Subsidiaries for advertising companies Omnicom Group Inc (OMC.N) and Publicis Groupe SA (PUBP.PA) were subpoenaed by the U.S. Department of Justice, both companies said on Friday.
The Justice Department's antitrust division has been investigating whether ad agencies had rigged bids to favour in-house production units.
Both Omnicom and Publicis said they received the subpoenas on Wednesday.
Publicis did not disclose which subsidiary was subpoenaed and a representative for the company declined to provide any further information.
Omnicom said that two of its subsidiaries were subpoenaed, but did not disclose which companies. A representative for Omnicom declined to provide any further information.
Rival Interpublic Group of Cos (IPG.N) said earlier this month that one of its domestic agencies had been contacted by the DoJ as part of the investigation.
(Reporting by Tim Baysinger in New York and Aishwarya Venugopal in Bengaluru; Editing by Ted Kerr, Andrea Ricci and Bernard Orr)