I believe that Boeing owned De Havilland for a brief period. At the time it was Hawker-DeHavilland, and Hawker had some nice military contracts.

Boeing being very interested in the military side of HDH they bought the company. They were less interested in the commercial side (For christ sake, it had props! That can’t be good :D) so they sold that part.

Bombardier describes it on their website as follows:
“In March 1992, acquisition of the assets and operations of Ontario-based de Havilland, manufacturer of the Dash 8* turboprop regional aircraft. Acquisition made through a new company, de Havilland Inc., whose equity is shared by Bombardier (51%) and the Province of Ontario (49%). In January 1997, Bombardier completed the purchase of the 49% interest in de Havilland, owned by the Province of Ontario.”

I think that Boeing kind a regrets having sold De Havilland. Their main product at the time may have had props, but the CRJ turned out to be quite a succes!