Agency groups are disputing claims in a new report from the Association of National Advertisers that they're collecting rebates, including "cash rebates," and that "other non-transparent practices" are pervasive in the U.S., at least within their own organizations.

The 58-page report is the product of an eight-month-long investigation conducted by independent firm K2 Intelligence for the ANA.

Here are a few holding company and agency responses -- some in thier entirety and some shortened -- to this morning's news:

WPP media agency network GroupM:
"The ANA report and the objectivity of its authors and advisors needs to be examined carefully. The report should not be allowed to tarnish the entire industry, nor every company in it. As we stated from the outset of the ANA's exploration, GroupM does not seek, nor accept, rebates or hidden revenues in any form from media partners in the U.S. Nor do we accept service fees from vendors that are not disclosed to clients. GroupM is straightforward with clients concerning our proprietary media products and the value they provide; clients always exercise an informed opt-in to participate. As we've already indicated, we insist that the ANA share any specifics relating to our group with us so that we can ensure continuing contract compliance. If clients have any questions, they should contact us."

Publicis Groupe:
"Had the ANA been willing to have an open dialogue with our industry, we would have been immediately ready to cooperate, as we did last year, and that is reflected in our engagement with the 4A's. By refusing such a dialogue and choosing a sensational approach, it seems clear that the ANA is not trying to find a solution to the alleged problems, and instead is acting with other goals in mind. The ANA has failed its members, advertisers, agencies and the entire industry by releasing a report that relies on allegations about situations involving unnamed companies and individuals to make broad, unsubstantiated and unverifiable assertions."

Interpublic Group of Cos., the lone major holding company to speak with investigators:
"IPG has been a leader in terms of media transparency since 2005, when we proactively confronted the types of non-transparent practices raised in today's ANA report. We eliminated these practices from our organization, issued public disclosures, and strengthened our governance controls. Since that time, we have continued to modernize our transparency practices for an increasingly digital and complex media landscape. Here at IPG we do not accept rebates in the U.S., nor do we believe rebates should be part of U.S. market practices. Additionally, IPG does not buy 'inventory media,' where we pre-purchase media on our own account and re-sell it to clients – this decision has been a point of differentiation for our company. As a result, we have a high degree of clarity in our contracts with clients and media owners regarding our respective roles and interests. Our practices have been reviewed in numerous audits conducted at clients' requests by a variety of firms, including ones that participated in creating the ANA report, and we are very proud of our track record. The broad and anonymous nature of the report's allegations is unfortunate and inflammatory. The picture the report describes is not consistent with our actual business practices."

Omnicom:
"We have not yet had a chance to fully review the ANA study, however based on the overview provided in the press release we believe that the key findings -- neither quantified nor qualified, and based on a small sampling of unnamed sources -- do not accurately portray how Omnicom's agencies work on behalf of our clients; in so doing, it does not serve the best interests of the clients that the ANA purports to represent. As we have said since the ANA first launched its study last year, we believe that trust and disclosure are the cornerstone of every client relationship. This means that all of our U.S. media agency clients receive all value negotiated on their behalf in the form it is received. Compliance with each individual client contract has always been central to that trust at Omnicom -- as is transparency in the structure and execution of each contract."

"We also offer proprietary opt-in services that provide certain benefits to clients. These are openly disclosed, discussed and agreed upon by clients who understand the value and choose to participate. These services remain separate and apart from our agency media buying teams. Omnicom takes seriously its obligations to investigate and appropriately redress any credible allegation of misconduct by its companies or personnel. Our outside legal counsel has asked the ANA, K2 and Ebiquity to provide specifics on any information their investigation has uncovered relating to Omnicom agencies and they have provided none. We take seriously our responsibility as an industry leader to address any issues that impact the ethics and standards of our industry as a whole -- and to that end we continue to both support and be actively involved in the leadership efforts to establish media industry standards."

"We encourage our clients who have any questions to contact us directly."