Elon Musk bought a 9.2% stake in Twitter, amounting to $2.9 billion.
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Justin Bieber reached one million followers on Twitter.
Elon Musk announced that he was building a spaceship called Starship that would travel to Mars and return to Earth.
Twitter was launched to the public.
Space Exploration Technologies Corporation, more commonly known as SpaceX, was founded by Elon Musk.
Elon Musk revealed Tesla's first electric cyber truck with shatterproof windows.
