The US Department of Justice (DoJ) escalated a probe into Nvidia, reportedly issuing a subpoena to the chipmaker as it looks to find evidence that it violated antitrust laws on its way to becoming the dominant supplier of AI processors.

Citing sources close to the investigation, Bloomberg reported DoJ has sent legally binding requests to Nvidia and other related companies to provide information, raising the chance it will soon raise a formal complaint. The US authority had previously sent optional questionnaires to Nvidia and related parties.

Nvidia is facing queries from the DoJ over concerns that the company attempted to make it difficult for companies to switch to different suppliers as well as imposing penalties on those that didn’t use its AI chips exclusively.

Bloomberg first reported news about the probe in June. Nvidia responded by stating its dominance is a result of the quality of its products, pointing to faster performance compared to competitors’ offerings.

News of the subpoena further impacted Nvidia’s share price, with the company’s value dropping by $279 billion in late trading on Tuesday, with stocks across the board impacted by an economic downturn.

Despite its recent misfortune, Nvidia has however still experienced a rapid rise in the past year which saw it crowned the world’s most valuable company for a brief period in June. It has been a major winner of increased spending in AI, and last week indicated it would benefit majorly at the back end of the year through the launch of its new Blackwell AI chip.

Separately, Nvidia joined a $100 million funding round in Tokyo-based startup Sakana AI, marking one of the company’s biggest investments in the country’s AI segment.