Built by Publishers, for Publishers: The Mantis Approach to Ad Tech
With too little visibility into where ad spend actually goes, programmatic advertising has long favoured intermediaries over content creators. Publishers are increasingly seeking ways to reclaim control, improve transparency, and ensure their inventory is treated—and priced—as a premium product.
That’s the context in which Mantis was created. Incubated within Reach, the UK’s largest national and regional news publisher, Mantis emerged from the frustrations of a commercial team facing the limitations of old-school programmatic. Instead of waiting on fixes from external ad tech vendors, Reach created its own solution—anchored in contextual intelligence, brand safety, and a curation model—which is now available to other publishers and advertisers.
Terry Hornsby has been at the centre of that journey. With more than two decades in digital publishing at Reach—spanning roles in product, strategy, and innovation—he’s seen how ad tech has evolved, and where it’s fallen short.
We spoke with Terry about how Mantis is working to change that—from its origins inside a major media group to its growing role in making programmatic cleaner, smarter, and more valuable for publishers.
What's driving the growing interest among publishers in curation within the programmatic ecosystem?
"Publishers are increasingly drawn to curation as a means of reclaiming control over their inventory and driving better value in programmatic advertising. Traditionally, publishers have given multiple intermediaries access to their inventory, often with little visibility into how it’s being resold or valued. With transparency concerns growing across both the buy and sell sides, curation provides a structured way for publishers to present their inventory in a controlled, premium environment.
“Buyers also face challenges in the open programmatic market. Advertisers want brand-safe, high-quality environments but often struggle to differentiate meaningful inventory from generic offerings.
“Curation helps address this by allowing publishers to enrich their inventory with data layers that improve targeting and campaign effectiveness, ensuring buyers get quality impressions while publishers retain fair value for their content.”
How can publishers ensure their inventory is being represented properly when working with curation partners?
“The first step for publishers is to understand who has access to their inventory and how it is being packaged. A simple check within their ad server can reveal which partners are curating their supply. Beyond that, publishers should actively engage with their SSPs and curation partners to ask key questions: Who is curating my inventory? What value are they adding? How is my inventory being presented to buyers?
“A good curation partner should be transparent about their methodology, whether they are layering in additional data signals or simply repackaging supply without meaningful differentiation. The risk in the latter scenario is that publishers lose control while buyers pay a markup for what is essentially the same inventory.
“By ensuring their inventory is curated in a way that adds real value—whether through enhanced contextual targeting, brand safety measures, or audience segmentation—publishers can maintain a strong position in the marketplace.”
With concerns about transparency, what are other key questions publishers should be asking when their inventory is being included in curated marketplaces?
“Transparency remains one of the biggest concerns in programmatic advertising, and publishers should be asking direct questions to their curation partners to safeguard their inventory. In addition to ensuring they understand who is curating it and how it’s being presented, publishers should also be raising key questions such as:
What additional value is being provided beyond simple bundling of impressions?
Are there additional fees being taken from the process, and if so, where do they go?
What kind of reporting and visibility will I have into how my inventory is being sold?
How do advertisers perceive this curated inventory compared to direct deals or open RTB?
What does the future hold for curation in digital publishing? Will it eventually replace open RTB entirely or serve as a complementary approach?
“Open RTB is unlikely to disappear entirely, as it serves a key role in providing scale and efficiency, particularly for brands focused on reach and performance . However, it has long suffered from issues such as lack of transparency, brand safety risks, and commoditisation of inventory.
“Curation is emerging as a more structured, premium alternative, allowing publishers and advertisers to transact with greater confidence. That said, it will complement rather than replace open RTB.
“The future is likely to see a tiered approach, where premium, highly targeted inventory is accessed via curated marketplaces, while broader reach campaigns continue to rely on open programmatic channels.
“Ultimately, for curation to succeed, it must avoid the same pitfalls as open RTB. That means ensuring value is genuinely being added rather than just layering in additional costs. If done right, curation can offer a fairer and more transparent programmatic ecosystem where publishers and advertisers alike see tangible benefits.”
What advice would you give to publishers who are just starting to explore curation as part of their advertising strategy?
“For publishers new to curation, the key is to take an informed, proactive approach. Start by reviewing your current programmatic setup— again, who is accessing your inventory, and how is it being sold? From there, engage with potential curation partners, but be diligent in questioning what they bring to the table.
“Leverage industry groups like the IAB and AOP to stay informed, and don’t hesitate to consult with peers who have already navigated the curation landscape. Smaller publishers, in particular, may benefit from working closely with trusted SSPs to understand how their inventory is being packaged and sold.
“Finally, publishers should view curation as a way to enhance—not replace—their broader monetisation strategy. The goal should always be to maintain control over inventory, ensure fair value, and provide advertisers with high-quality, well-defined audience segments. Done correctly, curation provides the buy side with great controls and has the potential to create a more transparent and profitable future for digital publishing.”
As the programmatic ecosystem evolves, Mantis offers a blueprint for how publishers can take back control through transparency, leveraging tech, and insisting on real, measurable value. It’s also gratifying to see a publisher create a solution built by a publisher, for publishers—rooted in real-world needs rather than external agendas.