The Trade Desk has integrated its first Dutch publisher — Amsterdam-based publishing house Massarius — into OpenPath, its direct pipe that lets the DSP buy publisher inventory without the usual chain of intermediaries, per reporting on June 29, 2026. It’s a small deal with a big subtext: OpenPath’s continued European march (after Germany) keeps alive the industry’s most uncomfortable question — how much of every ad dollar actually reaches the publisher, and how much gets skimmed on the way.
01The supply-path pitch, and the fee it charges
OpenPath’s premise is disintermediation: shorten the distance between buyer and publisher, cut the hidden hops, and let more of the media dollar land where the content is. The Massarius write-up cites research that 42–49% of ad dollars fail to reach publishers through conventional supply chains — the “ad-tech tax” that direct paths promise to shrink.
But OpenPath isn’t free. It charges publishers a flat 4.5% fee, which Trade Desk CEO Jeff Green has described as “nearly breakeven to slightly profitable.” That fee — and the transparency around it — has become contentious. Dentsu and WPP quietly exited OpenPath in February 2026 over fee and transparency concerns, and a Publicis dispute was reportedly resolved in mid-June. A path sold as the transparent alternative is now having its own transparency debate.
02Why this matters
Every supply-path story is ultimately a story about your margin.
| Direct paths can genuinely mean more revenue | If nearly half the ad dollar leaks out in conventional chains, a shorter path with a known 4.5% fee can put materially more money in the publisher's pocket — provided the fee really is the whole cost. |
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| "Transparent" is a claim, not a guarantee | Holdco exits over transparency concerns are a reminder to interrogate every path — including the ones marketed as clean. Know exactly what you pay and what you get for it. |
| Concentration risk cuts both ways | Leaning into a single DSP's direct pipe can boost yield, but it also hands one buyer more control over your demand. Diversification of supply paths is as important as diversification of demand. |
The Massarius deal is minor on its own, but it keeps a major theme in play: the fight to shorten the programmatic supply chain is also a fight over who sets the toll on it.
03What publishers should do
04What marketers should do
05The bottom line
The Massarius deal is minor on its own, but it keeps a major theme in play: the fight to shorten the programmatic supply chain is also a fight over who sets the toll on it. Direct paths like OpenPath can put more of the ad dollar back in publishers’ hands — but only if the fee is transparent and the path is one of several, not the only one. Treat “direct” as a math problem to verify, not a promise to trust.