Twitter (TWTR) shares were up over 25% in premarket trading early Monday on the news that Elon Musk had taken a significant stake in the social media company, according to a regulatory filing released the same day.

Musk now owns 73,486,938 shares of Twitter, or a 9.2% stake in the company, according to the Securities and Exchange Commission filing.

Musk’s stake is worth $2.89 billion, based on Twitter’s closing price on Friday, CNBC reported.

Twitter’s shares were trading at about $49 per share on Monday in premarket trading.

Musk, who has been an avid user of Twitter, has seemingly caused many companies’ stocks to soar as a result of a single Twitter post.

The Tesla CEO has what some refer to as the “Musk effect,” where his tweets can send the market into a buying frenzy, no matter the topic.

In one instance, in early January 2021, Musk suggested to his legion of 80.1 million fans that they should “Use Signal” – a social chat app.

The app was not listed on the New York Stock Exchange, but a medical device company of the same name was and gained 438% the same day due to Musk’s tweet, the New York Post reported. The Signal app, however, benefited as well, garnering 7.5 million downloads during the week of Musk’s post, according to CNBC.

In another instance, in late January 2021, Musk simply posted “Gamestonk” in reference to GameStop, sending shares of the company up 60% just hours after the tweet from the billionaire, who has a net worth of $273 billion, according to the Bloomberg Billionaires Index.

In another instance also in late January 2021, Musk posted a tweet about how he loved the shopping site Etsy after buying a hand-knit wool Marvin the Martian helmet for his dog, sending shares of the site up 6%.

In addition, Musk has posted several times on Twitter about Dogecoin, causing the cryptocurrency to spike in price.

In September 2021, Musk posted on Twitter that he took home the ultimate Dogecoin symbol - a Shuba Inu dog named Floki as a pet, sending the price of the coin up 2.82%. A number of Floki-based currencies also emerged in anticipation of the Tesla CEO getting Floki.

As of Monday premarket hours, shares of Twitter were trading at $48.99, up $9.68 or 24.62%.

Two US senators requested a federal probe of claims about Autopilot by Tesla and its chief executive, Elon Musk
Two US senators requested a federal probe of claims about Autopilot by Tesla and its chief executive, Elon Musk AFP / Brendan Smialowski