Elon Musk's $399-billion wealth, which helped him reclaim the title of the world's richest man, is made up mostly of his 13% stake in Tesla, accounting for $152 billion. His 42% stake in SpaceX is worth about $136 billion, according to Bloomberg, while his 33% xAI stake is worth $23.4 billion. He also has a $3.42 billion stake in Neuralink.