You keep saying that but they are literally sub companies of the same larger conglomerate. Their CEO and founder is the same person, he is also both of their primary shareholders.

Same group of companies, the distinction is completely irrelevant.

One’s a market maker + bank, one’s a fund. I understand it’s against the grain to hold this opinion, probably because it’s inherently not conspiratorial, but they do different things and regulated/managed entirely differently.

They are still owned by the same group of people, with conflicting interests: one side supports a trading platform, the other side just bailed out a moribund fund and needs to make that money back.

What side do you think wins given the huge hole left in Citadel after propping up Melvin?

Companies do not make decisions. People owning these companies make decisions.

Mitsubishi Electric != Mitsubishi.

And Alphabet != Google! /s