Elon Musk's xAI company recently completed a $6 billion Series C funding round, with a current valuation exceeding $40 billion. Musk is likely to remain the world's richest person for the next 30 years.

Among Musk's six companies, only Tesla is publicly traded, while the others are SpaceX, X (Twitter), Neuralink, The Boring Company, and xAI.

Tesla (valuation $1.5 trillion): Electric vehicles and clean energy

SpaceX (valuation $350 billion): Space transportation and exploration, satellite launches

X (Twitter) (valuation $44 billion): Social media platform

Neuralink (valuation $7 billion): Brain-machine interface

The Boring Company (valuation $5.7 billion): Underground tunnels to solve urban traffic congestion

xAI (valuation $4 billion): Artificial intelligence company