China has launched an antitrust probe into chip giant Nvidia, a poster boy of the US tech industry, the State Administration of Market Regulation said on its official WeChat account on Monday night.

The antitrust investigation was related to the US-based company’s acquisition of Mellanox, an Israeli-American supplier of networking products, according to the administration’s statement.

Nvidia China has not yet commented publicly. It’s unclear whether the investigation covers its core businesses of graphic chips and artificial intelligence.

After the news was announced, Nvidia’s shares dropped over 2 percent in pre-market trading on Monday night. Fueled by a boom in the artificial intelligence sector, Nvidia’s market value had hit about US$3.5 trillion, surpassing Apple and Microsoft this year to rank No. 1 in the world.