Updated Oxfam analysis finds the 10 wealthiest Californians are now worth a collective $1.199 trillion, up $244.1 billion from September 2025.
As Californians prepare to vote on Proposition 40, which could authorize a one-time, 5% wealth tax on the state’s billionaires, Oxfam released an updated analysis today detailing how California’s unchecked billionaire wealth has continued to explode far beyond global averages. The 10 richest California billionaires saw their wealth increase by over 25% — $244.1 billion — between September 2025 and September 2026, more than double the rate of global billionaire wealth, which grew by 12.2% over the same period.
This new data, which comes alongside Oxfam America’s endorsement of the California Billionaire Tax Act (Prop. 40), highlights the urgent need for action to curb runaway inequality and outsized billionaire power in the state:
- As of September 30, 2026, the 10 wealthiest California billionaires are worth $1.199 trillion according to Forbes data.
- The average wealth growth of the 10 richest California billionaires is equivalent to an hourly wage of $11.7 million.
- It would take a typical California worker 419,102 years to earn as much as one of the 10 richest California billionaires did, on average, over the past year ($24.4 billion).
“As the home to more billionaires than any other state, California is ground zero for our current gilded age. These extraordinary levels of wealth concentration necessitate equally extraordinary solutions, and the California Billionaire Tax Act is a long-overdue response to the inequality crisis we’re all facing,” said Rebecca Riddell, associate director of economic justice at Oxfam America.
While California provides an extreme example of today’s rampant inequality, the picture is also stark at the national level. The richest 0.1% in the U.S. now hold the highest share of wealth on record — 15% — since the Federal Reserve started tracking in 1989, and the top 1% now own more wealth than the bottom 90% of the country combined. President Trump’s One Big Beautiful Bill Act (OBBBA) is further exacerbating these divides, providing $60.3 billion in tax giveaways to the top 0.1% in 2027 alone.
Meanwhile, ordinary people across the country are struggling with affordability, and recent federal cuts in the OBBBA will only increase the cost of essentials like food and healthcare. In California alone, over one million people could lose their healthcare coverage under Medicaid as a result of OBBBA cuts, and over 3 million households could face reductions in food assistance.
Oxfam America has endorsed the California Billionaire Tax Act proposal and encourages California voters to vote yes on the ballot initiative, which would help keep local hospitals and emergency rooms open, fund food aid, and support public education through a one-time, 5% tax on the state’s roughly 250 billionaires.
Oxfam is a global organization that fights inequality to end poverty and injustice. We offer lifesaving support in times of crisis and advocate for economic justice, gender equality, and climate action. We demand equal rights and equal treatment so that everyone can thrive, not just survive. The future is equal. Join us at oxfamamerica.org.
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Notes to editors:
Download Oxfam America’s April 2026 analysis of California billionaire wealth.
Data on individual wealth of California billionaires comes from Forbes Media, LLC. Figures compare wealth on September 30, 2025 with wealth on September 30, 2026. Data on residence of California billionaires comes from Forbes Media, LLC as of September 30, 2026. The California Billionaire Tax Act would impose a wealth tax on all billionaires who resided in California as of January 1, 2026.
The “typical California worker” is a worker with median earnings in the state, using most recent data from the Bureau of Labor Statistics’ Occupational Employment and Wage Statistics (May 2025). Across all occupations, the median California worker earned $58,240 in 2025.
The equivalent hourly wage for California’s 10 richest billionaires was calculated assuming individuals work 40 hours per week, 52 weeks per year.