ByMatt Durot,

Forbes Staff.

The world’s richest person just hit another major milestone thanks to the soaring valuation of his rocket maker SpaceX.

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lon Musk just took another giant leap toward becoming the world’s first trillionaire. Earlier this month, Musk’s rocket maker SpaceX launched a tender offer valuing the firm at $800 billion, up from $400 billion in August, two of the company’s investors tell Forbes. That boosts the fortune of Musk, who owns an estimated 42% of SpaceX, by $168 billion to an estimated $677 billion as of 12 p.m. Eastern Monday. Musk is now the first person ever worth $600 billion or more. No one else has ever been worth $500 billion.