More than 90 percent of U.S. users of the latest version of Apple’s mobile operating system are taking advantage of a new feature to block an application’s ability to track their activity on their phones. This is bad news for advertisers. According to research updated Saturday by Flurry, an analytics company owned by the Verizon Media Group, 96 percent of U.S. users of iOS 14.5 blocked app tracking using the new App Tracking Transparency feature. Worldwide, advertisers fared slightly better with 88 percent of users shutting down application tracking on their phones. App Tracking Transparency requires an iOS application to inform a user, through the use of dialog boxes, that the app wants to track activity across the phone’s user interface and gives a user the power to deny such access. Over the roughly two and half weeks since the release of iOS 14.5, Flurry found that the “opt-in” rate for U.S. users rose slightly from two to five percent, while worldwide, rates climbed from 11 to 13 percent. Either way, the rate isn’t good news for advertisers who depend on app tracking to more precisely target their ads.