FIRST SUPPLEMENTAL INDENTURE Dated as of August 20, 2009 Supplementing that Certain

Exhibit 4.2

EXECUTION COPY

FIRST SUPPLEMENTAL INDENTURE

Dated as of August 20, 2009

Supplementing that Certain

INDENTURE

Dated as of August 20, 2009

Among

BLACKSTONE HOLDINGS FINANCE CO. L.L.C.,

THE GUARANTOR PARTIES HERETO

and

THE BANK OF NEW YORK MELLON,

as Trustee

6.625% Senior Notes due 2019

TABLE OF CONTENTS

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This First Supplemental Indenture, dated as of August 20, 2009 (the “ First Supplemental Indenture ”), among Blackstone Holdings Finance Co. L.L.C., a limited liability company duly organized and existing under the laws of the State of Delaware, having its principal office at 345 Park Avenue, New York, New York 10154 (the “ Company ”), the Guarantors party hereto and The Bank of New York Mellon, a New York banking corporation, as Trustee under the Base Indenture (as hereinafter defined) and hereunder (the “ Trustee ”), supplements that certain Indenture, dated as of August 20, 2009, among the Company, the Guarantors named therein and the Trustee (the “ Base Indenture ” and subject to Section 1.3 hereof, together with this First Supplemental Indenture, the “ Indenture ”).

RECITALS OF THE COMPANY

The Company and the Guarantors have heretofore executed and delivered to the Trustee the Base Indenture providing for the issuance from time to time of one or more series of the Company’s senior unsecured debt securities (herein and in the Base Indenture called the “Securities”), the forms and terms of which are to be determined as set forth in Sections 201 and 301 of the Base Indenture, and the Guarantees thereof by the Guarantors; and

Section 901 of the Base Indenture provides, among other things, that the Company, the Guarantors and the Trustee may enter into indentures supplemental to the Base Indenture for, among other things, the purposes of (a) establishing the form or terms of Securities of any series as permitted by Sections 201 and 301 of the Base Indenture and (b) adding to or changing any of the provisions to the Base Indenture in certain circumstances;

The Company desires to create a series of Securities designated as its “6.625% Senior Notes due 2019” pursuant to the terms of this First Supplemental Indenture.

The Company has duly authorized the execution and delivery of this First Supplemental Indenture and the Notes to be issued from time to time, as provided for in the Indenture.

Each Guarantor has duly authorized its Guarantee of the Notes and to provide therefor each Guarantor has duly authorized the execution and delivery of this First Supplemental Indenture.

All things necessary have been done to make this First Supplemental Indenture a valid and legally binding agreement of the Company, in accordance with its terms and to make the Notes, when executed by the Company and authenticated and delivered and under the Indenture and duly issued by the Company, the valid and legally binding obligations of the Company.

All things necessary have been done to make the Guarantees, upon execution and delivery of this First Supplemental Indenture, the valid and legally binding obligations of each Guarantor and to make this First Supplemental Indenture a valid and legally binding agreement of each Guarantor, in accordance with its terms.

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ARTICLE I

Issuance of Securities

SECTION 1.1. Issuance of Notes; Principal Amount; Maturity; Title.

(1) On August 20, 2009, the Company shall issue and deliver to the Trustee, and the Trustee shall authenticate, the Initial Notes substantially in the form set forth in Section 3.2 below, in each case with such appropriate insertions, omissions, substitutions and other variations as are required or permitted by the Base Indenture and this First Supplemental Indenture, and with such letters, numbers, or other marks of identification and such legends or endorsements placed thereon as may be required to comply with applicable tax laws or the rules of any securities exchange or Depositary therefor or as may, consistently herewith, be determined by the Officer executing such Notes, as evidenced by the execution of such Notes.

(2) The Initial Notes to be issued pursuant to the Indenture shall be issued in the aggregate principal amount of $600,000,000 and shall mature on August 15, 2019, unless the Notes are redeemed prior to that date as described in Section 5.1. The aggregate principal amount of Initial Notes Outstanding at any time may not exceed $600,000,000, except for Notes issued, authenticated and delivered upon registration of transfer of, or in exchange for, or in lieu of, other Notes of the series pursuant to Sections 304, 305, 306, 906 or 1107 of the Base Indenture and except for any Notes which, pursuant to Section 303 of the Base Indenture, are deemed never to have been authenticated and delivered. The Company may without the consent of the Holders, issue additional Notes hereunder as part of the same series and on the same terms and conditions (and having the same Guarantors) and with the same CUSIP numbers as the Initial Notes, but may be offered at a different offering price or have a different issue date, initial interest accrual or initial interest payment date (“ Additional Notes ”); provided that if any Additional Notes are issued at a price that causes such Additional Notes to have “original issue discount” within the meaning of Section 1273 of the United States Internal Revenue Code of 1986, as amended, and regulations of the United States Department of Treasury thereunder (the “ Code ”), such Additional Notes shall not have the same CUSIP number as the Initial Notes.

(3) The Notes shall be issued only in fully registered form without coupons in minimum denominations of $2,000 and any integral multiple of $1,000 in excess thereof.

(4) Pursuant to the terms hereof and Sections 201 and 301 of the Base Indenture, the Company hereby creates a series of Securities designated as the “6.625% Senior Notes due 2019” of the Company (as amended or supplemented from time to time, that are issued under the Indenture, including both the Initial Notes and the Additional Notes, if any, the “ Notes ”), which Notes shall be deemed “Securities” for all purposes under the Base Indenture.

SECTION 1.2. Interest.

(1) Interest on a Note will accrue at the per annum rate of 6.625% (the “ Note Interest Rate ”), from and including the date specified on the face of such Note to, but excluding, the date on which the principal thereof is paid, deemed paid, or made available for payment and, in each case, will be paid on the basis of a 360-day year comprised of twelve 30-day months.

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(2) The Company shall pay interest on the Notes semi-annually in arrears on February 15 and August 15 of each year (each, an “ Interest Payment Date ”), commencing February 15, 2010.

(3) Interest shall be paid on each Interest Payment Date to the registered Holders of the Notes after the close of business on the Regular Record Date.

(4) Amounts due on the Stated Maturity or earlier Redemption Date of the Notes will be payable at the Corporate Trust Office. The Company shall make payments of principal, premium, if any, and interest or the Repurchase Price in connection with a Change of Control Repurchase Event in respect of the Notes in book-entry form to DTC in immediately available funds, while disbursement of such payments to owners of beneficial interests in Notes in book-entry form will be made in accordance with the procedures of DTC and its participants in effect from time to time. The Company may at any time designate additional Paying Agents or rescind the designation of any Paying Agent or approve a change in the office through which any Paying Agent acts, except that the Company shall be required to maintain a Paying Agent in each Place of Payment for the Notes. Neither the Company nor the Trustee shall impose any service charge for any transfer or exchange of a Note. However, the Company may require Holders of the Notes to pay any taxes or other governmental charges in connection with a transfer or exchange of Notes.

(5) If any Interest Payment Date, Stated Maturity, or earlier Redemption Date or Repurchase Price Payment Date falls on a day that is not a Business Day in The City of New York, the Company shall make the required payment of principal, premium, if any, and/or interest or Repurchase Price in connection with a Change of Control Repurchase Event on the next succeeding Business Day as if it were made on the date payment was due, and no interest will accrue on the amount so payable for the period from and after that Interest Payment Date, Stated Maturity or earlier Redemption Date or Repurchase Price Payment Date, as the case may be, to such next succeeding Business Day.

SECTION 1.3. Relationship with Base Indenture.

The terms and provisions contained in the Base Indenture will constitute, and are hereby expressly made, a part of this First Supplemental Indenture. However, to the extent any provision of the Base Indenture conflicts with the express provisions of this First Supplemental Indenture, the provisions of this First Supplemental Indenture will govern and be controlling.

ARTICLE II

Definitions and Other Provisions of General Application

SECTION 2.1. Definitions.

For all purposes of this First Supplemental Indenture (except as herein otherwise expressly provided or unless the context of this First Supplemental Indenture otherwise requires):

(1) any reference to an “Article” or a “Section” refers to an Article or a Section, as the case may be, of this First Supplemental Indenture;

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(2) the words “herein,” “hereof” and “hereunder” and other words of similar import refer to this First Supplemental Indenture as a whole and not to any particular Article, Section or other subdivision;

(3) “including” means including without limitation;

(4) unless otherwise provided, references to agreements and other instruments shall be deemed to include all amendments and other modifications to such agreements and instruments, but only to the extent such amendments and other modifications are not prohibited by the terms of this Indenture.

The terms defined in this Section 2.1 (except as herein otherwise expressly provided or unless the context of this First Supplemental Indenture otherwise requires) for all purposes of this First Supplemental Indenture and of any indenture supplemental hereto have the respective meanings specified in this Section 2.1. All other terms used in this First Supplemental Indenture that are defined in the Base Indenture, either directly or by reference therein (except as herein otherwise expressly provided or unless the context of this First Supplemental Indenture otherwise requires), have the respective meanings assigned to such terms in the Base Indenture, as in force at the date of this First Supplemental Indenture as originally executed; provided that any term that is defined in both the Base Indenture and this First Supplemental Indenture shall have the meaning assigned to such term in this First Supplemental Indenture.

“ Additional Notes ” has the meaning specified in Section 1.1(2).

“ Applicable Procedures ” means, with respect to any transfer or transaction involving a Global Security or beneficial interest therein, the rules and procedures of DTC, Euroclear and Clearstream, in each case to the extent applicable to such transaction and as in effect from time to time.

“ Below Investment Grade Rating Event ” means the rating on the Notes is lowered in respect of a Change of Control and the Notes are rated below Investment Grade by both Rating Agencies on any date from the date of the public notice of an arrangement that could result in a Change of Control until the end of the 60-day period following public notice of the occurrence of a Change of Control (which period shall be extended until the ratings are announced if during such 60 day period the rating of the Notes is under publicly announced consideration for possible downgrade by either of the Rating Agencies); provided that a Below Investment Grade Rating Event otherwise arising by virtue of a particular reduction in rating shall not be deemed to have occurred in respect of a particular Change of Control (and thus shall not be deemed a Below Investment Grade Rating Event for purposes of the definition of Change of Control Repurchase Event hereunder) if the Rating Agencies making the reduction in rating to which this definition would otherwise apply do not announce or publicly confirm or inform the Company in writing at its request that the reduction was the result, in whole or in part, of any event or circumstance comprised of or arising as a result of, or in respect of, the applicable Change of Control (whether or not the applicable Change of Control shall have occurred at the time of the Below Investment Grade Rating Event).

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“ Change of Control ” means the occurrence of the following:

“ Change of Control Offer ” has the meaning specified in Section 6.2(1).

“ Change of Control Repurchase Event ” means the occurrence of a Change of Control and a Below Investment Grade Rating Event.

“ Clearstream ” means Clearstream Banking, S.A.

“ Code ” has the meaning specified in Section 1.1(2).

“ Commission ” means the Securities and Exchange Commission or any successor entity.

“ Comparable Treasury Issue ” means the United States Treasury security or securities selected by an Independent Investment Banker as having an actual or interpolated maturity comparable to the remaining term of the Notes to be redeemed that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of a comparable maturity to the remaining term of such Notes.

“ Comparable Treasury Price ” means, with respect to any Redemption Date, the average of the Reference Treasury Dealer Quotations for such Redemption Date or, if the Trustee obtains only one Reference Treasury Dealer Quotation, such Reference Treasury Dealer Quotation.

“ Continuing Blackstone Entity ” means any entity that, immediately prior to and immediately following any relevant date of determination, is directly or indirectly controlled by one or more senior managing directors or other personnel of the Partnership who, as of any date of determination (i) each have devoted substantially all of his or her business and professional time to the activities of the Credit Parties and/or their Subsidiaries during the 12-month period immediately preceding such date and (ii) directly or indirectly control a majority of the general partner interests (or other similar interests) in Partnership or any successor entity.

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“ Covenant Defeasance ” has the meaning specified in Section 8.1.

“ DTC ” means The Depository Trust Company, a New York corporation.

“ Euroclear ” means Euroclear Bank, S.A./N.V., as operator of the Euroclear system.

“ Event of Default ” has the meaning specified in Section 4.1.

“ Fitch ” means Fitch Ratings Inc. or any successor thereto.

“ Independent Investment Banker ” means one of the Reference Treasury Dealers appointed by the Trustee after consultation with the Company.

“ Initial Notes ” means Notes in an aggregate principal amount of up to $600,000,000 initially issued under this First Supplemental Indenture in accordance with Section 1.1(2).

“ Interest Payment Date ” has the meaning specified in Section 1.2(2).

“ Investment Grade ” means a rating of BBB- or better by Fitch (or its equivalent under any successor rating categories of Fitch) and BBB- or better by S&P (or its equivalent under any successor rating categories of S&P) (or, in each case, if such Rating Agency ceases to rate the Notes of either series for reasons outside of the Company’s control, the equivalent investment grade credit rating from any Rating Agency selected by the Company as a replacement Rating Agency).

“ Majority Economic Interest ” means any right or entitlement to receive more than 50% of the equity distributions or partner allocations (whether such right or entitlement results from the ownership of partner or other equity interests, securities, instruments or agreements of any kind) made to all holders of partner or other equity interests in the Credit Group (other than entities within the Credit Group).

“ Maturity Date ” means August 15, 2019.

“ Note Interest Rate ” has the meaning specified in Section 1.2(1).

“ Notes ” has the meaning specified in Section 1.1(4).

“ Permitted Liens ” means (a) liens on voting stock or profit participating equity interests of any Subsidiary existing at the time such entity becomes a direct or indirect Subsidiary of the Partnership or is merged into a direct or indirect Subsidiary of the Partnership ( provided such liens are not created or incurred in connection with such transaction and do not extend to any other Subsidiary), and (b) statutory liens, liens for taxes or assessments or governmental liens not yet due or delinquent or which can be paid without penalty or are being contested in good faith and (c) other liens of a similar nature as those described above.

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“ Rating Agency ” means:

“ Reference Treasury Dealer ” means each of Morgan Stanley & Co. Incorporated and Citigroup Global Markets Inc. or their respective affiliates which are primary U.S. Government securities dealers, and their respective successors; provided that if Morgan Stanley & Co. or Citigroup Global Markets Inc. or their respective affiliates shall cease to be a primary U.S. Government securities dealer in The City of New York (a “Primary Treasury Dealer”), the Company shall substitute therefor another Primary Treasury Dealer.

“ Reference Treasury Dealer Quotations ” means, with respect to each Reference Treasury Dealer and any Redemption Date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by such Reference Treasury Dealer at 3:30 p.m. New York time on the third business day preceding such Redemption Date.

“ Registrar ” means the Security Registrar for the Notes, which shall initially be The Bank of New York Mellon, or any successor entity thereof, subject to replacement as set forth in the Base Indenture.

“ Regular Record Date ” for interest payable in respect of any Note on any Interest Payment Date means the day that is 15 days prior to the relevant Interest Payment Date (whether or not a Business Day).

“ Repurchase Price ” has the meaning specified in Section 6.2(1).

“ Repurchase Price Payment Date ” has the meaning specified in Section 6.2(2)(iii).

“ S&P ” means Standard & Poor’s Financial Services LLC, a subsidiary of The McGraw-Hill Companies, Inc., or any successor thereto.

“ Treasury Rate ” means, with respect to any Redemption Date, the rate per annum equal to the semiannual equivalent yield to maturity or interpolated (on a day count basis) of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such Redemption Date.

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ARTICLE III

Security Forms

SECTION 3.1. Form Generally.

(1) The Notes shall be in substantially the form set forth in Section 3.2 of this Article III, with such appropriate insertions, omissions, substitutions and other variations as are required or permitted by the Base Indenture and this First Supplemental Indenture, and may have such letters, numbers or other marks of identification and such legends or endorsements placed thereon as may be required to comply with applicable tax laws or the rules of any securities exchange or Depositary therefore or as may, consistent herewith, be determined by the Officer executing such Notes, as evidenced by the execution thereof. All Notes shall be in fully registered form.

(2) The Notes shall be printed, lithographed or engraved on steel engraved borders or may be produced in any other manner, all as determined by the Officer of the Company executing such Notes, as evidenced by the execution of such Notes.

(3) Upon their original issuance, the Notes shall be issued in the form of one or more Global Securities in definitive, fully registered form without interest coupons. Each such Global Security shall be duly executed by the Company, authenticated and delivered by the Trustee and shall be registered in the name of DTC, as Depositary, or its nominee, and deposited with the Trustee, as custodian for DTC. Beneficial interests in the Global Securities will be shown on, and transfers will only be made through, the records maintained by DTC and its participants, including Clearstream and the Euroclear System.

SECTION 3.2. Form of Note.

[FORM OF FACE OF NOTE]

[THE FOLLOWING LEGEND SHALL APPEAR ON THE FACE OF EACH GLOBAL SECURITY SOLD PURSUANT TO RULE 144A UNDER THE SECURITIES ACT:

THIS SECURITY (INCLUDING THE RELATED GUARANTEES) HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), OR THE SECURITIES LAWS OF ANY STATE OR OTHER JURISDICTION. NEITHER THIS SECURITY NOR ANY INTEREST OR PARTICIPATION HEREIN MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, ENCUMBERED OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS SUCH TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, SUCH REGISTRATION. THE HOLDER OF THIS SECURITY, BY ITS ACCEPTANCE HEREOF, AGREES ON ITS OWN BEHALF AND ON BEHALF OF ANY INVESTOR ACCOUNT FOR WHICH IT HAS PURCHASED SECURITIES, TO OFFER, SELL OR OTHERWISE TRANSFER SUCH SECURITY, PRIOR TO THE DATE (THE “RESALE RESTRICTION

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TERMINATION DATE”) THAT IS ONE YEAR AFTER THE LATER OF THE ISSUE DATE HEREOF OR ANY OTHER ISSUE DATE IN RESPECT OF A FURTHER ISSUANCE OF SECURITIES OF THE SAME SERIES AND THE LAST DATE ON WHICH BLACKSTONE HOLDINGS FINANCE CO. L.L.C. OR ANY AFFILIATE OF BLACKSTONE HOLDINGS FINANCE CO. L.L.C. WAS THE OWNER OF THIS SECURITY (OR ANY PREDECESSOR OF SUCH SECURITY), ONLY (A) TO BLACKSTONE HOLDINGS FINANCE CO. L.L.C. OR THE BLACKSTONE GROUP L.P., BLACKSTONE HOLDINGS I L.P., BLACKSTONE HOLDINGS II L.P., BLACKSTONE HOLDINGS III L.P. OR BLACKSTONE HOLDING IV L.P. OR ANY SUBSIDIARY THEREOF, (B) PURSUANT TO A REGISTRATION STATEMENT THAT HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT, (C) FOR SO LONG AS THE SECURITIES ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT (“RULE 144A”), TO A PERSON IT REASONABLY BELIEVES IS A “QUALIFIED INSTITUTIONAL BUYER” AS DEFINED IN RULE 144A THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 144A, (D) PURSUANT TO OFFERS AND SALES TO NON-U.S. PERSONS THAT OCCUR OUTSIDE THE UNITED STATES WITHIN THE MEANING OF REGULATION S UNDER THE SECURITIES ACT, (E) TO AN INSTITUTIONAL “ACCREDITED INVESTOR” WITHIN THE MEANING OF RULE 501(a)(1), (2), (3) OR (7) UNDER THE SECURITIES ACT THAT IS NOT A QUALIFIED INSTITUTIONAL BUYER AND THAT IS PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF ANOTHER INSTITUTIONAL ACCREDITED INVESTOR, IN EACH CASE IN A MINIMUM PRINCIPAL AMOUNT OF THE SECURITIES OF $250,000, FOR INVESTMENT PURPOSES AND NOT WITH A VIEW TO OR FOR OFFER OR SALE IN CONNECTION WITH ANY DISTRIBUTION IN VIOLATION OF THE SECURITIES ACT OR (F) PURSUANT TO ANOTHER AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT, SUBJECT TO BLACKSTONE HOLDINGS FINANCE CO. L.L.C.’S AND THE TRUSTEE’S RIGHT PRIOR TO ANY SUCH OFFER, SALE OR TRANSFER