Stagwell’s Curate launch: 3 reasons agencies are building their own ad marketplaces

For brands and media buyers, every dollar wasted on poorly executed programmatic inventory is a direct hit to campaign ROI. Stagwell Curate is a direct answer to that pain point — offering a vetted pool of ad supply that strips out made-for-advertising junk and brand-unsafe placements. As more holdcos erect similar curated walls, marketers must reconsider their media strategies and partnerships to capitalize on more transparent, high-performing inventory paths.

Stagwell’s launch of Curate, a curated inventory marketplace, marks a pivotal moment in the ongoing power struggle over the digital advertising supply chain. Announced earlier this month, Curate is not a replacement for demand-side platforms (DSPs) or supply-side platforms (SSPs) — at least according to Matt Adams, global CEO of Stagwell Media Platform. Instead, it is a central, vetted reservoir of programmatic inventory designed to purge poorly executed ad placements from clients’ media spend. ‘There’s so much inventory that is still terribly executed within the programmatic ecosystem. We need to eradicate that from our client’s media spend,’ Adams told the Digiday Podcast. This defensive posture — positioning Curate as a filter rather than a challenger to established ad tech — belies a larger, industry-wide realignment.

“

Announced earlier this month, Curate is not a replacement for demand-side platforms (DSPs) or supply-side platforms (SSPs) — at least according to Matt Adams, global CEO of Stagwell Media Platform.

The programmatic ecosystem has long been dominated by a handful of technology giants. Google’s ad stack and The Trade Desk’s DSP wield enormous influence, while SSPs like Magnite and PubMatic manage the supply side. But agencies, which sit between brands and these platforms, have grown frustrated with opaque fees, brand safety failures, and the sheer volume of wasted impressions. Stagwell’s move is the latest salvo in a proxy war: agencies are building their own infrastructure not to compete head-on with DSPs, but to reclaim control over the quality and economics of the inventory their clients buy. This mirrors Publicis Groupe’s planned acquisition of LiveRamp, which aims to give the holdco a proprietary identity and data backbone, and The Trade Desk’s OpenPath initiative, which attempts to bypass SSPs and connect directly to publishers.

Adams acknowledges that building a superior DSP is a ‘naive ambition.’ The real opportunity lies in the ‘middle layer’ — the opaque, often duplicative routing of impressions through multiple intermediaries. By curating supply, Stagwell effectively short-circuits that layer for its own clients, promising higher viewability, fewer made-for-advertising (MFA) sites, and better performance. This is a direct response to client demands for transparency and efficiency. As digital ad spending continues to swell — global programmatic spend is projected to exceed $700 billion by the end of the decade — even fractional savings translate into significant client gains.

However, the agency-as-platform model raises critical questions. Will agencies’ curated marketplaces truly remain walled gardens, or will they eventually seek to interoperate and scale beyond their own client bases? If every major holdco builds its own inventory lake, the market risks fragmentation, complicating cross-platform measurement and frequency capping. Moreover, the DSPs are unlikely to cede ground without a fight. The Trade Desk’s OpenPath has already been perceived as a direct threat to SSPs; a stronghold of agency-owned supply could push DSPs to develop their own curation layers or further tighten integration with premium publishers. The result may be a more tiered ecosystem: top-tier curated marketplaces for premium, fraud-free inventory, and a commoditized long tail for everything else.

AI is poised to accelerate this bifurcation. Adams argues that as AI platforms democratize parts of the supply chain, the ‘cream will rise to the top’ while ‘those that are in the middle of the middle’ will fall away. Generative AI can automate creative versioning and media buying, but it also enables more sophisticated fraud detection and supply-path optimization. Curate’s value proposition — pre-vetted inventory — aligns well with the AI era, where algorithms can rapidly surface the most performant and brand-safe placements from a controlled pool. Stagwell is betting that its data and media planning prowess, combined with curated supply, will be a durable differentiator.