Elon Musk, the CEO of electric-car maker Tesla, offered to buy the social media company for $54.20 per share in cash.

"I am offering to buy 100% of Twitter for $54.20 per share in cash, a 54% premium over the day before I began investing in Twitter and a 38% premium over the day before my investment was publicly announced. My offer is my best and final offer and if it is not accepted, I would need to reconsider my position as a shareholder," Musk said in a statement.