Analysts for the financial services giant Goldman Sachs have estimated that Google paid Apple around US$9.5 billion over the calendar year 2018 to remain the default search engine on iOS-powered devices. Bankers are concerned that Apple, especially its Services division, is relying too heavily on this particular revenue source.
https://www.notebookcheck.net/Analysts-estimate-Google-paid-Apple-US-9-5-billion-in-2018-for-default-search-engine-status.406986.0.html