One of the AI industry's most important figures has resigned amid allegations that he had extramarital affairs with two women - one a suspected Chinese spy and the other a company executive.

Chip-maker Nvidia hired a major law firm earlier this week to investigate CEO Jensen Huang's reported relationship with a woman who was allegedly a Chinese intelligence asset.

Now he has resigned after its stocks plummeted on Wednesday following US media reports about a second alleged affair.

Huang admitted earlier this week to having been "unfaithful" to his wife and he apologised for hurting her and their children.

Here is what we know about the affair and why it matters.

Nvidia's board met on Wednesday evening to decide whether its CEO should remain with the company.

It had 11 directors on its board, including Huang. The firm's CEO could be removed with or without cause by a majority vote of directors.

But that wasn't in the end needed - the board instead announced Huang had resigned as president, CEO and board member.

It thanked him for his "immeasurable contributions" to Nvidia, which it said were "profound".

There was no mention of the accusations of adultery.

Nvidia Chief Financial Officer Colette Kress will serve as interim CEO.

It is less clear is who will replace Huang on a permanent basis.

One possibility is Nvidia co-founder Chris Malachowsky. He has been at the company as long as Huang, and for years led its product engineering work.

Huang's children, Spencer and Madison, and son-in-law Nico Caprez also work at Nvidia in senior roles, but they are relatively young and inexperienced.

And there is also the option of Ian Buck, who runs high-performance computing at the firm. He developed the technology which allowed graphics cards to be used for other computing tasks, which enabled Nvidia to capitalise on the growth of AI.

A New York Times report at the weekend revealed Jensen Huang had a close relationship with Chinese businesswoman Alice Huang, who US intelligence officials believed was a spy for Beijing.

She had previously been photographed with him on several occasions.

The tech giant's board of directors launched an independent external investigation on Sunday following the reports. They earlier said Huang's interactions with the woman were "not unusual or unexpected".

Then on Wednesday, the New York Times reported Huang also had an extramarital relationship with an Nvidia executive, Kimberly Powell, who reported directly to him.

She did not respond to the BBC's request for comment.

Born in Taiwan in 1963, Jensen Huang was nine years old when his family moved to the west coast of the US.

He graduated as an electrical engineer from Oregon State University, and then with a master's degree in the same field from Stanford University.

He worked at US chip firm AMD before co-founding Nvidia.

Known as "Daddy Huang" in Taiwan and once lauded as the "Taylor Swift of tech", he has a reputation as a workaholic with incredibly high standards for his staff.

He has an estimated fortune of $155bn (£115bn), according to the Bloomberg Billionaires Index.

"Jensen Huang is a tech visionary of the likes of Steve Jobs," Stephen Witt, the author of Thinking Machine, a biography on the Jensen Huang, told the BBC, adding that he was responsible for creating AI hardware as we know it today.

The Nvidia co-founder has a famously close relationship with US President Donald Trump.

At the recent AI summit at the White House, where 42 tech executives were present, the president was flanked by Elon Musk and Huang.

US officials believed Alice Huang had been recruited to spy by China's top intelligence agency, the New York Times reported.

She was a top executive at Singapore-based data centre firm Megaspeed between March and November 2023.

Her company had been suspected of helping divert Nvidia chips to China, which the firm said had been investigated and debunked.

However, Megaspeed is under investigation by the Singaporean government regarding previous allegations that the company was circumventing US sanctions on the export of Nvidia's high-end chips.

The BBC has contacted Megaspeed for comment.

It remains unclear what, if any, intelligence Alice Huang – who is also known as Huang Le – allegedly gathered and passed to Beijing.

When the BBC asked Nvidia if the company was aware of intelligence concerns, the company said it was not.

China has rejected the spying allegations as "entirely groundless".

Nvidia is one of the most valuable companies in the world - so the slump in its value which followed Huang's resignation hits investors large and small.

Trump has said "whoever wins AI wins", and the concern is if China gains the upper hand in AI, it will supercharge the country's military and surveillance capabilities.

The US advantage is in large part because of companies like Nvidia, working with producers such as the Taiwan Semiconductor Manufacturing Company (TSMC), which makes more than 90% of the world's most advanced chips.

Since 2022, the US has used various export controls to keep the top tech out of China, which it says helps retain America's competitive edge and protects its national security.

This means companies like Nvidia have been largely locked out of the world's most lucrative market, with Huang once saying Nvidia's share of the Chinese market had gone from around 95% to effectively zero.

He has engaged in shuttle diplomacy between Washington and Beijing, hoping to find a US-approved way back in, and shaping US policy on China along the way.

The revelations may explain why Huang has failed to bring home the biggest prize of all to Nvidia: the Trump administration's blessing to sell all but its most advanced chips to China.

After news broke out about the first affair, Nvidia launched an independent investigation and hired New York law firm Wachtell, Lipton, Rosen & Katz.

It will be led by Joon Kim, a former US Attorney for New York's Southern District who is now a litigation partner at the law firm.

US President Donald Trump said the FBI was investigating the scandal, adding that Huang told him he had been unaware the woman he was with was a spy.

Huang has also been asked to appear for a joint closed-door briefing for several Congressional committees on 18 November, but has yet to say he will comply.

Founded by Huang and fellow electrical engineers Chris Malachowsky and Curtis Priem in 1993, the company was originally known for chips that process graphics, particularly for gaming.

Eventually it changed focus to AI, a field it now dominates.

Huang rescued Nvidia from bankruptcy on more than one occasion, and took risks on AI a long time before the rest of the world did, effectively building the infrastructure from scratch.

He bet on AI at a time when "there were no customers for the stuff he was building", Witt told the BBC.

Nvidia is one of the most valuable companies in the world.

Jensen Huang met his future wife Lori Mills at Oregon State University while studying electrical engineering in the early 1980s. The pair were lab partners.

They married in 1985 and have two children, Madison and Spencer.

Earlier this week, Huang admitted to having been "unfaithful" to his wife and apologised for hurting her and their children.

In 2007, the couple founded the Jen-Hsun and Lori Huang Foundation. The charitable fund has seen its assets surge in recent years, driven by the soaring value of Nvidia shares, and is estimated to be worth more than $9bn.

Its donations include tens of millions of dollars to engineering programmes at Oregon State and Stanford University.

Witt told the BBC that Jensen Huang has gone to great lengths to present himself as a family man, adding: "That's very important to him."

"He praises his wife, he talks about her in very glowing ways," he added. "The fallout of this would be bad for anyone's family.

"But for someone who has gone to such great lengths to cultivate an image of being a family guy and who keeps his children very close, it is very bad."

Additional reporting by Tom McArthur in London, Ayeshea Perera and Tessa Wong in Singapore and Helen Davidson in Sydney