California billionaire tax odds crash as Newsom fights ballot bid

Chances that a proposed billionaire tax will appear on California's ballot dropped from 88% to 35.5% over the past week on prediction platform Kalshi.

The move follows reports from Politico and Bloomberg News that Governor Gavin Newsom is pushing to block the measure before a June 25 deadline. The proposal, backed by the Service Employees International Union – United Healthcare Workers West, calls for a one-time 5% tax on a billionaire's net worth.

The union argues the tax would shore up the state's healthcare system after federal funding cuts. "The tax would be paid only by Californians worth more than $1 billion – which is about 200 people who hold a combined wealth of $2 trillion," the union's website states. It added that it submitted more than 1.5 million signatures from California voters. Only 875,000 are required to qualify for the ballot.

Newsom's reported opposition comes as he seriously considers a presidential run. On Monday he accused President Donald Trump of ordering the Department of Justice to investigate him and his wife. In a post on X, Newsom said Trump was targeting him because "I am considering running for President."

The odds on Kalshi reflect changing views on the measure's path to the ballot. The deadline remains June 25.

Disclosure: CNBC and Kalshi have a commercial relationship that includes customer acquisition and a minority investment.