"Funding secured", Musk said.
Musk tweeted that he hoped all current investors would remain were the company to go private.
Paul Huettner, an associate at a financial advisory firm that specializes in restructuring and bankruptcy, said in a call that announcements like this are normally done after markets close. I own about 20% of the company now, and I don't envision that being substantially different after any deal is completed.
In his tweets, Musk said he would keep his Tesla shares no matter what happens, and noted that he now doesn't hold a controlling interest in the company.
It followed news that Saudi Arabia's sovereign wealth fund had built a less than five per cent stake in Tesla worth about US$2 billion.
"Basically, I'm trying to accomplish an outcome where Tesla can operate at its best, free from as much distraction and short-term thinking as possible, and where there is as little change for all of our investors, including all of our employees, as possible", Musk wrote.
The unusual step taken early Tuesday afternoon came shortly after Musk dropped a bombshell on his Twitter account by announcing he had lined up the financing to buy all of Tesla's stock at $420 per share.
The confusion caused by Musk's Tuesday announcement via Twitter also prompted regulators of the Nasdaq stock market to temporarily suspend trading in Tesla's stock. And if the information in the tweet isn't true, Musk could be looking at some stock price manipulation allegations. A Tesla spokesman declined to comment. It's one of the most shorted stocks out there.
For current shareholders, Musk said he would institute a provision ensuring that their stock be converted into private shares, adding he would 'ensure their prosperity in any scenario'.
Musk has said he expects Tesla to begin being profitable in the third quarter of 2018.
The electric vehicle maker reported revenue of $4 billion in the second quarter of 2018, with $2.2 billion in cash in hand.
Mr Musk did not disclose the source of the funding. The Financial Times earlier reported the investment.
Musk's other companies specializing in private spaceflight and underground supertrains - SpaceX and The Boring Company - remain private, and Musk has shown reluctance about opening them to the public markets.
Tesla doesn't meet the typical profile of a company that can raise tens of billions of dollars of debt.
Despite its challenges, Tesla has remained a favourite among many investors, partly due to their faith in Musk, who made his initial fortune as a co-founder of PayPal and also is the CEO of a trail-blazing aerospace company, SpaceX, that's already private.