A proposal in California to levy a 5% wealth tax on billionaires is facing strong opposition, with tech billionaires raising over $300 million to fight the tax. The proposal, which will be voted on November 3, would impose a one-time tax on California billionaires if passed.

California Governor Gavin Newsom also opposes the tax, calling it "poorly written" and arguing that it would harm the state's economy if billionaires (with an estimated combined wealth of $2.3 trillion) were to move out, as Meta founder Mark Zuckerberg reportedly plans to do.

The opposition's fundraising significantly outpaces that of supporters, who have raised only $32 million, making it one of the most expensive ballot measures in history.