Elon Musk, the billionaire businessman, now owns a 9.

The details can be found in a filing with the Securities and Exchange Commission in the United States.

Musk purchased 73,486,938 Twitter shares in March, according to the US agency.

The news of the $2.89 billion holding raised the company's stock by approximately 25% in pre-market trade.

With more than four times the 2.25 percent held by Twitter founder Jack Dorsey, the Tesla founder becomes the largest shareholder.

Musk conducted a vote on March 24 to determine if the social media platform's algorithm should be open source.

Later, the billionaire inquired about Twitter's adherence to the principle of free expression.

After the majority said no, Musk questioned if a new social networking site was needed.