Agency Buying Shift Pulls Radio Into Principal Media Model.

A fast-growing shift in how agencies buy and sell advertising may soon reshape not just where audio dollars flow, but how they’re classified, packaged, and priced. New research from the Association of National Advertisers shows principal media — where agencies purchase inventory and resell it to clients — is rapidly moving into the mainstream. More than half of marketers (58%) say they used principal-based buying in the past year, up from 47%, while 56% expect to use it in the year ahead.

At the center of that growth is a simple but powerful driver with pressure to move more spending into “working media.” The report finds increased management scrutiny is pushing procurement teams to prioritize dollars that appear to go directly into media, while reducing visible agency fees. Principal media helps accomplish that by bundling services into the cost of inventory, shifting more spending into the working media column even if total costs remain unchanged.

That dynamic is fueling adoption. ANA finds 76% of marketers cite reduced cost as the top benefit, with one respondent describing principal media as delivering “efficiency savings that can drop to the bottom line to help profitability or reinvested in media to help drive growth.”

For audio, the implications are mixed. On one hand, radio and podcasts stand to benefit from the industry’s push toward working media, as dollars shift away from fees and toward inventory. On the other, the report suggests audio is increasingly being absorbed into larger, agency-controlled deals rather than bought as a standalone channel.

The ANA data shows audio sits squarely in the middle tier of principal media activity as 38% of marketers say audio is part of their principal media mix — on par with out-of-home and just behind digital (43%) but well below television, which dominates at 74%. Audio is part of the mix, but it’s often bundled in as part of broader, multi-platform buys assembled by agencies.

For radio, which has long benefited from relationship-driven sales and a reputation for transparency, that shift cuts particularly deep. If inventory is increasingly bundled into principal deals, advertisers may have less visibility into where spots are running, how they were priced, and why they were selected. In some cases, decisions may be driven as much by agency margin opportunities as by campaign strategy.

The rapid rise of principal media also collides with a growing crisis of confidence among advertisers. The study finds 90% of marketers say their biggest concern is whether principal media recommendations are truly in their best interest. That reflects the core tension in the model — agencies are no longer acting solely as independent advisors, but also as sellers of inventory they own or control. As that line blurs, so does advertiser trust in the objectivity of media plans.

“Principal media is becoming a more common part of the media ecosystem, but marketers need to ensure they have the right safeguards in place,” ANA CEO Bob Liodice said. “Marketers should always understand whether their agency is acting as an agent or a principal in any media transaction.”

The concern isn’t just theoretical. The report also highlights broader transparency issues tied to principal media, including limited audit rights and reduced insight into agency markups. Even when performance data is available, marketers may not know what the agency paid for the inventory — making it harder to evaluate true value.

For radio sellers, that could create an opening. In an environment where advertisers are questioning who is acting in their best interest, the ability to offer clear pricing, direct relationships, and full transparency may become a more powerful competitive advantage than ever.