IBM was huge in the 80s and 90s. The majority of business PCs were IBM. They made their own CPUs, RAM, Sound Cards, Network Cards, Video Chipsets, Hard Drives and Optical Drives. If you could buy an IBM case you could build a completely IBM PC. In addition to having a finger in every hardware pie, They had a huge software lineup, with the dominant business servers and databases. They owned their own international radio network. They were largest employer in the world. I ran OS/2 as my primary OS for about eight years. They squandered almost all there software assets.
They are strong now but as a much smaller focused service company.