Nvidia's board has hired prominent US law firm Wachtell, Lipton, Rosen & Katz to conduct an independent investigation involving CEO Jensen Huang. The probe will be led by former acting Manhattan US Attorney Joon H. Kim, with no timeline announced for its completion. Meanwhile, three Republican committee chairs in Congress have asked Huang to attend a closed-door briefing on November 18, as scrutiny grows. US President Donald Trump has also said the FBI is looking into the matter.