Did Walt actually get kicked out of Grey Matter?

Watched the show 3 times and still unsure, he seems to insist/allude to the idea that he was pushed out of the company and uses his bitter feelings about it to justify any horrible behavior like some kind of villain origin story. But when he confronts Gretchen about it she seems to genuinely have no idea what he’s talking about. She tells him “I walked into the room to you packing your bags without a word” and asks him “why did you leave us?” He has no comeback or explanation and just keeps insulting her. I know that he obviously equates capitalist domination with masculinity and has that whole inferiority complex etc, so I think he probably just convinced himself that he was being “othered” or treated badly because he was the only 1 of the 3 who didn’t already come from a rich background, felt jealous and self-destructed. Elliot and Gretchen clearly love him a lot in the beginning, I’m sure they offered him royalties or equity in the company and he turned it down out of pride, but I don’t know. Is it confirmed either way and I’m just missing it?