Elon Musk joins Twitter board of directors after becoming its largest shareholder

In a tweet on Tuesday, Twitter CEO Parag Agrawal said he was "excited to share" that Musk was joining the board, adding that "through conversations with Elon in recent weeks, it became clear to us that he would bring great value" to the Board."

Following the announcement, Musk said he was looking forward to working with Parag and the board of directors to make "significant improvements to Twitter in coming months."

The SpaceX and Tesla CEO will serve as a Class II director until 2024, according to a filing with the Securities and Exchange Commission. As a Class II director, Musk is barred from becoming the beneficial owner of more than 14.9% of the company's common stock.

A Class II director role can be used as an anti-takeover measure by companies, The Verge has noted.

On Monday, the SEC reported that Musk purchased a 9.2% stake in Twitter. The purchase made Musk the largest individual shareholder of the company.

His purchase followed months of complaining about the social media service's speech policies. In March, for example, the outspoken billionaire polled Twitter users about whether the platform adhered to its own free speech policies.

Although Musk's stake is the largest, it's considered a passive interest. Purchase of passive interest shares often indicate that a shareholder isn't trying to control or influence the company.

Hours after news of his share purchase broke, Musk created another poll asking users about their interest in an edit button. In a retweet, Twitter CEO Agrawal said that users should "vote carefully," since the results of the poll would "be important."