>>Octoth+(OP)
Joyent handed Node.js over to a foundation in 2015, and that foundation merged into the JS Foundation to become the OpenJS Foundation in 2019.
I'm not sure if Joyent have any significant role in Node.js maintenance any more.
>>Octoth+55
Microsoft owns npm outright and controls every aspect of the infrastructure that node.js relies on. It also sits on the board (and is one of the few platinum members) of the Linux Foundation, which controls openjs. It is certainly MS.