What questions are the big Holdcos dodging about Principal Media?

What questions do we have about pricing and markup disclosure?

1. What was the actual wholesale price you paid for our media, and what markup did the advertiser pay on top of it? K2 Intelligence’s original ANA study found markups on principal transactions ranging from roughly 30% to 90%, and that range still gets cited.
2. What’s your actual take rate as a percentage of a client’s total media spend, not just the “savings” you claim to deliver? Agencies pitch principal media as a 10-15% cost-saving mechanism, but that framing obscures the dramatic profitability increase the agency enjoys on a specific account.
3. In programmatic, can you show us the actual winning bid price, not just a blended final CPM? Undisclosed programmatic models bundle the real closing price with margin and fees into one number, making arbitrage invisible by design — critics call the discretionary markup control inside DSPs the “magic markup button”.

What’s the deal with rebates and where is my money?

4. Do you still receive volume rebates, credits, or “non-product related income” from media owners tied to our spend — and do we get our share? A 2024 internal GroupM memo made public in litigation reportedly put GroupM’s principal media/rebate-adjacent revenue at over $1 billion annually, described internally as “non-product related income”.
5. Are you recreating the same rebate economics the 2016 ANA/K2 report exposed, just repackaged as “principal trading”? Industry voices argue direct cash rebates are technically restricted in the U.S. but agencies “got craftier” and moved the same economics into principal deals.

What about conflict of interest and margin steering?

6. Are you recommending this inventory because it’s genuinely best for our campaign, or because you already own it and need to move it? Former UM global media chief (and current Quad exec) Joshua Lowcock and others describe holdcos “blending” low-value inventory with a small quota of premium inventory before reselling it at a markup.
7. Is your principal trading desk (Xaxis, Apex, etc.) truly firewalled from the team that plans our campaign? Numerous sources and former employees dispute how clean that separation is across the industry more broadly.
8. Why have you quietly removed the word “agent” or “agency” from so many contracts? Holdcos are often stripping “agent” language from media contracts specifically because that legal status is incompatible with acting as principal seller.
9. Aren’t the agencies that practice Principal Media buying actually competing with their own clients (if the client doesn’t opt-in to Principal Media)? The agency makes more money off the Principal Buy and the clients that opt-in supposedly get better media pricing. Doesn’t that by definition mean that the agency is competing to deliver better performance for itself than for its clients that do not opt in?

What are the scale, client disclosure and governance issues with Principal Buying?

10. How much of your total revenue and profit now comes from principal media — and why will you tell investors but not us? Omnicom is reportedly the only holdco that references principal-based media explicitly in earnings materials; analysts estimate GroupM near $1B, Omnicom near $4B, and Publicis generating “more than 50% of their costs” from principal trading.
11. Do you have documented internal guidelines governing when and how principal media is used with our account — and can we see them? In the ANA’s 2026 follow-up study, only 57% of marketers said their agency guidelines address principal media at all, down from 62% in 2024, even as adoption keeps climbing.
12. What audit rights are we giving up by agreeing to principal media in our contract? ANA and multiple auditors flag loss of full audit rights, inventory-quality visibility, and pricing transparency as standard trade-offs marketers unknowingly accept.
13. Is a “true” principal risk model even what you’re selling, or is our own committed budget the capital at risk, not yours? Critics argue that genuine principal risk requires the agency’s own capital exposed to loss — many holdco models are believed to use client volume commitments with no real agency-side downside, yet are marketed as “principal”.

Where is it spreading next?

14. Is there a medium where this isn’t happening? Reporting shows principal arbitrage expanding well beyond digital display and linear TV, to many other channels like DOOH and retail media as holdcos chase Principal Buying scale. Similar practices have already spread to data arbitrage (agencies marking up data charges in a non-transparent fashion) and are making their way to AI tokens.
15. Given the scale of the big three, will consolidated buying scale be used to negotiate exclusive deals that funnel even more inventory into the agency’s principal book rather than get advertisers the best open-market price? Consultants argue the “Big Three” are increasingly negotiating exclusive media deals specifically to feed reselling operations.

What’s the most important question of all?

16. Where is the beef? IE, is there any evidence at all, anywhere, that this practice is good for an advertiser’s business?
    There is a common thread with Principal Media: holdcos will confirm principal media exists and even tout it to investors as a growth engine for the agency, but they will not disclose the details that might call the practice into question (quantifying the specific markup, disclosing wholesale costs, or opening the books to audit on any individual account).
    
    Without more transparency, it’s fair for advertisers to assume they’re subsidizing agency margin with their own media budget.