(The Hill) — Twitter shares rose over 20 percent Monday morning on news that Tesla CEO Elon Musk acquired a 9.2 percent stake in the social media platform.

Musk is now the largest outside shareholder with 73,486,938 shares, according to a Securities and Exchange Commission filing released Monday.

The Tesla chief is a very active Twitter user with a committed fan base. Just last week he polled his 80 million followers on whether the platform “rigorously adheres” to principles of free speech.

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Over 70 percent responded “No,” prompting Musk to ask whether a new platform is needed.

Musk has previously gotten into hot water over his tweets and is currently in a legal fight with the SEC over an agreement restricting his posts about Tesla.

The deal to acquire a stake in Twitter comes months after long time CEO Jack Dorsey departed the company.

Parag Agrawal replaced Dorsey in November, prompting Musk to tweet a meme depicting Agrawal as Joseph Stalin and Dorsey as Soviet secret police chief Nikolai Yezhov being pushed into water.