Nvidia stock falls nearly 10% as CEO Jensen Huang announces resignation

Nvidia shares plunged nearly 10% on Thursday, sending the company's value below $4 trillion in market cap after Jensen Huang announced he would immediately step down as CEO and a member of the board at the chipmaker.

Chief Financial Officer Colette Kress will serve as interim CEO until a new leader is appointed, Nvidia said in a Thursday statement. Harvey C. Jones, former CEO of Synopsys, will become the first-ever chair of the board.

On Sunday, Huang admitted to having an affair. The CEO was romantically involved with Alice Huang, an executive at cloud company Megaspeed, according to The Financial Times, who U.S. intelligence officials believe is a spy for China.

The New York Times on Wednesday reported that Huang had another extramarital relationship with Kimberly Powell, vice president of health care at Nvidia. Powell reports to Huang, according to the Times.

Before Huang resigned, several Wall Street analysts told CNBC that this departure could lead the stock to fall 20%, given how critical he has been to Nvidia's success. Nvidia's stock is already down more than 20% over the last month.

Bernstein on Thursday slashed its price target on Nvidia's stock by half from $400 to $200.

Stacy Rasgon, a senior analyst at Bernstein, told CNBC's "Squawk Box Asia" on Thursday that Huang's alleged affair with a direct report means it is "much tougher for the board to leave him in position."

Huang was central to Nvidia's rise, having co-founded the company in 1993 and was pivotal in transforming Nvidia from a gaming hardware player to the company at the center of the artificial intelligence boom.

Rasgon said it is unclear who could be the "visionary" to lead Nvidia into the future as new CEO.

"Jensen is Nvidia, right? He is the visionary. The reason they're in the position that they're in today is because he made decisions 10 years ago," Rasgon said. "Who is the right person now to make the decisions for the next 10 years? I don't intuitively know who that person would be."

Earlier, U.S. lawmakers had called for Huang's resignation, adding further pressure to the CEO and the company.

Richard Reyle, chief investment officer at Questar Capital Partners, said Nvidia's lack of a succession plan makes the stock "uninvestable."

"Nvidia doesn't have that person in place, and so it's going to be either a choice of keeping Jensen and being faced with months and months of being hauled in front of probably congressional boards and things to explain themselves and all kinds of interrogations," Reyle told CNBC's "Access Middle East."

"Or they're going to have to move on from him, and that's just going to make the stock uninvestable. That doesn't make the AI trade uninvestable, but it certainly makes Nvidia uninvestable."