AMD said it was contacted by someone in December who claimed to be in possession of test files related to a subset of its current and future graphics products. Some of these files were recently posted online, although they have been taken down since then, AMD said.
The perpetrator has additional files that haven't been made public yet, according to the company.
AMD said it does not think the individual has any other AMD IP.
AMD said the stolen graphics IP isn't core to the competitiveness or security of its graphics products.
"We are working closely with law enforcement officials and other experts as a part of an ongoing criminal investigation," AMD said in the statement.
The stolen details may have been related to the code for Navi graphics cards and the Xbox Series X custom GPU built by AMD, Tech Radar reported.
The hacker apparently obtained the source code from an unprotected computer/server, Torrent Freak reported.
While acknowledging that one source packet has already been released, the hacker said it could be valued at $100 million, according to the report.
"If I get no buyer I will just leak everything," Torrent Freak quoted the alleged leaker as saying.