Tesla boss Elon Musk has offered to buy Twitter, saying he is the right person to "unlock" the social media platform's "extraordinary potential".
In a surprise announcement, Mr Musk said he would pay $54.20 a share for Twitter, valuing it at about $40bn.
It recently emerged that Mr Musk was Twitter's biggest shareholder after he built up a large stake in the firm.
He said that if his offer was not accepted: "I would need to reconsider my position as a shareholder".
A filing with the US financial regulator appeared to show text and/or voice messages from Mr Musk to Twitter's board, showing that he had raised the idea at the weekend that the business should go private.
Mr Musk had been invited to join the board, but Twitter announced on Sunday he had decided against it.
In the messages published in the filing, Mr Musk said he was not "playing the back-and-forth game" and said of his offer: "It's a high price and your shareholders will love it."
He said he would have to sell his shares if the deal did not go through.
"This is not a threat, it's simply not a good investment without the changes that need to be made," he added.
In his filing with the US regulator, Mr Musk said he had invested in Twitter because "I believe in its potential to be the platform for free speech around the globe, and I believe free speech is a societal imperative for a functioning democracy.
"However, since making my investment I now realize the company will neither thrive nor serve this societal imperative in its current form. Twitter needs to be transformed as a private company."
He added: "Twitter has extraordinary potential. I will unlock it."
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