The US firm Spirit Aerosystems has finally taken control of Bombardier's Northern Ireland operations.
It ends a period of uncertainty for the firm's 3,000 employees in Northern Ireland.
The deal with Spirit, which is based in Kansas, was originally reached more than a year ago.
Since then the aerospace industry has been in a state of turmoil with some major deals collapsing.
Spirit renegotiated the terms of the original deal with Bombardier with the cash payable falling from $500m (£384m) to $275m (£211m).
Michael Ryan, the general manager of Spirit Belfast, said that finalising the deal was a "momentous milestone".
He said the Belfast operation brings "a rich heritage in aviation, including world-class skills in design, manufacturing and aftermarket".
Spirit is a major supplier to Airbus and Boeing.
The company wants to do more work for Airbus and buying Bombardier's Northern Ireland operation is part of that strategy.
The wings for the Airbus A220 are made at the firm's Belfast plant.
Spirit has also bought a Bombardier factory in Morocco and a repair facility in the US.
Northern Ireland's first minister, deputy first minister and economy minister welcomed the successful completion of the sale.
The ministers also thanked Bombardier for their positive influence on Shorts during its 31 year ownership of the company.
First Minister Arlene Foster said: "The finalisation of this sale today is positive news, bringing a level of certainty and much needed optimism to workers and the broader community."