Holy shit. If the following qoute is to be believed, it's almost certainly the Saudis backing it since I don't know who else has that kind of money and also considering the Saudis hit the 5% investment mark which requires you to announce it at the perfect moment. Shit, with tsla dropping back down now and elon being quit, i think it helps the case more that it is them because I would want them to have the full opportunity to buy as much stock now while it is below 420$ before the buyout is confirmed.
"Musk previously talked with Saudi Arabia's sovereign wealth fund about a take-private deal, said one of the people. Saudi's Public Investment Fund bought a 3 percent to 5 percent stake in the electric car maker, The Financial Times reported earlier this week. It isn't yet known whether Saudi's Public Investment Fund has agreed to commit money to the transaction."