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): January 3, 2017

Registrant’s Telephone Number, Including Area Code: (310) 252-8100

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):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 3.02 Unregistered Sales of Equity Securities.

From November 25, 2016 to January 9, 2017, Aerojet Rocketdyne Holdings, Inc. (the “Company”) issued 4.30 million shares of the Company’s common stock, par value $0.10 (the “Common Stock”), in connection with the conversion during that period of an aggregate of $38.67 million principal amount of the Company’s 4.0625% Convertible Subordinated Debentures due 2039 (the “Debentures”), which Debentures were surrendered for conversion pursuant to the terms of the indenture governing the Debentures. The conversion rate provided under the terms of the Debentures was 111.0926 shares of Common Stock per $1,000 principal amount of the Debentures, equivalent to a conversion price of approximately $9.00 per share of Common Stock. The issuance of Common Stock was made pursuant to the exemption from the registration requirements of the Securities Act of 1933, as amended (the “Securities Act”), provided by Section 3(a)(9) of the Securities Act. As of January 9, 2017, the remaining balance of the Debentures was $2.88 million.

SIGNATURES

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.