A six-bedroom, nine-bath mansion in Atherton, featuring a theater, a private rose garden and a spa, hit the market earlier this year for nearly $32 million and found a buyer within 72 hours, more than half a million dollars above asking. The town of roughly 7,000 residents has already recorded five property sales of at least $30 million this year, compared with a record of six in all of 2025, according to Tom LeMieux, a broker associate with Compass. The median home price has surged 20% to almost $10 million in the first half of 2026 compared to the same period last year, PropertyShark data show. With the boom, Atherton has regained the title of the most expensive US ZIP code, surpassing Miami’s Fisher Island. Ken DeLeon, a luxury realtor for more than two decades, estimates that more than 50 homes will sell for at least $10 million this year, comparing the boom to the “frenzied feel” of the 2000 dot-com era. The demand reflects the Bay Area’s K-shaped economy as the AI industry expands, creating fortunes for founders and investors while worsening affordability challenges. California voters will decide on a ballot measure in November that would levy a one-time 5% tax on billionaires to help pay for healthcare. Dana Carmel, a luxury real estate agent, said many ultra-high-net-worth individuals have deep business, family,