Shares of Alphabet fell as much as 4% as trading got underway in New York. If the losses hold throughout the day, it will notch the biggest drop since early February. Microsoft was up 1.7%.
Alphabet Inc. was headed for its biggest single-day decline in more than two months following a report that Samsung Electronics Co. has considered replacing Google with Microsoft’s Bing as the default search engine on its devices.
Google employees were shocked when they learned about Samsung’s threat in March, the New York Times reported on Sunday, citing internal messages. The contract between Alphabet and the world’s leading smartphone maker is under negotiation, and Samsung could still stick with Google, according to the Times.

