Elon Musk took aim at Twitter with a $41 billion cash offer on Thursday, with the Tesla CEO and billionaire entrepreneur saying the social media giant needs to be taken private to grow and become a platform for free speech.

“Twitter has extraordinary potential. I will unlock it,” Musk, who is already the company’s second-largest shareholder, said in a letter to Twitter’s board on Wednesday.

The offer was made public in a regulatory filing on Thursday.

Musk’s offer price of $54.20 per share represents a 38 percent premium to Twitter’s April 1 close, the last trading day before his 9.1 percent stake in the social media platform was made public.

Musk rejected an invitation to join Twitter’s board this week after disclosing his stake, a move which analysts said signaled his takeover intentions as a board seat would have limited his shareholding to just under 15 percent.

He told Twitter it was his best and final offer and said he would reconsider his investment if the board rejects it.

“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 in his letter to Twitter Chairman Bret Taylor.

Musk, who calls himself a free-speech absolutist, has been critical of the social media platform and its policies and recently ran a poll on Twitter asking users if they believed it adheres to the principle of free speech.