Entrepreneur and business magnate Elon Musk announced Thursday that he has proposed to buy Twitter for $54.20 per share, which amounts to around $43 billion.

The decision comes after Musk, the founder of electric carmaker Tesla and space exploration company SpaceX, announced on April 4 that he bought a 9.2% share in Twitter, becoming the social media platform’s biggest investor.

"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 wrote in a security filing to the US Securities and Exchange Commission.

"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.

Musk noted that his offer is final, and said that if it is not accepted, he would need to reconsider his position as a shareholder.

"Twitter has extraordinary potential. I will unlock it," he added.

The stock price of Twitter was up 3.1% to $45.85 per share at 0640EDT (1040GMT) before the market opening at the New York Stock Exchange on Thursday./agencies