Sergey Brin has poured $102 million into Building a Better California, turning the Google cofounder into the state’s most consequential political financier this cycle. The vehicle has raised hundreds of millions from tech executives and venture capitalists, deploying more than $304 million through Oct. 20 on a slate of ballot measures that reaches well beyond the wealth-tax fight that sparked the mobilization.
The counter-measure strategy
Proposition 40 would impose a one-time 5% levy on assets above $1 billion held by California residents as of Jan. 1, 2026, with the Legislative Analyst’s Office projecting tens of billions in collections over several years. Building a Better California has directed roughly $118.5 million to defeat it. The group has spent another $186 million backing Propositions 41 and 42, companion measures designed to neutralize the tax even if voters approve it. Proposition 41 would prevent new taxes from escaping the state spending cap and mandate audits of programs funded by special levies. Proposition 42 would ban retroactive taxation outright. The Legislative Analyst’s Office says that if either alternative draws more “yes” votes than Proposition 40, the wealth tax could be blocked despite a majority voting for it.
Billionaire money floods the zone
A Politico analysis found more than 70 current and former California billionaires steering a record $612 million into state races this cycle. Nearly half that sum targets the wealth-tax fight, with at least 30 ultrawealthy donors contributing over $293 million specifically to defeat Proposition 40. For Brin, whose fortune Bloomberg estimates at $231 billion, the potential liability is personal. In an April interview with The New York Times he likened the proposal to the kind of asset seizure seen in authoritarian regimes.
The union behind the tax
The measure was placed on the ballot by Service Employees International Union-United Healthcare Workers West, which argues the revenue is needed to shield California’s healthcare system from federal funding cuts. Ninety percent of proceeds would go to healthcare, the remainder to education and food assistance. Progressive leaders including Sen. Bernie Sanders and Rep. Ro Khanna have endorsed the measure.
Infrastructure built to last
Building a Better California’s platform also endorses Propositions 1, 3, 37, 41 and 42. The group put $10 million behind Proposition 45, which would revise the state’s environmental review process, and $6 million behind Proposition 37, a $25 billion homebuyer loan fund. The breadth of spending signals an operation designed to shape California policy long after the Nov. 3 vote on Proposition 40 is settled.