Sec Form 4 Filing - KAHN MICHAEL A @ ORBITAL ATK, INC. - 2018-03-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person KAHN MICHAEL A 2. Issuer Name and Ticker or Trading Symbol ORBITAL ATK, INC. [ OA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) EVP, Pres Defense Sys Grp (Last) (First) (Middle) C/O ORBITAL ATK, INC., 45101 WARP DRIVE 3. Date of Earliest Transaction (MM/DD/YY) 03/01/2018 (Street) DULLES, VA20166 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Phantom Stock Units ( 1 ) ( 2 ) 03/01/2018 A 3.0686 ( 1 ) ( 1 ) Common Stock 3.0686 $ 131.96 1,268 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other KAHN MICHAEL A C/O ORBITAL ATK, INC. 45101 WARP DRIVE DULLES, VA20166 EVP, Pres Defense Sys Grp Signatures /s/ Richard N. Osborne, Attorney-in-Fact 03/19/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These securities were acquired through the deemed reinvestment of dividend equivalents in the form of additional Phantom Stock Units credited to the reporting person's account under the Issuer's Nonqualified Deferred Compensation Plan (NQDCP). The Phantom Stock Units will be settled 100% in cash following the reporting person's termination of employment or such other date specified by the reporting person. NQDCP participants may reallocate amounts between this Phantom Stock Unit investment alternative and other investment accounts during a 10-day window period each quarter. ( 2 )1-for-1.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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