Google pays Apple 36% of all ad revenue it generates when a user uses Apple’s Safari browser. The figure, which is supposed to remain confidential, was revealed by Kevin Murphy, an economics professor at the University of Chicago, during his testimony in court defending Alphabet, Yahoo reported.

The figure shed more light on the relationship between two of the world’s largest technology companies, which have come under antitrust scrutiny in the past few years.

The Justice Department accuses Google of using its vast resources to maintain market dominance by paying companies like Apple, whose iPhone, iPad and Mac devices have billions of users combined, to be the default search engine on Safari. In 2021, Google allegedly paid Apple “about $18 billion” to be the default search engine in Safari, a New York Times report reveals.

Last week, Google and Apple had raised objections making details of their arrangement public, Bloomberg noted. Google said that making more details public “would unreasonably undermine Google’s competitive standing in relation to both competitors and other counterparties” in a court filing.

It’s not clear how much ad revenue Google generates from Safari, but it’s safe to assume that 36 percent of that number would likely be tens of billions of dollars. In 2022, Google’s total revenue was $279.8 billion, and a majority of it came from advertising.