NBI in Boulder, CO declared bankruptcy in 1991 ... they made proprietary hardware and software combo for word processing which briefly became the standard for word processing world wide ... but when PCs came along, they soon dominated word processing, spreadsheets, etc. with much cheaper hardware and software. NBI execs refused to repackage their software for PCs, missing the chance to become the PC standard for word processing, even though everybody and his uncle’s brother urged them to do that ... ossified management killed NBI ...
Digital Equipment Corporation: Ken Olsen CEO, defunct 1998; refused to transition their proprietary stable of hardware, software and operating systems to Unix and other standards; co-inventor of Ethernet but failed to capitalize on it ... ossified management killed DEC ...
Kodak had the technology and engineers to dominate in digital cameras and digital printers, but failed to aggressively reorient the company in that direction for fear of undercutting their film sales ... filed for bankruptcy in 2012 but is still limping along ... ossified management killed Kodak ...
I think it was floor 3 of building 11 in DEC's Maynard, MA facility (the "Mill") where all of the VPs who had nothing to do were put into storage. They all thought better days were coming.
Texas instruments, RadioShack, circuit city, Firestone, the one major bookstore that went out of business, Bed Bath and Beyond, Craker Barrel, AOL, Best Buy, Jack-in-the-Box,
The DEC PDP-11 was the computer upon which UNIX was created.