For search engines, nothing is more lucrative than being the default provider of a popular web browser. In the past, companies have paid huge sums for the job. Yahoo gave Mozilla more than $ 300 million to be the default Firefox engine, but the company was later outbid by Google. A new report estimates that Google's place as the default iPhone search engine costs the company $ 9 billion this year.

The amount that Google provides Apple to be the default search engine on iOS is supposed to be a well-kept secret, but the details escape from time to time. As a result of Google's lawsuit with Oracle, the 2014 figure was $ 1 billion. The number was based on advertising revenue generated by iPhone searches, but it is unclear if this is still the case.

According to new estimates by analyst firm Goldman Sachs, Google could pay Apple up to $ 9 billion in 2018 and about $ 12 billion next year. "We believe these revenues are calculated based on the number of searches that Apple platform users have made with Siri or the Safari browser," said a Goldman representative.