For what it's worth, I think Poloniex is currently owned by Circle.
True, but apparently he is still part of the company (possible still as the CEO) - at least according to his Linkedin profile[1].
Founder and Ceo
Poloniex, LLC
jan 2014 moment
5 years 6 months
I can't say how accurate that is tho.
[1]
https://www.linkedin.com/in/tristan-d-agosta-0a4529172/