Interestingly (and admittedly unrelated to your point), Boeing used to both build and operate planes, as well as build components for planes. The US government

Interestingly (and admittedly unrelated to your point), Boeing used to both build and operate planes, as well as build components for planes. The US government passed a law to break them up in 1934 - the plane manufacturing became Boeing, the air operations became United Airlines, and the eastern components manufacturing became United Aircraft Corporation, later United Technologies.