Former Nvidia chief executive Jensen Huang has been summoned to testify before the United States Congress in December, days after he resigned from the chipmaker. The Senate Banking Committee has asked him to appear on 3 December, while three House committees want a closed-door interview on 1 December, and both have warned of subpoenas if he refuses to cooperate.

At the centre of the inquiry is Huang's reported relationship with Alice Huang, a businesswoman and former executive at the Singapore firm Megaspeed, a Nvidia customer. US media have reported that American intelligence believes she is a Chinese spy, an allegation China has rejected as a smear. The US Justice Department says it is investigating and has reached no conclusion.

What are the dates for Huang's testimony?

Senate Banking Committee chairman Tim Scott sent letters on Thursday 12 November asking Huang to testify voluntarily on 3 December and Commerce Secretary Howard Lutnick on 10 December, warning that the committee would use all tools at its disposal, including subpoenas. The three House committees — foreign affairs, intelligence and the select committee on China — have asked Huang to sit for a closed-door transcribed interview on 1 December, with Nvidia general counsel Tim Teter due the following day. House Foreign Affairs chairman Brian Mast said Huang had agreed to brief lawmakers before Thanksgiving, so an appearance could come sooner.

What do lawmakers want to know?

Congress wants to know what Nvidia knew about the alleged relationship, whether sensitive American technology or company secrets were exposed, and whether the company's security protocols were strong enough. Lutnick faces separate questions about exports of advanced Nvidia AI chips to China. Democrats have also opened an investigation into Nvidia's China sales, and Senator Elizabeth Warren said Huang's resignation "does not absolve him" of responsibility for any risk to national security.

What happens next?

Huang, who co-founded Nvidia in 1993, resigned on 12 November after admitting on Sunday that he had been "unfaithful" to his wife. Reports also link him to a second relationship with Kimberly Powell, a senior Nvidia employee. Chief financial officer Colette Kress has been named interim chief executive, and Nvidia reports third-quarter results on 17 November. The company has lost $550 billion in stock market value in five days as the scandal has dominated headlines. Huang has not been charged with any offence, and the allegations against him remain unproven.