Alphabet co-founder Sergey Brin donated more than $1.1 billion worth of the company's stock this week. The majority of the donation, approximately $1 billion from over 3.5 million shares, is designated for Catalyst4, a nonprofit organization Brin established in 2021 to fund research into central nervous system disorders and solutions for climate change. Additional funds were directed to his family foundation, which will receive about $90 million, and the Michael J. Fox Foundation for Parkinson's research, which was allocated $45 million. This philanthropic act follows a significant increase in Brin's personal wealth, which has grown by over $97 billion in 2025, largely due to the rally in Alphabet's stock fueled by its advancements in artificial intelligence.