The world's biggest advertising holding companies have been cleared after a 2-year DOJ investigation into their business practices

REUTERS / Jonathan Ernst

• Omnicom, Publicis, WPP, MDC Partners, and Interpublic Group are no longer under investigation by the Department of Justice.
• According to reports and SEC filings, the companies were notified that they had been cleared in a two-year investigation into practices like rebates and media production.

After a two-year investigation from the Department of Justice into the production processes of advertising agencies, five of the world's biggest holding companies have reportedly been cleared.

Federal prosecutors were specifically looking into "non-transparent" practices like receiving rebates from media outlets. Five holding companies had received subpoenas as part of the investigation: WPP, Omnicom, Publicis, Interpublic Group, and MDC Partners.

According to reports from Adweek and AdAge, all five holding companies have been cleared in the investigation.

Omnicom and MDC Partners each put out SEC filings today with information to investors about updates to the investigation.

"As previously reported by Omnicom Group Inc. (the 'company'), two of the company's subsidiaries received subpoenas in December 2016 from the Antitrust Division of the U.S. Department of Justice (the 'division') concerning its investigation of video production and post-production practices in the advertising industry," Omnicom's filing says. "The company received confirmation from the division that its investigation of the company's subsidiaries has been closed without any action taken against the company, its subsidiaries or employees."

Over the past two years, the practice of non-transparent media buying has ballooned into a massive issue for the advertising industry after a 2016 bombshell report from the Association of National Advertisers revealed that such practices were "pervasive" in the US but didn't name specific agencies.