Tesla founder Elon Musk stunned investors when he tweeted Tuesday that he would push to take his all-electric automaker private in a deal worth billions of dollars, further highlighting the unpredictability of America’s most valuable car company — and its billionaire celebrity chief.

The announcement sent Tesla’s stock soaring on hopes the maneuver would become one of the largest such deals in American corporate history, requiring a turbocharged boost of cash to eject Tesla from public shareholders’ hands.

But Musk, an erratic micromanager infamous for his explosive leadership style, decided to announce the plan with his signature brand of chaos: via a nine-word Twitter message, fired off in the middle of the trading day and hours before his company officially announced the plan.

“What chaos,” said Teresa Goody, a former Securities and Exchange Commission official who now advises companies on securities law and corporate governance. “It is not reasonable to expect investors to monitor and keep track of Elon Musk’s tweets.”

Musk said he had secured funding to take the company private at $420 a share, far above its pre-tweet price of $355, in a deal that could value the company at more than $70 billion. In a letter to employees Tuesday afternoon, Musk added that a final decision had not yet been made and that the proposal would need approval from a shareholder vote.

But many questions remained, including where Musk would get all the money he needed to fund the deal. Neither he nor the company provided any details about financing, leading skeptics to question the viability of Musk’s master plan.

The move prompted immediate blowback from market and legal experts because it broke precedent with how companies traditionally unveil such monumental news: by halting trading or distributing official releases so as not to unduly jolt the markets or boost their share price. Tesla’s stock immediately spiked 7 percent before the company suspended trading Tuesday afternoon to give an official statement.

Harvey Pitt, the SEC chairman under President George W. Bush, said the “extraordinarily unusual” announcement could expose the company to SEC investigations or charges of fraud or stock manipulation if Musk had overstated his part of the deal. The SEC declined to comment on whether it was investigating Musk’s disclosure.

Trading in the company’s shares was halted for 92 minutes Tuesday afternoon — an eternity in stock-market terms — before resuming shortly before the market closed. The stock ended the day up about 11 percent, at $379.57.

Musk has long chafed at Tesla’s public ownership, which allows the company to raise money from shareholders on the open market, because it comes with public disclosure requirements that have forced Musk to routinely defend the embattled company to analysts, journalists and investors.

In his letter, Musk said taking the company private would help reduce distractions from the stock market, where investors betting the company will fail have made Tesla the most shorted company on Wall Street.

“We are at our best when everyone is focused on executing, when we can remain focused on our long-term mission, and when there are not perverse incentives for people to try to harm what we’re all trying to achieve,” Musk wrote.

But taking the company private would greatly reduce visibility for investors eager to see how the company is performing. It would also further consolidate corporate power beneath Musk, who has sparred with analysts, journalists, company critics and former employees when he has believed the company is under attack.

Investors in recent months have been repeatedly unnerved by Musk’s frantic, ferocious leadership style. He slammed investment analysts for asking “boring, bonehead” questions (and later apologized); called a hero of the Thai cave rescue operation a “pedo” (and later apologized); and fired off late-night emails to company employees urging them to remain vigilant for shadowy “outside forces,” saying, “Only the paranoid survive.”

Musk took a much more reserved tone in his letter than his Twitter style, laying out the plan’s rationale and saying “the future is very bright.” Current shareholders, Musk wrote, would be allowed to stay on as private investors or could be paid for their shares at a healthy profit. Musk — Tesla’s top shareholder, with 20 percent of its stock — has not said when he expected to call for a shareholder vote.

The company did not offer comment or details beyond the employee letter, and in that vacuum of information, many raced to Musk’s Twitter account, where he traded jokes, answered questions and dribbled out bits of market-shaking news.

Musk said that he wouldn’t be selling shares, that he expected to remain as CEO, and that he expected the deal would save his company “a lot of headaches.” It “will be way smoother & less disruptive as a private company,” Musk said, adding that it would end “negative propaganda from shorts.”

Gene Munster, managing partner of the venture capital firm Loup Ventures, said Tesla would perform better as a private company because its grand ambitions — to supercharge renewable energy and revolutionize driving — didn’t always make it easy to satisfy investors’ short-term expectations. But Munster also called for caution, saying, “There is a 1 in 3 chance (Musk) can actually pull this off.”

Musk took Tesla public in 2010 to help raise money for the company’s growth. But his other firms specializing in private spaceflight and underground supertrains — SpaceX and The Boring Company — remain private, and Musk has recoiled at the idea of exposing them to shareholder control. In 2013, he emailed SpaceX employees that he was “hesitant to foist being public” on the company “given the long term nature of our mission.”

Musk’s tweet came shortly after the Financial Times reported that the state investment fund of Saudi Arabia had become one of Tesla’s biggest shareholders after recently accumulating a roughly $2 billion stake.

The oil-rich kingdom now led by Crown Prince Mohammed bin Salman has shown a keen interest in flashy technological investments, including announcing a $1 billion investment last year in the private space companies run by Virgin Group founder Richard Branson.

Tesla said last week that it had burned through more than $700 million in cash during the second quarter but made roughly $4 billion in revenue amid increased production of its new Model 3 sedan. Musk said the automaker, which has never made an annual profit, would be profitable by the second half of the year.

Tesla has about $10 billion in outstanding debts and about $2 billion in cash reserves, but Musk has asserted in recent months that the company would have no need to raise new funds. “Are we running low on money? The answer is no,” Musk told investment analysts last week.

Musk has wielded his Twitter profile as a battle-ax against the short sellers betting the company’s value will plummet, and over the weekend, he shared a video parody that cast Adolf Hitler as a short seller flying into a rage at Tesla’s recent financial reports. “Dang, turns out even Hitler was shorting Tesla stock …” Musk tweeted.

But he has also been known to use the profile to drop financial bombs to his 22 million followers. On April Fools’ Day, amid growing concerns about the company’s cash stockpile, Musk joked via tweets that Tesla had gone “so bankrupt you can’t believe it.”

Even so, some corporate experts were still surprised by how much the head of a multibillion-dollar global conglomerate had been willing to put in a tweet.

“This isn’t a little disclosure. This is a big disclosure. This is the most significant thing that can happen to an investor in a company,” said Charles Elson, the director of the John L. Weinberg Center for Corporate Governance at the University of Delaware. “It’s a very strange way of doing it and unsettling to investors.”