The founder and chief investment officer of Chicago-based Valor Equity Partners is the second biggest beneficiary of SpaceX's stock market debut, only to Musk himself when he hit the trillion dollars mark, the first in the world to achieve so.

Gracias' net worth reached $24.4 billion as of Monday, according to the Bloomberg Billionaires Index, which valued his fortune for the first time. The surge was driven largely by Valor's SpaceX holdings, which were worth nearly $97 billion at the close of trading.

Gracias owns more than 500 million SpaceX shares through investment firms affiliated with Valor Equity Partners, representing about 7.3% of the company's Class A stock, according to Business Insider.

"It's a tremendous milestone, and I'm feeling a lot of gratitude," Gracias told CNBC shortly before SpaceX shares began trading. "I think it's one of the most consequential companies in the human industry."

Gracias also said last week that he intends to hold his stake "as long as possible."

Antonio Gracias, founder of Chicago-based Valor Equity Partners

The billionaire investor's relationship with Musk dates back more than two decades. The two met through Silicon Valley's technology circles in the early 2000s and quickly developed a close friendship.

Gracias lent Musk $1 million during Tesla's early years when the electric vehicle maker was struggling financially and facing the risk of collapse, Fortune magazine reported.

The friendship grew beyond business. Gracias served as a groomsman at Musk's younger brother Kimbal Musk's wedding, and the two families have vacationed and spent holidays together. They have also traveled together to magician David Copperfield's private island in the Bahamas.

Over the years, Gracias has backed nearly every major Musk venture. He has served on the boards of Tesla, SpaceX, SolarCity, Neuralink and The Boring Company. At Tesla, he spent eight years as lead independent director, while Valor Equity Partners became one of the company's earliest institutional investors.

More recently, Gracias followed Musk into government service, joining the Department of Government Efficiency. He resigned in July amid scrutiny over his management of $2 billion in public pension assets while serving as a government employee.