NVIDIA Shares fell 2% in premarket trading on Wednesday after Bloomberg reported that the company had received a subpoena from the Justice Department as part of an antitrust investigation.

The drop came after Nvidia fell nearly 10% in regular trading, wiping out $279 billion in market capitalization. The company’s stock then fell in after-hours trading and was down about 1.94% in premarket trading as of 4:32 a.m. ET on Wednesday.

According to Bloomberg, the US Justice Department’s investigation has not yet reached the stage of a formal complaint, and the agency is raising questions about whether Nvidia is making it harder to switch to other AI chip suppliers. Industry estimates suggest Nvidia holds more than 80% of the data center AI chip market.

Nvidia’s tremendous rise in recent years is directly attributable to its dominance in data center AI chips, which was established years before rivals AMD and Intel began taking the category seriously. Nearly a decade ago, Nvidia developed a programming language for its chips called CUDA, which is an important tool for engineers training advanced AI models like the one at the heart of ChatGPT.

Many of Nvidia’s top customers are cloud companies and internet giants, including Microsoft, Alphabet, Meta, Amazon and Tesla.

As Nvidia’s AI chips have become a hot commodity, the company has launched new enterprise software subscriptions and marketed its networking products as important complements to get the most out of its chips.

Current versions of Nvidia chips can be pre-installed in complete server racks designed by Nvidia – an example of Nvidia’s efforts to evolve from a mere parts supplier to a provider of complete systems.

An Nvidia spokesperson told CNBC that the company “wins based on performance, as reflected in our benchmark results and our value to customers, who can choose the solution that works best for them.” The Justice Department declined to comment to CNBC.