X0306 4/A 2018-02-27 2018-03-01 0 0000866121 ORBITAL ATK, INC. OA 0001514429 Wolf Christine Ann C/O ORBITAL ATK, INC. 45101 WARP DRIVE DULLES VA 20166 0 1 0 0 Senior VP Human Resources Common Stock 2018-02-27 4 F 0 182 131.65 D 20710 D The Form 4 originally filed to report this withholding of shares to pay taxes applicable to the vesting of restricted stock has been amended for the purpose of clarifying this transaction was a disposition of securities and not an acquisition. 5,044 of these shares are subject to certain restrictions including possible forfeiture under Orbital ATK, Inc.'s stock incentive plans. /s/ Richard N. Osborne, Attorney-in-Fact 2018-03-01