California voters face Proposition 40, a one-time 5% wealth tax on billionaires' net worth as of late 2026, alongside two well-funded countermeasures, Propositions 41 and 42, that would nullify it if either receives more votes. Governor Gavin Newsom has endorsed Prop 42, which bans new taxes on personal property and retroactive levies, while billionaire-backed groups have spent over $200 million on opposition efforts. Polling shows narrow or mixed support for the wealth tax, but historical patterns of California voters rejecting tax measures, combined with the direct conflict rules on the November 2026 ballot, have led traders to assign an 86.5% probability that the tax proposal will not prevail over the opposing propositions.