Elon Musk's 9% stake in Twitter causes shares to rise 27%.

• According to the 13G filing released Monday, Musk owns 73,486,938 shares of Twitter, which represents a 9.2% passive stake in the company.
• Based on Twitter's closing price on Friday, the stake is valued at $2.89 billion.
• Less than two weeks after Musk criticized the company and polled people on Twitter about whether Twitter adheres to free speech principles, Musk bought Twitter.

Elon Musk, an outspoken CEO, recently became the largest outside shareholder in the social media stock after criticizing the company for not upholding free speech.

According to a Securities and Exchange Commission 13G filing released Monday, Elon Musk owns 73,486,938 shares of Twitter, which represents a 9.2% passive stake in the company, and the stake is worth $2.89 billion, based on Twitter's closing price Friday.

Twitter's failure to adhere to free speech principles fundamentally undermines democracy, as criticized by Musk. He polled people on Twitter about the issue and asked what should be done.

Last month, Musk stated that he was thinking about creating a new social media platform.

Investors were bidding shares higher on the possibility that this could result in something more, causing Twitter stock to surge more than 27%.

Dan Ives, a Wedbush analyst, stated on CNBC's "Squawk Box" on Monday that Musk could adopt a more confrontational approach on Twitter, which could potentially result in a buyout.

Ives stated that this makes sense based on what Musk has discussed on social media.

Twitter declined to comment.

Despite being a regular user of Twitter with over 80 million followers, some of Musk's tweets have caused controversy.

The 12 months following Musk's tweet about securing funding to take Tesla private at $420 per share were a tumultuous period for both Musk and Tesla shareholders. Despite setting new performance records, the company faced litigation, government inquiries, and layoffs. Additionally, Musk reached a settlement with the SEC that stripped him of his position as chairman at Tesla.

— CNBC’s Jessica Bursztynsky contributed to this report.