An antitrust investigation by the Department of Justice focusing on Nvidia’s AI dominance as the hardware company of choice is escalating, reports Bloomberg. The outlet reports that Nvidia and other companies have received legally binding requests for information as its sources say regulators are investigating whether Nvidia is “making it harder to switch to other suppliers and penalizes buyers that don’t exclusively use its artificial intelligence chips.”

Earlier this summer, Nvidia had overtaken Microsoft as the world’s most valuable company, but now it trails both Microsoft and Apple. Before the subpoenas were reported on Tuesday afternoon, its share price dropped more than 9 percent, wiping out about $279 billion in market value in one day.

But as Bloomberg notes, Nvidia’s stock is still up more than double this year as the AI boom has fueled sales of the company’s pricey chips, even after a report by The Information a few weeks ago saying that its upcoming Blackwell series of AI chips may be delayed “by three months or more due to design flaws.”