Elon Musk has proposed to buy Twitter for about $41 billion in cash, in a move that comes just days after the Tesla CEO rejected a seat on the social media company’s board.

The billionaire said the social media company he has often criticized needs to go private to see effective changes.

Musk's offer price of $54.20 per share, which was disclosed in a regulatory filing on Thursday, represents a 38% premium to Twitter's April 1 close, the last trading day before Tesla CEO’s more than 9% stake in the company was made public.

The total deal value was calculated based on 763.58 million shares outstanding, according to Refinitiv data.

Twitter’s shares jumped 12% in premarket trading.

"I invested in Twitter as 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," Musk says in the filing.

"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."

Musk said the offer "is my best and final offer and if it is not accepted, I would need to reconsider my position as a shareholder."

He said Morgan Stanley was the financial adviser for the offer.

Twitter said it has received Musk's offer and will decide whether it is in the best interests of shareholders to accept or continue to operate as a publicly-traded company.

"The Twitter Board of Directors will carefully review the proposal to determine the course of action that it believes is in the best interest of the Company and all Twitter stockholders," the company said.

Musk rejected an offer to join Twitter’s board earlier this week after disclosing his stake in the company, a move that analysts said signaled his intention to take over the company as a board seat would have limited his stake to just under 15%.

Analyst Daniel Ives of Wedbush said in a client note that he believes "this soap opera will end with Musk owning Twitter after this aggressive hostile takeover of the company."

He thinks it would be hard for any other bidders or consortium to come forward and said Twitter’s board will likely be forced to accept Musk’s offer or start a process to sell the company.

The billionaire has amassed over 80 million followers since joining the site in 2009 and has used the platform to make several announcements, including teasing a go-private deal for Tesla that landed him in hot water with regulators.

Musk and Tesla in 2018 agreed to pay $40 million in civil fines and for Musk to have his tweets approved by a corporate lawyer after he tweeted about having the money to take Tesla private at $420 per share.

That didn’t happen but the tweet caused Tesla’s stock price to jump. Musk’s latest trouble with the U.S. Securities and Exchange Commission (SEC) could be his delay in notifying regulators of his growing stake in Twitter.

Musk has described himself as a "free speech absolutist" and has said he doesn’t think Twitter is living up to free speech principles – an opinion shared by followers of Donald Trump and a number of other right-wing political figures who’ve had their accounts suspended for violating Twitter content rules.

Musk has also been sued by former Twitter shareholders who claim they missed out on the recent run-up in its stock price because he waited too long to disclose his stake.

"There will be host of questions around financing, regulatory, balancing Musk’s time (Tesla, SpaceX) in the coming days but ultimately based on this filing it is a now or never bid for Twitter to accept," Wedbush's Ives said.

Twitter’s lower-than-expected user additions in recent months have raised doubts about its growth prospects, even as it pursues big projects such as audio chat rooms and newsletters to end long-running stagnation.

"Twitter has extraordinary potential. I will unlock it," Musk said in his letter.