Advertisers have reportedly begun shifting their spending patterns following Apple’s iOS update that requires apps to gain iPhone and iPad users’ permission to track them. Industry data shows that mobile advertising aimed at iPhone users has dropped significantly while advertising aimed at users of Google’s Android OS are climbing.

The Wall Street Journal reports that advertisers are shifting their spending patterns following the recent iOS update which requires users to specifically grant apps permission to track their browsing habits. The update was released in April and many Apple iOS users received a high volume of prompts from apps asking permission to track them — the majority of which have been declined.

According to the ad-measurement firm Branch Metrics Inc., less than 33 percent of iOS users opt in to tracking. This means that prices for mobile ads directed at iOS users have fallen, while ad prices have risen for advertisers aiming to target Android users. These shifts come after many in the advertising industry warned that Appel’s changes would limit advertisers’ access to data about consumers and would hurt their business.

Digital advertisers state that they have lost a huge amount of the data that made mobile ads on iOS devices effective and justified their prices. In recent months, ad-buyers have used their iOS ad budget in much less targeted ways than were previously possible. The shortage of user data to fuel Facebook’s suite of ad-targeting tools has also further reduced their effectiveness and appeal among some advertisers.

As more information on the effect of the iOS update has emerged, advertisers have adjusted their buying strategies. Spending on iOS mobile advertising has fallen by about one-third between June 1 and July 1, according to the ad-measurement firm Tenjin Inc. Android spending rose 10 percent over the same period, according to Tenjin.

The digital ad agency Tinuiti Inc. stated that its Facebook client sent from year-over-year spend growth of 46 percent for Android users in May to 64 percent in June. The clients’ iOS spending in comparison went from 42 percent growth in May to 25 percent in June.

Read more at the Wall Street Journal here.

Lucas Nolan is a reporter for Breitbart News covering issues of free speech and online censorship. Follow him on Twitter @LucasNolan or contact via secure email at the address lucasnolan@protonmail.com