Elon Musk on Monday became the first person ever worth $600 billion, Forbes said, on the heels of reports that his SpaceX (SPAX.PVT) ‌ startup was likely to go public at a valuation of $800 billion.

Musk, who ‌was the first to surpass $500 billion in net worth in October, owns an estimated 42% stake in SpaceX, which is preparing to go public next year, Reuters reported ⁠last week.

The SpaceX valuation ‌ would strengthen Musk's wealth by $168 billion to an estimated $677 billion as of 12 p.m. ‍ ET on Monday, according to Forbes.

Musk's wealth also got a boost from his roughly 12% stake in EV maker Tesla, shares of which have risen 13% so far this year, ‌despite flagging sales. They were up nearly 4% on Monday after Musk said the company was testing robotaxis without safety monitors in the front passenger seat.

In November, Tesla (TSLA)shareholders approved a $1 trillion pay plan for Musk, the ⁠largest corporate pay package in history, as investors endorsed his vision of morphing the EV maker into an AI and robotics juggernaut.

As well, his artificial-intelligence startup xAI ‍is in ⁠advanced talks to raise $15 billion in fresh equity at a valuation of $230 billion, according to a media report.