Sergey Brin, co-founder of Google, has climbed to the position of the world's third-richest person, with his net worth reaching an estimated $255.6 billion, according to Forbes' Real-Time Billionaires List on January 13, 2026. This significant rise places him ahead of Amazon founder Jeff Bezos ($253.2 billion) and Oracle's Larry Ellison ($251.3 billion). Brin's ascent in the global wealth rankings trails only fellow Google co-founder Larry Page ($277 billion) and Tesla's Elon Musk ($725.3 billion). This personal wealth milestone for Brin coincides with Alphabet, Google's parent company, achieving a historic $4 trillion market capitalization. This landmark valuation, which occurred around January 12-13, 2026, was primarily propelled by renewed investor optimism surrounding Alphabet's robust advancements in artificial intelligence. A pivotal factor in this surge was the announcement of a multi-year AI partnership with Apple, wherein Apple will integrate Google's Gemini for its AI models and the next generation of Siri. This strategic collaboration underscores Google's leading position in the burgeoning AI landscape. Alphabet now joins an exclusive club of companies, including Nvidia, Microsoft, and Apple (though the latter two have occasionally fluctuated below this threshold), to reach the $4 trillion valuation. The company's stock rallied over 65% in 2025, marking its strongest performance since 2009, with continued gains in early 2026. This news highlights the profound impact of AI innovations on the valuations of global technology giants and the dynamic shifts in the wealth of their founders.