Good Ventures / Open Philanthropy (Dustin Moskovitz) funded GiveWell and OpenAI, and GiveWell's leadership floated to OpenAI, but I'm not convinced that GiveWell funded OpenAI.
https://www.givewell.org/about/gw-op-relationship
They are certainly both entangled with the Effective Altruism community, but GiveWell came from the "humanities/finance" side, not the tech bro technoutopia side.
