This is a column about AI. My fiancé works at Anthropic. See my full ethics disclosure here .

On Thursday afternoon, Demis Hassabis celebrated a milestone for Google’s AI efforts: Gemini 4 Carbon, a new large language model that is currently available only to cyber defenders, topped Artificial Analysis’ Intelligence Index. After a series of delays in new model releases and a growing perception that the company is falling off the frontier, early signs suggest that Carbon marks a return to form. For Alphabet’s chief scientist, the news surely felt like a vindication.

Investors, however, are much less certain. On the same day, Google’s parent company had its worst day in history as a public company. Alphabet’s stock fell 12.6 percent, erasing around $500 billion in market value. The loss marked the second-biggest stock market plunge ever, following Nvidia’s $593 billion slide in January 2025.…