In 2018, which American aerospace and defense company acquired Orbital ATK?

In 2018, Northrop Grumman acquired Orbital ATK.

Orbital ATK was created in 2015 through the merger of Orbital Sciences Corporation with the aerospace and defense businesses of Alliant Techsystems, commonly known as ATK. The combined company made launch vehicles, satellites, missile systems, rocket motors, ammunition, and spacecraft, including the Cygnus cargo vehicle used for International Space Station resupply.

Northrop Grumman announced the planned purchase in September 2017. The transaction was valued at about $9.2 billion, comprising $7.8 billion in cash plus the assumption of approximately $1.4 billion in debt. Orbital ATK shareholders approved the deal in November 2017, and regulators approved it with conditions in June 2018.

After closing, Orbital ATK was renamed Northrop Grumman Innovation Systems. In 2020, Northrop Grumman reorganized that business into other divisions, including its Space Systems and Defense Systems operations. The other choices are major aerospace or defense companies, but none acquired Orbital ATK.