Fisher Island, the exclusive private island off Miami Beach, lost this year for the first time in two years the title of the most expensive ZIP code in the United States, according to data from PropertyShark and Bloomberg reported by El Nuevo Herald.
The Californian enclave of Atherton (zip code 94027), located in the heart of Silicon Valley about 18 miles northwest of San José, reclaimed the top spot by recording an average home sale price of nearly 10 million dollars during the first half of 2026, an increase of approximately 20% compared to the previous year.
The driving force behind Atherton's rise is the boom in artificial intelligence: employees and founders of companies like OpenAI, Anthropic, and SpaceX are turning their gains into equity through purchases of luxury properties in this small town of just about 7,000 residents.
So far in 2026, Atherton has already recorded five home sales of at least 30 million dollars, approaching last year's record, according to Bloomberg.
The area is home to venture capitalist Marc Andreessen, WhatsApp co-founder Jan Koum, and Golden State Warriors star Stephen Curry.
Fisher Island, for its part, had climbed to the top position in the 2025 PropertyShark ranking with an average price of 9.5 million dollars, a jump of 65% compared to 2024, when it held the fourth place with 5.75 million.
That rise was driven by the mass migration of wealthy executives and investors from high-tax states during and after the pandemic, a movement that led billionaires like Ken Griffin, Jeff Bezos, and Carl Icahn to settle in Miami-Dade.
Losing the top spot does not diminish the island's appeal. The private island of 216 acres, accessible only by ferry, yacht, or helicopter, remains one of the most exclusive residential enclaves in the country, with condominiums regularly selling for tens of millions of dollars and some residences listed for up to 85 million.
The change in leadership illustrates how sources of extreme wealth in the country are evolving: while southern Florida was driven by hedge fund managers and private equity executives, Silicon Valley is now generating a new generation of ultra-wealthy buyers thanks to the tech boom.
The south of Florida, however, continues to dominate in the ultra-luxury segment. According to Bloomberg, seven of the 11 residential sales exceeding 100 million dollars recorded in the U.S. last year took place in Florida, and the cost of living in Miami surpassed that of New York for the first time in July 2026.
The Miami-Dade real estate market showed signs of slowing down in 2026, with the value of new construction falling from $8.6 billion to $5.1 billion compared to 2025, which could partly explain Fisher Island's drop from the top position in the annual PropertyShark ranking.
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