The BBC has been unable to verify the post was written by Mr Musk himself, but it has pushed the shares 6% higher.
Elon Musk said today he might take Tesla private if its stock reaches $420 a share. Many major Wall Street bankers contacted by Reuters said on condition of anonymity that they were not aware of Musk's plans ahead of his tweets, and several expressed skepticism that a leveraged buyout of Tesla could be financed given the company's negative cash flow.
The company did not immediately respond to requests for comment.
Donald Trump re-imposes Iran sanctions lifted by Barack Obama
While Iran's economy is in poor shape, it isn't in the critical condition it was when the Iran nuclear deal was reached. The president doubled down on criticism on in his statement on sanctions on August 6.
The Public Investment Fund, or PIF, acquired shares in Tesla over the last few months as part of its wider investment strategy, according to a person familiar with the transaction.
Tesla shareholders would need to vote in favor of going private before the decision is finalized, Musk concluded.
He also said that he would hold on to his almost 20% stake in the company if it were taken private, and that he wouldn't expect himself or any other investor to have a controlling vote after the buyout. At $420 a share, Tesla would have a market cap of around $71 billion.
In an interview with Bloomberg News in January 2015, he spoke of the benefits of running his closely held rocket company Space Exploration Technologies Corp. and his frustrations with having taken Tesla public in June 2010.
Everton are close to accepting Barcelona's demands for Yerry Mina
He claims to have heard from Mina's agent and uncle Jair Mina that United is a much more likely destination for the 23-year-old. The France global has been heavily linked with a switch to the Nou Camp this summer.
"The Securities and Exchange Commission issued a report that makes clear that companies can use social media outlets like Facebook and Twitter to announce key information in compliance with Regulation Fair Disclosure (Regulation FD) so long as investors have been alerted about which social media will be used to disseminate such information", the commission wrote in a 2013 press release. Before Musk's tweet, Tesla had a market value of $58 billion, already higher than that of General Motors or Ford, even though those companies are significantly larger and more profitable.
Musk also wants Tesla's employees to remain shareholders.
Tesla has not confirmed whether the tweet was real - or if the CEO's account was hacked. I think he's serious.
George Galliers of Evercore ISI said he believed the tweet was serious. He added: "I can't believe this is something to bluff or make fun of". It followed the news that Saudi Arabia's sovereign wealth fund had built a less than 5 percent stake in Tesla worth about $2 billion.
Kei Nishikori nemesis Alexander Zverev reaches Citi Open semi-finals
After advancing to the quarterfinal round, former world No. 1 Andy Murray withdrew from the Citi Open in Washington Friday night. When play resumed, Zverev took a second break thanks to a series of errors by Nishikori and closed out the match. "It's not good.