A landmark Apple partnership accelerates Alphabet’s AI ambitions and market valuation. The tech giant joins an exclusive financial echelon dominated by only a handful of companies. This milestone caps a historic year of record-breaking performance for Alphabet’s stock.

Alphabet, the parent company of Google, has officially eclipsed a $4 trillion market capitalization, cementing its place among the world’s most valuable public companies. This surge was propelled by the announcement that Apple selected Google’s Gemini AI engine to power a new generation of its Siri intelligence and other artificial intelligence features. The strategic partnership signals a major consolidation in the AI arms race and immediately resonated with investors, sending Alphabet shares higher.

With this achievement, Alphabet enters the rarefied $4 trillion club alongside peers Nvidia and Microsoft, which first reached the milestone in July, and Apple, which first hit it in October. The market cap frontier has proven volatile, however, with both Apple and Microsoft fluctuating below the $4 trillion line in subsequent months. Alphabet’s ascent underscores the intense investor focus and premium being placed on leading artificial intelligence infrastructure and strategic alliances.

The record valuation culminates an extraordinary run for Alphabet on Wall Street. The company ended 2025 as one of the top market performers, with its stock skyrocketing 65% over the year. This represents the most aggressive annual rally for the company since 2009, when shares rebounded powerfully in the wake of the financial crisis. The dramatic growth highlights a pivotal year where Alphabet’s AI investments and core business strength converged to drive unprecedented shareholder value.