FILE – A woman walks by a giant screen with a logo at an event at the Paris Google Lab on the sidelines of the AI Action Summit in Paris, Sunday, Feb. 9, 2025. (AP Photo/Thibault Camus, File)

OpenAI‘s announcement of ChatGPT Atlas, an AI-powered web browser, triggered a dramatic $150 billion plunge in Alphabet’s market value on Tuesday, marking one of the most significant single-day market reactions to a tech product launch this year. The reveal came through a cryptic six-second video posted on X showing browser tabs, followed by a livestream where CEO Sam Altman declared the browser represents “a rare once-a-decade opportunity to rethink what a browser can be about.”Alphabet shares initially fell as much as 4.8% to $246.15 within hours of OpenAI’s announcement, though they recovered somewhat to close down 2.4% at $250.46.

OpenAI bets big on browser dominance

OpenAI CEO Sam Altman positioned Atlas as a revolutionary reimagining of web browsing, not just another Chrome competitor. Although, it happens to be built on the same underlying technology as Google Chrome–the Chromium. Available now on macOS with mobile and Windows versions coming soon, Atlas embeds ChatGPT directly into every webpage, eliminating the need to switch tabs or copy-paste queries.The browser’s signature feature is “agent mode,” where AI takes control of your cursor and keyboard to complete complex tasks—booking flights, researching products, even editing documents—while you watch or walk away. Only Plus and Pro subscribers get access to this functionality initially, though free users can still use the basic browser.“We think AI represents a rare once-a-decade opportunity to rethink what a browser can be,” Altman declared during Tuesday’s livestream, flanked by engineers who previously built Chrome and Firefox.

Google Chrome‘s monopoly faces its biggest test

The stakes extend far beyond browser market share. Google derives most revenue from search advertising, and AI answer engines threaten that entire business model by delivering direct responses instead of ad-laden results pages. With 800 million weekly ChatGPT users, OpenAI has a massive built-in audience ready to switch.Google isn’t standing still—it recently integrated Gemini AI throughout Chrome and narrowly avoided a court-ordered breakup of the browser last month. As third-quarter earnings approach October 29, investors will scrutinize whether AI competition is already denting Google’s search dominance.