Tesla and SpaceX CEO Elon Musk now owns 9.2 percent of Twitter after purchasing $2.89 billion in stock, according to a US Securities and Exchange Commission (SEC) filing spotted by CNBC. The purchase follows recent criticism by Musk over the social media site’s free speech policies. “Given that Twitter serves as the de facto public town square, failing to adhere to free speech principles fundamentally undermines democracy,” he tweeted last week.

Musk is a prolific Twitter user and has over 80 million followers, but the platform has also brought him trouble. Most famously, in 2018 he tweeted that he had “funding secured” to take Tesla private at $420 a share, setting off an SEC lawsuit that cost him $20 million and his spot as chairman of the board. Musk recently challenged the settlement, saying that the SEC overstepped its authority. He’s asking a federal judge to terminate his agreement requiring some tweets to be vetted by a lawyer.

Along with the comment, Musk launched a Twitter poll last week with the question “Do you believe Twitter rigorously adheres to this [freedom of speech] principle?” He also mused about the idea of starting his own social media platform, saying he was giving it “serious thought.” 

In a follow-up tweet, Musk said that “the consequences of this poll will be important,” and that prediction has now apparently come true. His stake in Twitter is still a passive one, but he could up the stakes somewhat. “This eventually could lead to a buyout,” analyst Dan Ives told CNBC. Musk is now the platform’s largest shareholder, and Twitter shares have reportedly surged more than 25 percent in premarket trading, according to CNBC. 

Update 4/4/2022 11:52 AM: The post has been updated with information that Musk is now Twitter’s biggest shareholder.