Elon Musk revealed a 9.2% stake in Twitter Inc, worth nearly $3 billion, making him the largest shareholder after raising questions about the social media platform’s dedication to free speech. Musk’s move comes on the heels of his tweet that he was giving “serious thought” to building a new social media platform.

“It does send a message to Twitter…having a meaningful stake in the company will keep them on their toes, because that passive stake could very quickly become an active stake,” said Thomas Hayes, managing member at Great Hill Capital LLC.

A prolific Twitter user, Musk has over 80 million followers since joining the site in 2009 and has used the platform to make several announcements, including teasing a go-private deal for Tesla that landed him in regulatory scrutiny.

The regulatory filing Monday describes Musk as a long-term investor looking to minimize his buying and selling of the shares. Musk owns 73.5 million Twitter shares, which are held by the Elon Musk Revocable Trust, of which he is the sole trustee. Vanguard is Twitter’s second-biggest shareholder, with an 8.79% stake, according to Refinitiv data.

“We would expect this passive stake as just the start of broader conversations with the Twitter board/management that could ultimately lead to an active stake and a potential more aggressive ownership role of Twitter,” Dan Ives of Wedbush Securities said in a client note Monday.

His Twitter stock purchase comes as Musk is locked into a bitter dispute with U.S. securities regulators over his ability to post on Twitter. Musk’s lawyer has contended in court motions that the U.S. Securities and Exchange Commission is infringing on the Tesla CEO’s First Amendment rights.

Musk’s revelation about his stake in Twitter shares comes two days after Tesla Inc. posted first-quarter delivery numbers. While the company delivered 310,000 vehicles in the period, the figure was slightly below expectations.