Elon Musk, billionaire entrepreneur and CEO of Tesla announced a $43 billion cash offer for Twitter on Thursday, claiming that the social media behemoth should go private to expand and become a platform for free speech. "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 wrote in a letter to Chairman Bret Taylor. Musk's offer price of $54.20 a share is a 38% premium to Twitter's close on April 1, the last trading day before his 9.1% holding in the social media network was made public. On Thursday, the offer was made public in a regulatory filing.