Billionaire Elon Musk, owner of electric car maker Tesla, bought 9.2% of Twitter shares for nearly $3 billion, a week after signaling he would rock the world of social media.
This increased the value of the shares of the social network by 26% before the opening of the markets.
Musk is known for his critical eye on Silicon Valley giants.
On March 25, he asked his Twitter followers if they considered Twitter to respect freedom of expression. More than 70% of the responses had been negative.
This stake will put pressure on Parag Agrawal, the current CEO, who replaced Jack Dorsey (the co-founder of Twitter) at the head of the company last November.
Last December, Musk posted a meme featuring Agrawal as dictator Joseph Stalin.