Merger Expected to Close February 9; New Company To Begin Operations February 10

Orbital Sciences Corporation has announced that at a special meeting held Tuesday morning, the company’s stockholders voted overwhelmingly to approve the proposed merger with the Aerospace and Defense Groups of Alliant Techsystems Inc., pursuant to the definitive transaction agreement dated April 28, 2014. Approximately 99% of the votes cast at the special meeting voted in favor of the adoption of the transaction agreement, which represented approximately 85% of the total number of outstanding shares of Orbital common stock as of the December 16, 2014 record date for the special meeting.

“Today, Orbital’s stockholders endorsed the proposed merger with ATK’s Aerospace and Defense Groups by voting strongly in favor of the transaction, as did ATK shareholders at a separate special meeting also held earlier today,” said Mr. David W. Thompson, Orbital’s Chairman and Chief Executive Officer. “We are now on a clear path to completing the merger and beginning operations of Orbital ATK two weeks from today.”

Subject to the satisfaction or waiver of the remaining conditions to closing, the merger is expected to close on Monday, February 9, 2015. Assuming completion of the merger, shares of Orbital common stock are expected to be delisted after the close of trading on February 9.

As a result of the merger, each share of Orbital common stock will be converted into the right to receive 0.449 shares of common stock of ATK, with cash paid in lieu of fractional shares. At closing of the merger, ATK will be renamed Orbital ATK, Inc. and shares of Orbital ATK common stock will trade under the new ticker symbol “OA” on the New York Stock Exchange beginning February 10.

FMI: www.orbital.com