The efficiency of the digital advertising market does not depend solely on advertisers' optimisations. Publishers must also actively participate in how their ad inventory is distributed and monetised. Demand Path Optimisation (DPO) is precisely that: the publisher examines their supply chain, makes conscious decisions, and influences the routes and conditions under which their inventory meets demand.
DPO reflects a broader trend in which the sell side no longer merely offers ad space but increasingly seeks to understand and control its value. It complements the traditional concept of Supply Path Optimisation (SPO), where advertisers optimise their buying paths by selecting the most efficient and high-quality routes to inventory. DPO shifts the perspective: it focuses on how publishers can direct delivery paths and influence business outcomes. The growing need to improve programmatic inventory quality, transparency, and control makes DPO more relevant now than ever.
Relevant Digital gathered insights from the leading independent SSPs (Supply-Side Platforms) on the type of inventory they prefer to receive and their expectations for the publisher’s role in managing delivery paths. This summary compiles the key findings and shows why active management is not just a good practice but a crucial competitive advantage in the evolving programmatic advertising ecosystem. Most SSPs wanted to answer anonymously, so we won't mention all the names in this report.
What SSPs Expect from Publishers in Demand Path Optimisation
SSPs’ responses highlight that the importance of Demand Path Optimisation (DPO) is widely understood, but no consistent practices have yet been established. All respondents believed that transparency, high-quality data, and broader visibility into inventory are key prerequisites for effective collaboration. At the same time, SSPs differed slightly in how actively they expect publishers to filter and optimise their supply before the auction.
Data Quality and Transparency Are Foundational
Every response emphasised the value of transparency and quality data. The more accurately the bid request describes the available inventory, the better it can be targeted and monetised. For example, Adform stressed that the data passed through should follow open standards and be as comprehensive as possible.
Particularly essential are user identifiers, such as device-specific IDs, such as device.ifa, which refers to a mobile device’s advertising identifier, and widely accepted identifiers like UID2 (Universal ID 2.0), an open alternative to third-party cookies. Also necessary is the accurate completion of technical fields in bid requests, including information such as the size and position of the ad placement and the user’s device and browser. Well-described and enriched inventory supports more effective monetisation and strengthens demand quality, benefiting both publishers and buyers.
Inventory Visibility vs. Pre-Auction Filtering
All SSPs participating in the survey valued having the broadest possible visibility into inventory. Full access to traffic enables more effective optimisation within their systems and can lead to improved performance. For instance, Magnite emphasised that they want to see every opportunity to optimise supply based on real-time demand using machine learning.
However, around 30% of respondents were open to publishers applying thoughtful pre-auction filtering, provided it’s done strategically and based on quality. Restricting supply by format, placement, domain, or performance metrics such as RPM (revenue per mille) created more intentional, targeted, and high-quality inventory.
The Role of Floor Prices in Optimisation
Several responses also raised the importance of floor prices. While publishers don’t always control floor prices in curated deals, they remain a vital lever in open auctions. Too high a price can reduce bid activity, while too low a floor can lower win rates and revenue. According to SSPs, effective floor price management is still key to fine-tuning monetisation.
In summary, SSPs’ expectations for publishers can be distilled into a few core practices: ensure your bid requests are as enriched and transparent as possible. Offer broad visibility into traffic when it supports monetisation, but use thoughtful filtering when it improves quality and efficiency. Manage floor prices actively in open auctions, and build partnerships with SSPs based on goals and data.
Inventory Management Is Key to Commercial Success
The responses from SSPs deliver a clear message: publishers who take an active role in managing their inventory can strengthen their position in the programmatic value chain and improve their commercial outcomes. High-quality, transparent, and enriched data enables more effective monetisation and supports demand growth.
At the same time, balance is essential. Most SSPs emphasise that they want complete visibility into the available supply and that broad inventory access and signal quality are more important than excessive pre-auction filtering. The role of DPO may be overstated in recent industry discussions, and practical solutions are often found through open dialogue, by recognising the strengths of one's supply and aligning practices collaboratively with SSP partners.
Practical steps for publishers:
- Enrich and document bid requests as thoroughly as possible.
- Provide broad inventory visibility to SSPs; filter only thoughtfully and based on quality.
- Manage floor prices actively in open auctions.
- Build data-driven, goal-oriented partnerships with SSPs.