Orbital ATK,Inc. (NYSE:OA) Files An 8-K Changes in Registrant’s Certifying Accountant

Item 4.01. Change in Registrants Certifying Accountant.

(a)Dismissal of Independent Registered Public Accountant

On May1, 2017, the Audit Committee (the Audit Committee) of the
Board of Directors of Orbital ATK,Inc. (the Company) dismissed
PricewaterhouseCoopers LLP (PwC) as the Companys independent
registered public accounting firm. PwC had been engaged on
June30, 2015 and had been the Companys independent registered
public accounting firm for the year ended December31, 2016 and
the nine-month transition period ended December31, 2015 (the 2015
transition period).

PwCs reports on the financial statements of the Company for the
year ended December31, 2016 and the 2015 transition period did
not contain any adverse opinion or a disclaimer of opinion and
were not qualified or modified as to uncertainty, audit scope, or
accounting principles.

During the period from June30, 2015 to December31, 2015, the year
ended December31, 2016 and the subsequent interim period through
May1, 2017, there were no disagreements between the Company and
PwC on any matter of accounting principles or practices,
financial statement disclosure, or auditing scope or procedures,
which disagreements, if not resolved to the satisfaction of PwC,
would have caused PwC to make reference to the subject matter of
the disagreements in connection with its report.

During the year ended December31, 2016, the 2015 transition
period and the subsequent interim period through May1, 2017,
there were reportable events within the meaning set forth in Item
304(a)(1)(v)of Regulation S-K under the Securities Act of 1933.
As disclosed in the Companys Annual Report on Form10-K for the
year ended December31, 2016 and the Companys Annual Report on
Form10-K/A for the 2015 transition period, the Company and PwC
each concluded that the Company did not maintain effective
internal control over financial reporting as of December31, 2015,
and as of December31, 2016, because of material weaknesses in our
control environment related to (i)establishing and maintaining
accounting policies and procedures related to complex
transactions, and (ii)maintaining a sufficient complement of
personnel with appropriate levels of accounting and controls
knowledge, experience, and training commensurate with the nature
and complexity of our business and contract activity. These
material weaknesses in our control environment contributed to
material weaknesses at the control activity level where the
Company (iii)did not design appropriate controls to ensure
completeness and accuracy of purchase accounting, specifically
the Company did not maintain controls over measurement period
adjustments and controls over the calculation of acquired
contracts percentage of completion used to recognize revenue
(this material weaknesses was identified in 2015 and remediated
during the quarter ended December31, 2016), and (iv)did not
maintain controls over the integration of accounting operations
of the two merged companies and over the preparation, analysis
and review of accounts of the combined business. Also, the
Company (v)did not maintain an effective control environment at
its Defense Systems Group and its Small Caliber Systems Division,
specifically the Small Caliber Systems Division did not maintain
a control environment where procedures to escalate accounting
issues to Defense Systems Group or Corporate management were
followed, which led to the suppression of information by Small
Caliber Systems Division management related to cost overruns and
the override of certain controls due to pressure to achieve cost
savings and maintain a targeted profit rate. This material
weakness in our control environment contributed to (vi)a material
weakness at the Small Caliber Systems Division, where the Small
Caliber Systems division did not design and maintain controls
related to the preparation, review and approval of costs incurred
and contract estimates used to determine revenue. The Audit
Committee has had extensive discussions with PwC regarding these
conclusions. The Company authorized PwC to fully respond to the
inquiries of the successor accountant concerning these material
weaknesses.

The Company provided PwC a copy of the above disclosures in this
Item 4.01 and requested that PwC provide the Company with a
letter addressed to the Securities and Exchange Commission
stating whether PwC agrees with the above statements made by the
Company in response to Item 304(a)of Regulation S-K. A copy of
this letter dated May5, 2017 furnished by PwC in response to that
request is filed as Exhibit16.1 to this Form8-K.

About Orbital ATK, Inc. (NYSE:OA)

Orbital ATK, Inc. is an aerospace and defense systems company and supplier of related products to the United States Government, allied nations, prime contractors and other customers. The Company’s segments include Flight Systems Group, Defense Systems Group, Space Systems Group and Corporate. Its products include launch vehicles and related propulsion systems; satellites and associated components and services; tactical missiles, subsystems and defense electronics, and precision weapons, armament systems and ammunition. The Flight Systems Group segment consists of Launch Vehicles Division, Propulsion Systems Division and Aerospace Structures Division. The Defense Systems Group segment consists of Armament Systems Division, Defense Electronic Division, Missile Products Division and Small Caliber Systems Division. The Space Systems Group consists of Commercial Satellites Division, Government Satellites Division, Space Components Division and Technical Services Division.

Orbital ATK, Inc. (NYSE:OA) Recent Trading Information

Orbital ATK, Inc. (NYSE:OA) closed its last trading session up +0.42 at 98.71 with 186,141 shares trading hands.