WPP Says Safari Block Spares It as IAB Tech Lab Pushes Alternative
The Development
Apple's WebKit changes to Safari are cutting into the techniques advertisers use to recognise the same person across sites and devices, and parts of the ad industry are absorbing the damage. On WPP's third-quarter earnings call, CEO Cindy Rose said the block "doesn't really impact our data solution at all because we don't rely solely on identity matching." Richard Kramer of Arete Research had pressed her on exposure. Digiday framed the remark as a fresh case for InfoSum, the data collaboration platform tied to WPP's data strategy. A day earlier, IAB Tech Lab COO and EVP Product Shailley Singh published a post arguing there is one practical path forward for advertising and that other responses to the WebKit changes will not work.
Our Take
Rose's answer is half strategy, half reassurance for investors. "Not solely" does real work in that sentence: WPP is conceding identity matching is a component while claiming the product doesn't depend on it. We take the architectural point seriously, because clean-room collaboration is where this market is heading. But a holdco's data offering is only as resilient as the first-party data feeding it, and that sits with clients, not WPP. Meanwhile, IAB Tech Lab's "only practical path" framing signals the industry is converging on a standard response. Expect every holdco to claim insulation within a quarter. Few will be able to show it in client measurement results.
What Changed
The viable identity layer is moving from cross-site tracking signals to privacy-preserving data collaboration, where first-party datasets are matched and analysed in place without exchanging user-level identifiers. Safari's block makes that architecture a requirement for cross-publisher audience and measurement work, not an optional upgrade.
Marketing Impact
Media and measurement teams running Safari audiences should expect degraded reach, frequency and attribution fidelity where campaigns rely on cross-site matching. Data and martech leads need to audit which audience products and attribution models depend on identifiers Safari now blocks, and shift priority toward first-party and clean-room workflows.
Competitive Implication
Holdcos and vendors with privacy-preserving collaboration infrastructure gain a pitch advantage over identity-graph providers and ad-tech intermediaries whose products rest on cross-site matching. Those intermediaries are most exposed, since their core asset is the technique Apple is shutting down. Advertisers with strong first-party data gain leverage over every partner.
Strategic Outlook
Holdcos will push clean-room and data collaboration offerings harder through Q1 2027, and IAB Tech Lab's position will shape the standards debate. Expect identity-dependent vendors to reposition or consolidate. Claims of insulation will be tested when clients compare Safari campaign measurement against pre-block baselines.
The Exploit
Action Item
Heads of media and data should demand, before Q1 2027 planning closes, that WPP and every other agency partner show Safari-segmented measurement results with and without identity matching, then redirect budget toward partners who can prove performance.