NEW YORK - Mr Elon Musk has denied he had an affair with the wife of Google co-founder Sergey Brin, which the Wall Street Journal (WSJ) said led to a falling out between the two tech billionaires and long-time friends.

Mr Brin, who helped support carmaker Tesla - co-founded by Mr Musk - during the 2008 financial crisis, instructed his advisers to sell his personal investments in the latter’s companies in recent months, the WSJ reported, citing unidentified people familiar with the matter.

Mr Brin, 48, filed for divorce citing “irreconcilable differences” with Ms Nicole Shanahan, 37, after being married for over three years, the WSJ said, quoting court records.

However, in a tweet on Monday (July 25) , Mr Musk wrote: “Sergey and I are friends and were at a party together last night! I’ve only seen Nicole twice in three years, both times with many other people around. Nothing romantic.”

He also sent The New York Post a photo showing him partying with Mr Brin. 

The report has brought further focus on the 52-year-old’s personal life, just weeks after another report said he fathered twins with a top executive at his company.

Mr Musk, the world’s richest man with an estimated fortune of US$240 billion (S$332.3 billion), often spent time at Mr Brin’s place, according to the WSJ.

It reported that Mr Musk had an alleged liaison with Ms Shanahan, a California-based attorney and Silicon Valley entrepreneur, in early December in Miami, Florida. At that time, Ms Shanahan was separated from Mr Brin but still living together, according to a person close to her.

A month later, Mr Brin, who is estimated to have a net worth of US$95 billion, filed for divorce.

The WSJ claimed that although he listed ‘irreconcilable differences’’ as the reason, it was the affair that resulted in the divorce.

They are currently negotiating a settlement, with Ms Shanahan seeking more than US$1 billion, the WSJ said, even though there is a prenuptial agreement. 

They reportedly met at a yoga retreat in 2015 and it is the second marriage for both. They have a three-year-old daughter.

The alleged affair has also thrust Ms Shanahan, the daughter of a Chinese immigrant mother, into the limelight.

The Daily Mail reported that Ms Shanahan grew up in the San Francisco Bay Area, living off food stamps and trying to help her parents, before becoming a lawyer.

Ms Shanahan, in an interview to Modern Luxury magazine cited by the Daily Mail, said she faced many challenges growing up.

“As a kid, I really had to figure out how the world works on my own,” she said. “My dad was diagnosed with bipolar schizophrenia when I was nine, and my Chinese mom had only been in the US for two years when I was born.”

“And as you can imagine with a mentally ill father, there was a lot of chaos and fear."

Ms Shanahan graduated from the University of Puget Sound in Washington state in economics, Asian studies and Mandarin. She did her law degree at Santa Clara University and was an exchange student at the National University of Singapore in 2013.

She founded ClearAccessIP, a patent-valuation and management company in 2013 and has in the last few years been involved in philanthropy.

In 2019, she founded the Bia-Echo Foundation and gave US$100 million to social programmes for fertility and climate change.

According to the foundation’s website, she is a research fellow at CodeX, the Stanford Centre for Legal Informatics.

Her LinkedIn page lists her areas of interests as “criminal justice reform, and improving marriage contracts such that they promote healthy domestic partnerships”.

Mr Musk, the father of nine children, has been rarely out of the spotlight in recent months - either due to his personal life or his business dealings.

He is currently in a court fight to withdraw his US$44 billion bid for Twitter.

On the personal front, Business Insider reported in July that he had fathered twins with Ms Shivon Zilis, a 36-year-old top executive at his brain-chip start-up Neuralink, in November 2021. 

In another case, Mr Musk’s 18-year-old daughter Vivian Jenna, whom he shares with his former wife Justine Wilson, filed a petition in court to change her surname from Musk to Wilson, which was granted by the judge.

The billionaire also recently denied that he sexually harassed a flight attendant in 2016.