By PubMatic's AgenticOS. PMG's Alli Buyer Cloud. Amazon DSP eating The Trade Desk's lunch on CTV. Three separate companies, three different architectures, one shared thesis: the traditional demand-side platform is charging too much for what it does.
That thesis just got its loudest proof point yet. On March 24, PubMatic announced a partnership with Untapped Growth Collective, a media buying collective representing 20 independent agencies, giving member shops direct access to AgenticOS, PubMatic's AI infrastructure running on NVIDIA GPUs. Early campaigns claim 40-50% lower supply chain costs and 30% lower eCPMs. (We covered those numbers and their caveats in our earlier analysis. This piece isn't about whether PubMatic's receipts check out. It's about what happens when three different players bet against the same layer at the same time.)
The SSP eats up
PubMatic's play is the most structurally aggressive. AgenticOS lets agencies submit campaign briefs in natural language to an LLM-powered interface. Specialized AI agents handle audience discovery, execution, and optimization. Campaigns run through PubMatic's Activate, a bidder built natively on the sell side. No DSP integration required.
"The legacy view of a supply chain within programmatic, where there is a buyer who logs into a DSP who connects to an SSP who connects to publishers on the back end, that supply chain is collapsing," said Harry Tong, director of sales engineering at PubMatic, in an Adweek exclusive. "SSP, DSP terms are already a bit obsolete."
Brendan Clifford, co-founder and managing partner at Untapped Growth, told Adweek that indie agencies can now "input a media plan into an LLM, such as Claude, and execute transactions directly with supply-side platforms bypassing traditional DSP layers."
Since launching AgenticOS in January, PubMatic says more than 250 agentic deals have been transacted and nearly 100 brands, agencies, and streamers have applied to its Agentic AI Acceleration Program, according to the company's press release.
Verdict: PubMatic is an SSP that decided the buy side was a feature, not a separate company. Whether that works at scale is unproven. But the architecture removes a fee layer, and the early numbers suggest someone's margin is getting redistributed.
The agency builds its own
PMG took the opposite approach. Instead of routing through someone else's platform, it built Alli Buyer Cloud, its own alternative to DSPs. According to a Digiday profile from March 17, Alli gives PMG clearing prices at the impression level, cutting supply chain intermediaries that traditionally take margin and obscure pricing. PMG has direct integrations with inventory pools including NBCUniversal, CBS Sports, and Universal.
"We are the antithesis of principal-based media buying," PMG founder and CEO George Popstefanov told Digiday. "Principal-based media buying is like having solar panels and wanting to work in the darkness."
PMG reportedly posted 38% revenue growth in 2024 while refusing principal-based media buying, a practice that has quietly subsidized holding company earnings for years.
Different from PubMatic, PMG isn't asking agencies to trust an SSP's infrastructure. It's saying: we built the pipe ourselves, we see every impression-level price, and we don't take a principal position. The DSP doesn't disappear here. It gets replaced by something the agency owns.
Verdict: this model only works if you're PMG-sized and can afford to build infrastructure. But it proves the demand exists for a DSP alternative, not just the supply.
The buyers shop around
Then there's the quiet erosion happening at The Trade Desk. A Digiday investigation published in mid-March, based on interviews with more than 10 ad executives, found advertisers are increasingly testing alternatives. Tom Wigley, director of digital at VCCP Media U.K., told Digiday that Amazon DSP is "front and center" because of its retail media and Prime Video combination. Tucker Matheson, co-founder at Markacy, said his team has moved spend toward direct buys and retail media networks because "we can prove better results given the nature of more tailored buys versus always-on programmatic."
The Trade Desk's revenue hit $2.9 billion in 2025 with 47% margins and $1.3 billion in cash, per their earnings. This isn't a company about to collapse. But features that used to require minimum spend thresholds are reportedly showing up in standard agreements now. Measurement credits are appearing with fewer strings attached.
One agency executive told Digiday that The Trade Desk threatened mid-contract rate increases when spending paced below target, then backed down when the agency threatened to move spend elsewhere.
Verdict: when a dominant DSP starts unlocking gated features to keep clients from leaving, the competitive pressure is real, even if the revenue line hasn't cracked yet.
What three arrows point to
Any one of these stories alone is a vendor squabble. All three happening in March 2026 suggests something structural.
The DSP layer historically justified its 10-20% platform fee through two things: aggregated demand and workflow tools. AI agents can replicate the workflow tools. Collectives like Untapped Growth can aggregate demand. PMG proves an agency can build its own pipes. And Amazon proves that a DSP with first-party commerce data makes a generic DSP's targeting look like guesswork.
Does this mean DSPs are dead? No. Holding companies with entrenched DSP relationships won't rip and replace overnight. But the long tail of independent agencies, the segment that never had preferential rates or dedicated DSP account teams, now has at least two viable alternatives that didn't exist 12 months ago.
The approximately $67 billion global programmatic marketplace, per PubMatic's estimate, is large enough that even a 5-10% shift in how indies route their spend would represent billions in fee revenue up for grabs. If PubMatic's claimed 40-50% cost reductions hold at scale (a big if), the ROI case for staying on a traditional DSP becomes a hard conversation for any independent agency CFO.
What to do Monday morning
If you're running programmatic at an independent agency, stop treating your DSP as a given. Run parallel tests: one campaign through your current DSP stack, one through PubMatic's AgenticOS or a direct SSP path. Compare eCPMs, total supply chain costs, and time-to-launch. If you're large enough, talk to PMG about how they structured Alli Buyer Cloud and whether elements of that model are replicable.
If you're at a DSP, start building the case for why your platform fee is worth it beyond workflow automation. Because the workflow part of the value proposition just got commoditized by a chatbot.
Mira Castellano covers ad tech for The Daily Vibe.
