Why Display CPMs Fell in 2025 and How Publishers Can Protect Revenues in 2026

Key Takeaways

• UK digital ad spend up 10% in 2025, video outpaces display.
• Excess display inventory and static demand drove CPM slump.
• Viewability, ad load limits, and Core Web Vitals boost CPMs.
• First‑party data and contextual targeting improve audience value.
• Diversifying with video, native, and PMPs mitigates revenue risk.

Pulse Analysis

In 2025 the UK digital advertising market expanded by roughly 10%, driven largely by a surge in video spend, while display advertising struggled to keep pace. Generative AI tools have reshaped search behavior, pulling traffic away from traditional referral sources and flooding the market with excess display inventory. Despite this, the Association for Online Publishers reported that its members saw the strongest display revenue growth in three years, generating about £55 million (≈ $70 million) and even outpacing subscription earnings. The combination of static demand and abundant supply created the perfect storm for CPMs to tumble.

Publishers can arrest the decline by focusing on inventory quality. Improving viewability—through fixed‑position ad slots, reduced font sizes that slow scrolling, and limiting the number of ads per page—directly lifts CPMs while also satisfying Google’s Core Web Vitals. Simultaneously, robust first‑party data collection via newsletter sign‑ups, polls, and consent‑optimised walls enables richer contextual and identity‑based targeting, increasing bid‑stream value without breaching privacy regulations. A/B testing these changes provides measurable lift and informs ongoing optimisation.

A longer‑term safeguard is revenue diversification. Adding rich‑media, native and video formats spreads risk and opens new demand sources, while subscription programmes—like the £55 million (≈ $70 million) generated by AOP members—provide a stable cash base that can fund higher‑quality ad experiences. Private marketplaces allow publishers to sell premium inventory at negotiated rates, but they require careful curation to avoid cannibalising open‑programmatic sales. Partnering with ad‑tech specialists such as Refinery89 can supply the expertise and technology needed to manage PMPs, enrich audience data, and keep display a viable pillar of the 2026 commercial mix.