[California's 5% Billionaire Wealth Tax Sparks Fierce Battle, Opposition Raises $318 Million] Golden Finance reports that on October 13, a political group backed by some of the world's wealthiest individuals is pouring massive funds into the final stages to block California's proposed wealth tax, further intensifying one of the most expensive political battles of this U.S. election cycle. The political lobbying organization Building a Better California, funded by Google co-founder Sergey Brin and other billionaires, has raised approximately $318 million since its establishment earlier this year, including $21 million in donations disclosed on Saturday. Most of the funds are being used to oppose Proposition 40, which proposes a one-time 5% wealth tax on California billionaires. A source familiar with the matter revealed that the organization expects total fundraising to reach approximately $350 million by election day. The massive political spending is escalating the controversy further. The wealth tax proposal has not only caused divisions within California's Democratic Party but has also prompted billionaires to contribute significant political donations, making it a critical test of whether voters support taxing immense wealth. With less than a month until election day, polls show both sides are neck and neck. Opponents are leveraging their overwhelming financial advantage to launch extensive advertising campaigns on television and digital platforms attacking the proposal.