Tesla CEO Elon Musk has taken a 9% stake in Twitter to become its largest shareholder after raising questions about the social media platform's dedication to free speech.

Yet in recent weeks Musk, who has 80 million Twitter followers and posts there often, has questioned free speech on Twitter and whether the platform is undermining

The regulatory filing Monday describes Musk as a long-term investor looking to minimize his buying and selling of the shares.

He has also pondered starting a rival social media network, and industry analysts are skeptical about whether the mercurial CEO would remain on the sidelines for long.

more aggressive ownership role of Twitter," Dan Ives of Wedbush Securities said in a client note early Monday.Twitter's stock surged 20% before the opening bell Monday.

Musk told his more than 80 million followers on Twitter that he was " giving serious thought " to creating his own social media platform and has clashed repeatedly with