The Big Eight dominate Vector technology and society, but they aren’t alone in the universe. Spin-off minicorps, often with between 3-6 core members and a single space ship, are available for hire, a rich resource for unique skills and plausible corporate deniability.
Two established minicorps have been named in game canon: Genesis, MarsCo’s educational subsidiary, developing the neuroplex system and training generations of vectors without all that bothersome learning time. Reividolon is a TTI-owned minicorp with a strong role in the Fate’s Fangs novel, a medical research group with a focus on epidemiology. The author mentioned the Marsco Security Force in an interview, Marsco’s enforcement group in part became IRPF, but still exists. There are almost certainly others.
Currently there are two known “dead” megacorps, and two deceased large corporations. Interestingly, most were single-species corporations. Genotype helped refine the rat race into the red-eyed, steely wall of black fur that they are today, and were terminated by the rebellion of the mouse slave race. In the distant past, an unnamed pair of large, Felidae-owned corporations, edging into Megacorp size, were responsible for two race wars, and seem to have had their corporate charters revoked to protect the racial dignity of catkind. Another unnamed megacorp flared up some 150 years ago, the corp that commissioned the defunct Bluesky station now called “Longbow…” Sadly, they died of insurance fraud.
Of all of these, there may be many more, 700 years is a long time for any empire, let alone a business concern.