• by Joe Mandese  @mp_joemandese, December 16, 2016

Omnicom is the second big agency holding company subpoenaed to testify as part of a U.S. Department of Justice antitrust investigation of video production and post-production practices in the advertising industry.

Omnicom confirmed that two of its subsidiaries received DOJ subpoenas, but did not disclose which ones they are. The holding company added that it is “fully cooperating with the investigation.”

Last week, the DOJ subpoenaed a unit of Interpublic Group, but the division was not disclosed.

The investigations are believed to be involved in "bid rigging" practices used by agencies to source work from independent producers.