Facebook falsely reported ad performance on iPhones and iPads, blaming Apple’s policy changes to iOS, the company said in a blog post.
The social media company estimated that it had underreported third-quarter ad performance on iOS devices by 15%.
As a result, Facebook stocks were down over 2% on Wednesday, according to a CNBC report.
“Our estimate is that in aggregate we are underreporting iOS web conversions by approximately 15%; however there is a broad range for individual advertisers,” Facebook said.
“We believe that real world conversions, like sales and app installs, are higher than what is being reported for many advertisers.”
Apple’s update allowed iOS users to opt-out of being tracked when launching an application for the first time.
Facebook said tracking helps the social media platform and other apps deliver more customised adverts to users.
“We’re optimistic about our multi-year effort to develop new privacy-enhancing technologies that minimise the amount of personal information we process while still allowing us to show personalised ads and measure their effectiveness,” Facebook said.
The company outlined several actions that advertisers can take to understand their ad performance better, such as setting up the Conversions API and analysing the campaign instead of the creative.