Early on Monday, Musk sent a new document to the government.

The world's wealthiest man laid out his possible intentions toward the micro-blogging site, which he has amassed a 9.2 percent stake in.

According to a document filed with the SEC, Mr. Musk could increase his ownership of the company by buying more shares of it. The document noted that he could express his views on social media. He had the right to change his plans at any time.

It was either a promise or a threat. Either way, the filing encapsulated the perilous situation that now exists for the micro-messaging service. Mr. Musk could use the social media platform against himself and even buy enough shares to take over the company.

The founding team and board of directors of the company have suffered more than their fair share of incompetence.

A week of high-stakes drama between the billionaire and the company ended with a filing. Last Monday, it was revealed that Mr. Musk had amassed stock in the company that was worth more than $3 billion. He agreed to not own more than 14.9% of the company if he joined the board. All of those bets were off and Mr. Musk wouldn't become a director.

The company's executives and board members are not sure what happened between Mr. Musk and the company. It leaves a company that has survived founder infighting, boardroom revolts and outside shareholder ire with an activist investor.

Mr. Musk is known for being unpredictable and outspoken, often using his social media accounts to criticize, insult and troll others. He was freed from corporate governance rules that would have required him to act in the best interests of the company and its shareholders by not joining the board.

After Mr. Musk told the company of his decision on Saturday morning, he leaned into that freedom. He suggested changes to the company's name such as removing the "w" from it and opening its San. Some of the posts were deleted.

Ele Klein, co-chair of the global Shareholder Activism Group at the law firm, said that this is not typical activism or anything like activism that they have seen before.

The co-head of the Shareholder Activism practice at a law firm said he sympathized with the plight of the micro-blogging site.

Mr. Musk did not reply to questions. He liked a message that suggested the company wanted to restrict his free speech rights.

Mr. Musk would have had to behave as a fiduciary of the company, according to Parag. The biography of Mr. Musk that was published on Sunday was still visible on Monday.

Twitter’s chief executive, Parag Agrawal, tweeted on Sunday that the company would remain open to Mr. Musk’s input.
ImageTwitter’s chief executive, Parag Agrawal, tweeted on Sunday that the company would remain open to Mr. Musk’s input.
Twitter’s chief executive, Parag Agrawal, tweeted on Sunday that the company would remain open to Mr. Musk’s input.Credit...via Twitter

Mr. Musk has disrespected corporate governance rules before. He was charged with securities fraud after he wrongly stated that he had secured funding to take the company private. The S.E.C. fined Mr. Musk $20 million and he agreed to step aside as chairman for three years.

He agreed to allow the company to review his statements. The S.E.C. asked a judge to hold him in contempt for violating the settlement terms by continuing to violate them.

Half a dozen current and former workers who were not authorized to speak publicly said employees were dismayed and concerned by Mr. Musk's antics. Employees questioned how Mr. Musk knew that he hadn't visited the building in a while. They pointed out that Mr. Musk could easily afford to help the homeless in San Francisco.

Others said they were upset by Mr. Musk's criticism of the company's product and business model. Some employees said they were relieved after reading that Mr. Musk wouldn't join the board.

Mr. Musk was scheduled to answer questions from employees at the question-and-answer session. A person with knowledge of the decision said the session had been canceled.

The second time in two years that Twitter has dealt with an activist investor, it was Mr. Musk. In 2020, the investment firm used its position to push for changes, including the ousting of Jack Dorsey as chief executive, and more aggressive financial growth. Mr. Dorsey left in November.

The typical approach for activist investors is to acquire a significant stake in a company and then press for governance and strategy changes to drive up the stock price.

An analyst at LightShed Ventures said that an activist is very clear about their intentions. We don't know what Musk's true motivation is. Is this person having fun? Is this person trying to change something? Is he trying to drive the stock higher?

The company's founders did not structure the company's shares in a way that gave them more control, which is why it is vulnerable to activists. The voting power of the founders of both companies has allowed them to exert control over the direction of their companies.

Mr. Musk was taking a more casual approach than other activist investors.

She said that it was not a core activity for Musk to have his opinions heard.

What is fun for Mr. Musk may be less so for his followers. The relief that he was no longer joining the board was short-lived, the current and former employees said, when they realized that he was no longer bound by an agreement to not buy more stock or take over the company.

The current and former employees said that Mr. Musk could still be involved with the social networking site. Several people said they were afraid of what would come next.

Lauren contributed to the reporting.