Shares of Google parent Alphabet (GOOGL) plunged Wednesday after an Apple (AAPL) executive reportedly said the iPhone maker is looking to add AI-powered search options to its Safari browser, and suggested they could eventually replace standard search engines like Google’s.

Shares of Alphabet were down 9% in recent trading. They’ve lost about a fifth of their value since the start of the year. 

Apple’s senior vice president of services, Eddy Cue, said Wednesday during testimony in the U.S. Department of Justice’s lawsuit against Alphabet that searches on Apple’s Safari fell last month for the first time, and attributed the drop to rising AI use, Bloomberg reported. 

Cue said Apple has had discussions with Perplexity AI, as it looks to add AI search options to its Safari browser, with expectations their use could overtake standard search engines like Google’s, the report said. Apple has reportedly held talks with Anthropic and ChatGPT maker OpenAI as well.

Such a shift could also hit Apple’s revenue—something Cue said he’s “lost a lot of sleep thinking about.” Google pays an estimated $20 billion a year to make its search engine the default option on Safari, and Apple makes a cut of Google’s ad revenue from searches through the browser. Shares of Apple slid about 2% in recent trading.

This article has been updated since it was first published to include additional information and reflect more recent share price values.