New Delhi: The Apple iOS privacy changes have cost social media platforms like Facebook, Snapchat, Twitter and YouTube over $9.85 billion in revenue in the second half of this year. An investigation by The Financial Times found that Snapchat, Facebook, Twitter, and YouTube lost around $9.85 billion in revenue after Apple introduced App Tracking Transparency (ATT) policy last year. Advertisement technology company Lotame estimated that the four tech platforms lost 12 per cent of revenue in the third and fourth quarters, which roughly translates into $9.85 billion. The new iOS App Store policy requires apps to ask permission to track users' data. The policy went into effect in April, barring apps from tracking users if they opt out. According to the report, Facebook lost the most money "in absolute terms" when compared to other social platforms due to its huge size. "Facebook has the most to lose because the cost of running advertisements on its platform has been increasing for years," the report said on Sunday. Also ReadApple retakes 2nd spot in global smartphone market Since the introduction of the Apple iOS policy, most users have opted out, leaving advertisers in the dark about how to target them. "Advertisers have responded by cutting back their spending at Snap, Facebook, Twitter and YouTube and diverted their budgets elsewhere: in particular to Android phone users and to Apple's own growing ad business," it added. Snap "fared the worst as a percentage of its business" because its advertising is mainly tied to smartphones. Facebook CEO Mark Zuckerberg has slammed Apple for its App Store policies, saying the iOS privacy changes are negatively affecting its business. In an earnings call after posting robust Q3 results late last month, Zuckerberg said that the company did experience revenue headwinds this quarter. "Apple's changes are not only negatively affecting our business, but millions of small businesses, and what is already a difficult time for them and the economy," he told the analysts. Facebook has been fiercely critical of the iOS 14 changes since these were introduced some months ago. Sheryl Sandberg, Facebook's Chief Operating Officer, said that the biggest impact to them has come from iOS 14 changes which advantaged Apple's own advertising business. "One is that the accuracy of our ads targeting decreased, which increased the cost of driving outcomes for our advertisers. And the other is that measuring those outcomes became more difficult," Sandberg said.