The boss of Tesla and SpaceX is super-active on Twitter and has more than 80 million followers.
Twitter's shares soared by more than a quarter in pre-market trading on the back of the news, adding about $8bn to its $31.5bn value, before easing back to 21% up in early trading. As of late Monday, the share price was up 28%, or the equivalent of about $800m for Musk's stake.
In the past, Musk has openly debated the use of free speech on Twitter and has posed the question of whether the platform is undermining democracy. He has also tweeted out many of his absurd ideas and shared the most radical thoughts on his Twitter, which have for the most part always caused controversy.
People had strong reactions to the value hike.
"Tell me why capitalism is broken without telling me. It’s still the best system to build wealth but acknowledging its flaws is also ok," wrote one person.
Tell me why capitalism is broken without telling me. It\u2019s still the best system to build wealth but acknowledging its flaws is also ok