Apple's Safari tracking block: early losses tallied

Apple's latest Safari update cut off major cross-site trackers from operating in the browser, and a week on, publishers are starting to count the damage. Aditude, which helps publishers sell their ad space, reports Safari on iPhone and iPad accounts for 11.7% of the ads its customers serve and 11.4% of their ad revenue, and among readers who installed the update, eCPMs fell 10.5%. Because only about 8% of users have upgraded, Aditude puts the overall revenue hit at roughly 1% so far. The block arrived without warning, runs off a list few outside Apple see, and landed at the start of Q4, when ad tech vendors and publishers make most of their money. Index Exchange CEO Andrew Casale, largely unaffected because his company is not in the identity business, still called the move "an invasive overreach" that holds the web to a different standard than apps. Consultant Davide Rosamilia is blunter: "It's not going to get better. I would say it's going to get worse." However, suspicion is hard to verify: one source told Digiday the IAB Tech Lab has tried to engage Apple on its privacy policies since the late 2010s and got little in return, and almost every source said not much has changed since.

The crux

Apple is using its control of the browser to squeeze the cross-site identity plumbing that open-web programmatic yield depends on, and the publishers most exposed are those without direct-sold inventory to fall back on.

Sell-side read

Publishers with heavy programmatic reliance on Safari traffic should model a 10% eCPM haircut on updated iOS inventory now and stress-test which of their vendors could land on Apple's list; direct-sold and subscription inventory is the hedge.

Watch

Whether Apple's blocklist expands beyond identity vendors to ad servers and SSPs, and whether The Trade Desk's ad server stays off the list past the end of the month.