The US Department of Justice is investigating claims of anti-trust activity in the graphics chip and add-in card markets, it has emerged. AMD yesterday said it had been subpoena'd by the DoJ as a result of its acquisition of ATI.

The chip maker stressed the DoJ has not made any specific allegations against it or against ATI. It also said it would co-operate with the organisation's anti-trust investigators.

At this stage, it's not known what claims the DoJ is looking into. Usually this kind of probe centres on attempts to fix prices. It's possible an ATI or AMD rival has alleged foul play in relation to the two companies' merger, announced in June and completed in October, but since the acquisition was cleared by regulators, that seems unlikely.

The DoJ is likely gathering information to allow it to judge whether the allegations made to it have sufficient merit to warrant a full-scale investigation.

Over the past few months the DoJ has supboena'd a number of SRAM manufacturers, part of a investigation into price-fixing allegations made against a number of market participants. ®