UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): April 7, 2014

The Blackstone Group L.P.

(Exact name of Registrant as specified in its charter)

(212) 583-5000

(Registrant’s telephone number, including area code)

NOT APPLICABLE

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

On April 7, 2014, The Blackstone Group L.P. (the “Partnership”), Blackstone Holdings I L.P., Blackstone Holdings II L.P., Blackstone Holdings III L.P. and Blackstone Holdings IV L.P., each indirect subsidiaries of the Partnership (collectively with the Partnership, the “Guarantors”), and Blackstone Holdings Finance Co. L.L.C., an indirect subsidiary of the Partnership (the “Issuer”), entered into a supplemental indenture (the “Fifth Supplemental Indenture”) to the indenture previously entered into on August 20, 2009 (the “Base Indenture” and, together with the Fifth Supplemental Indenture, the “Indenture”) with The Bank of New York Mellon, as trustee (the “Trustee”), relating to the issuance by the Issuer of $500,000,000 aggregate principal amount of its 5.000% Senior Notes due 2044 (the “Notes”).

The Notes bear interest at a rate of 5.000% per annum, accruing from April 7, 2014. Interest is payable semiannually in arrears on June 15 and December 15 of each year, commencing on December 15, 2014. The Notes will mature on June 15, 2044 unless earlier redeemed or repurchased. The Notes are unsecured and unsubordinated obligations of the Issuer. The Notes will be fully and unconditionally guaranteed (the “Guarantees”), jointly and severally, by each of the Guarantors. The Guarantees are unsecured and unsubordinated obligations of the Guarantors.

The Indenture includes covenants, including limitations on the Issuer’s and the Guarantors’ ability to, subject to exceptions, incur indebtedness secured by liens on voting stock or profit participating equity interests of their subsidiaries or merge, consolidate or sell, transfer or lease assets. The Indenture also provides for events of default and further provides that the Trustee or the holders of not less than 25% in aggregate principal amount of the outstanding Notes may declare the Notes immediately due and payable upon the occurrence and during the continuance of any event of default after expiration of any applicable grace period. In the case of specified events of bankruptcy, insolvency, receivership or reorganization, the principal amount of the Notes and any accrued and unpaid interest on the Notes automatically become due and payable. All or a portion of the Notes may be redeemed at the Issuer’s option in whole or in part, at any time and from time to time, prior to their stated maturity, at the make-whole redemption price set forth in the Notes. If a change of control repurchase event occurs, the Notes are subject to repurchase by the Issuer at a repurchase price in cash equal to 101% of the aggregate principal amount of the Notes repurchased plus any accrued and unpaid interest on the Notes repurchased to, but not including, the date of repurchase.

The preceding is a summary of the terms of the Base Indenture, the Fifth Supplemental Indenture and the form of the Notes, and is qualified in its entirety by reference to the Base Indenture attached hereto as Exhibit 4.1, the Fifth Supplemental Indenture attached as Exhibit 4.2 to this report and the form of the Notes attached as Exhibit 4.3 to this report, each of which is incorporated herein by reference as though they were fully set forth herein.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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