WASHINGTON — Falls Church-based Northrop Grumman received final regulatory approval Tuesday for its acquisition of rocket maker Orbital ATK, creating a huge Northern Virginia contracting company with 80,000 employees worldwide.

The Federal Trade Commission signed off on the $9 billion deal, which includes $7.8 billion in cash and the assumption of $1.4 billion in Orbital ATK debt. Northrop expects the acquisition to close after the stock markets close today.

As a result, Northrop has raised its financial guidance for 2018 and now expects full-year revenue of about $30 billion, about $3 billion more than its most recent financial guidance in April.

Orbital ATK is now known as Northrop Grumman Innovation Systems — a new, fourth business sector for the company.

Orbital ATK itself is the result of the 2015 merger or Orbital Sciences Corp. and the aerospace and defense groups of Alliant Techsystems Inc.