Elon Musk took a 9.2% stake in Twitter Inc. to become the platform’s biggest shareholder, a week after hinting he might shake up the social media industry.

Twitter shares surged as much as 27% after Musk’s purchase was revealed Monday in a regulatory filing.

The gain marked the stock’s biggest intraday increase since its first day of trading following the company’s 2013 initial public offering.

Tesla is going to post its financial results for the first quarter of 2022 after market close on Wednesday, April 20, 2022.

The stake is worth about $2.89 billion, based on Friday’s market close.

Musk has been one of the biggest personalities on Twitter and has regularly run into trouble on the platform.

Musk, already the world’s richest person according to the Bloomberg Billionaires Index, has made about $1.1 billion on his holding since mid March, based on the pop in Twitter’s shares in early trading Monday.