably requested by any such holder of Notes.

Section 6.2.    Officer’s Certificate .  Each set of financial statements delivered to a holder of Notes pursuant to Section 6.1(a) or Section 6.1(b) hereof shall be accompanied by a certificate of a Senior Financial Officer setting forth:

(a)     Covenant Compliance — the information (including, where appropriate, detailed calculations) required in order to establish whether the Guarantor was in compliance with the requirements of Section 8.1 through Section 8.5 , inclusive, during the applicable Fiscal Quarter covered by such financial statements, or in the case of the financial statements for a Fiscal Year, during the fourth Fiscal Quarter of such Fiscal Year (including with respect to each such Section, where applicable, the calculations of the maximum or minimum amount, ratio or percentage, as the case may be, permissible under the terms of such Sections, and the calculation of the amount, ratio or percentage then in existence, and in the case of Section 8.2 , whether and to what extent and degree Consolidated Debt exceeded 55% of Consolidated Capitalization at any time during the applicable Fiscal Quarter to which such compliance certificate relates, or in the case of the compliance certificate for a Fiscal Year, during the fourth Fiscal Quarter of such Fiscal Year, the period or periods of time during which Consolidated Debt so exceeded Consolidated Capitalization and, as applicable, when a related Interest Rate Adjustment Period begins, the amount of interest payable on the Notes constituting the Interest Rate Adjustment and the date on which such amount of interest is payable or was paid); and

(b)     Event of Default — a statement that such Senior Financial Officer has reviewed the relevant terms hereof and has made, or caused to be made, under his or her supervision, a review of the transactions and conditions of the Guarantor and its Subsidiaries from the beginning of the Fiscal Quarter or Fiscal Year covered by the statements then being furnished to the date of the certificate and that such review shall not have disclosed the existence during such period of any condition or event that

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constitutes a Default or an Event of Default or, if any such condition or event existed or exists (including, without limitation, any such event or condition resulting from the failure of the Guarantor or any Subsidiary to comply with any Environmental Law), specifying the nature and period of existence thereof and what action the Guarantor shall have taken or proposes to take with respect thereto.

Section 6.3.    Visitation .  The Guarantor shall permit the representatives of each holder of Notes that is an Institutional Investor:

(a)     No Default — if no Default or Event of Default then exists, at the expense of such holder and upon reasonable prior notice to the Guarantor, to visit the principal executive office of the Guarantor, to discuss the affairs, finances and accounts of the Guarantor and its Subsidiaries with the Guarantor’s officers, and (with the opportunity to participate and consent of the Guarantor, which consent will not be unreasonably withheld) its independent public auditors, and (with the consent of the Guarantor, which consent will not be unreasonably withheld) to visit the other offices and properties of the Guarantor and each Subsidiary, all at such reasonable times and as often as may be reasonably requested in writing; and

(b)     Default — if a Default or Event of Default then exists, at the expense of the Guarantor, to visit and inspect any of the offices or properties of the Guarantor or any Subsidiary, to examine all their respective books of account, records, reports and other papers, to make copies and extracts therefrom, and to discuss their respective affairs, finances and accounts with their respective officers and independent public auditors (and by this provision the Guarantor authorizes said auditors to discuss the affairs, finances and accounts of the Guarantor and its Subsidiaries), all at such times and as often as may be reasonably requested.

S ECTION  7.        A FFIRMATIVE C OVENANTS .

The Guarantor covenants that so long as any of the Notes are outstanding:

Section 7.1.    Compliance with Law .  The Guarantor will, and will cause each of its Subsidiaries to, comply with all laws, ordinances or governmental rules or regulations to which each of them is subject, including, without limitation, ERISA, the USA Patriot Act and Environmental Laws, and will obtain and maintain in effect all licenses, certificates, permits, franchises and other governmental authorizations necessary to the ownership of their respective properties or to the conduct of their respective businesses, in each case to the extent necessary to ensure that non-compliance with such laws, ordinances or governmental rules or regulations or failures to obtain or maintain in effect such licenses, certificates, permits, franchises and other governmental authorizations could not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect.

Section 7.2.    Insurance .  The Guarantor will, and will cause each of its Subsidiaries to, maintain, with financially sound and reputable insurers, insurance with respect to their respective properties and businesses against such casualties and contingencies, of such types, on such terms

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and in such amounts (including deductibles, co-insurance and self-insurance, if adequate reserves are maintained with respect thereto) as is customary in the case of entities of established reputations engaged in the same or a similar business and similarly situated and the failure of which to so maintain would have a Material Adverse Effect.

Section 7.3.    Maintenance of Properties .  The Guarantor will, and will cause each of its Subsidiaries to, maintain and keep, or cause to be maintained and kept, their respective properties