Apple's newest iPhone software is starting to cost online publishers and ad companies money, according to industry reports published this week.

iOS 27, which came out in mid-September, began blocking a group of data and identity companies in the Safari browser without warning, AdExchanger reported. The list included LiveRamp, Permutive, Audigent and the Unified ID 2.0 program. It also included adsrvr.org, the domain The Trade Desk uses to serve ads.

Digiday reports that the early losses are now showing up. Aditude, which helps publishers sell ad space, said Safari on iPhones and iPads makes up 11.7% of the ads its customers show and 11.4% of their ad revenue. Among readers who had installed the update, what publishers earned per thousand ads fell 10.5%. Because only about 8% of users had updated, Aditude put the overall revenue hit at about 1% for now.

There has been one fix: Apple released an iOS 27.2 beta that removes The Trade Desk's domain from the block list, AdExchanger reported, but that version may not become the standard download for three or four weeks. Anyone who installs iOS 27 today will still block the company's ads.

Other identity companies, including LiveRamp and UID2, remain cut off, which matters because marketers rely on those tools to connect ads across streaming television, mobile phones and web traffic. AdExchanger also reported that Apple may be working on a much larger block list covering hundreds of vendors. Apple has not commented.

The timing is especially difficult, Digiday noted, because the fourth quarter is when advertising technology vendors and publishers make most of their money.

"It's not going to get better. I would say it's going to get worse," consultant Davide Rosamilia told Digiday.

What we know: iOS 27 blocks several tracking firms in Safari, and early data shows a 10.5% drop in ad earnings among updated readers.
What we don't: Whether Apple will expand the block list, and how big the losses will be once more people update.