San Jose, CA – Federal investigators have launched a criminal antitrust investigation of the $12 billion computer memory chip industry, issuing subpoenas to at least seven companies.

Details of exactly what was under suspicion and who is being probed were not released, according to the Associated Press, leaving many observers wondering whether there is a valid reason for such a probe.

Legal experts said criminal antitrust investigations commonly focus on price-fixing or unusually blatant efforts among rivals to divide customers or markets. But they also cautioned that companies that receive subpoenas aren’t necessarily the targets of a US investigation.

Analysts say the memory chip industry has always seen wild price fluctuations. “If you would say these guys must be colluding, then it looks rather odd that prices would have gone up by three and then dropped in half,” said David Wu of Wedbush Morgan Securities. “So I don’t know what data you could use to support collusion.”

Korea’s Samsung Electronics Co., a maker of DRAM chips, Germany’s Infineon Technologies AG, Hynix Semiconductor Inc., and Idaho’s Micron Technology Inc. confirmed that they received subpoenas earlier this week.

The four companies described the US Department of Justice actions as part of an industrywide investigation and said they would cooperate.

The companies said they would cooperate fully with the investigation.

Additional media sources are reporting that at least seven companies are under investigation, including Winbond Electronics and Nanya Technologies, which have confirmed they had received subpoenas from US authorities.

Japan-based Elpida Memory also said its US sales division had received a subpoena in the probe, according to CNN. Elpida is a joint venture of NEC and Hitachi.