A new estimate suggests that Google will end up paying in excess of $9 billion to stay the default search tool in Apple's Safari browser this year, and possibly far more in 2019.
The figure could potentially grow to $12 billion next year, according to analyst Rod Hall, cited by Business Insider. In 2017 Google is thought to have paid over $3 billion.
Access to Safari on iPhones and iPads is critical to Google, which generates most of its money from advertising. Safari does support Bing, Yahoo, or DuckDuckGo for search, but most people are likely to stick with the default option as long as it's functional.
For Apple, Google's dependence has been a boon to its services segment. The company has previously told the U.S. Securities and Exchange Commission that licensing fees like Google's are the main driver of the segment's growth, even with the popularity of Apple Music.
Another factor holding Google in place may be the potential backlash from ditching Google. While much of the engine's popularity stems from being a default, alternatives like Microsoft's Bing -- used in Siri searches -- have been criticized for sub-par results.