Google reaches $4 trillion market cap as AI momentum accelerates

Alphabet reached a $4 trillion market value on Monday, becoming the fourth U.S. company to cross the mark due to rising AI demand.

Shares of Alphabet rose 1% and closed at $331.86. The move pushed the company’s market capitalization just above $4 trillion.

The gain followed an announcement from Apple. Apple said it will use Google’s Gemini as the foundation for its artificial intelligence models and the next generation of Siri.

Gemini is Google’s flagship AI system. It is designed to understand text, images, and code, and to generate responses in plain language. Siri is Apple’s voice assistant, used on iPhones and other devices.

Alphabet now stands alongside Nvidia and Microsoft as companies that have reached the $4 trillion level. Apple also crossed that threshold in October, though Apple and Microsoft later slipped below it.

Alphabet ended 2025 as one of Wall Street’s strongest performers. Its stock climbed 65% during the year, marking its sharpest annual gain since 2009.

The rally followed progress in artificial intelligence and the resolution of major regulatory issues. In November, Google introduced Ironwood, its seventh-generation tensor processing unit. These chips are custom-built for AI workloads and are meant to reduce reliance on outside suppliers.

In December, Google released Gemini 3. Reviews highlighted improvements in speed and accuracy. Those features matter as companies race to build systems that can reason, write, and assist users across many tasks.

Competition remains intense. OpenAI continues to draw users with ChatGPT and Sora. ChatGPT answers questions and writes text, while Sora creates videos from written prompts.

Alphabet has eased concerns that AI chatbots could weaken online advertising. Investors have focused on Google’s scale, data, and infrastructure.