Bombardier's Northern Ireland operations were sold to the US company Spirit AeroSystems.
The Canadian company put the factories up for sale in May as part of a reorganization of their business.
The aerospace manufacturer employs about 3,600 people in Northern Ireland.
Spirit, headquartered in Wichita, Kansas, is an important supplier to Airbus and Boeing. Earlier this year, Spirit's chief executive said the company wanted to work more for Airbus.
The purchase of Bombardier's Northern Ireland business is part of this strategy.
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Spirit also buys a Bombardier factory in Morocco and a repair shop in the US.
A Greater Supply Chain Position?
Bombardier has sold its commercial aerospace equipment to focus on trains and business jets: this is the last part of it.
Spirit was originally founded as a spin-out of an aerospace company Boeing.
Boeing remains the biggest customer, but part of Spirit's strategic plan is to reduce its dependence on Boeing.
Earlier this year, Spirit wanted to deliver more to Airbus, expand its manufacturing facilities, and get more military work.
Now that a deal has been made with Bombardier, two of them are undeniable and have a much larger position in the Airbus supply chain.
Bombardier, based in Montreal, has more than 68,000 employees in 28 countries.
The company employs approximately 3,600 people at several sites in Northern Ireland – in Ostbelfast, Newtownabbey, Dunmurry and Newtownards.
The Belfast plant builds wings for Airbus and is the largest high-tech manufacturer in Northern Ireland.