I wonder about 2Sigma. I seem to naively assume that contributing to a lot of open source projects equals great engineering culture, and this company does seem to have a lot of lead devs from large OS projects.
It may not affect open-source teams though, only the finance side, and it could have changed since 2014-2016 when some of my former colleagues were there.
I also think it's telling that Wes McKinney decided to create Ursa Labs. I know Two Sigma is partnering in the early stages, but I read it as clearly a sign that he wasn't empowered with whatever he was promised by them.