Shares of Alphabet ( GOOGL -1.02%) ( GOOG -0.92%) sank after Apple executive Eddy Cue said that searches on Safari declined for the first time ever in April. Cue attributed the decline to people using more artificial intelligence (AI) chatbots and predicted that AI search engines will eventually replace traditional search.

The long-simmering question of whether artificial intelligence could truly disrupt Google’s search dominance ignited investor fears on Wednesday, sending Alphabet Inc.’s stock tumbling after a high-ranking Apple executive testified that AI usage is already cutting into traditional search activity on iPhones.

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