Elon Musk thought he had OpenAI cornered. The traders on Kalshi say no.
His odds of winning have fallen from 60% to 40%. That swing took less than two weeks.
A move that big needs a real cause. The cause was Musk taking the stand.
The trial opened April 27 in a federal court in Oakland. The next day, Kalshi traders gave Musk a 60% chance to win.
Then he took the stand for three days, ending April 30. By May 2, his odds had crashed to about 34%.
That was two days after his last hour on the stand. Eric Zitzewitz teaches economics at Dartmouth.
He told CNBC the market was reading the press coverage of the trial. The headlines were not kind to Musk.
On the stand, Musk said OpenAI's Sam Altman and Greg Brockman tried to "steal a charity." He said he came up with the idea, the name, and the early funds before being pushed out.
Things got hotter on cross. Musk clashed with the firm's lead lawyer, William Savitt, and said the questions were built to trick him.
Then a court filing dropped. It showed Musk had texted Brockman about a deal just days before the trial.
That detail gave traders a reason to doubt him. By Wednesday afternoon, the odds had nudged back up to 40%, but the price is still well below where it started.
The OpenAI suit isn't even the biggest Musk bet on Kalshi. There are more than 150 active Musk-related contracts on the site.
The largest is a $4.2 million market on when SpaceX will announce its IPO. Another $1.5 million contract tracks the 12th Starship launch.
The OpenAI contract sits behind both. It has $890,000 in total volume, with another $48,500 traded in the last day.
Why so much volume? Zitzewitz pointed to two reasons.
Traders flock to markets that are about to settle, and lots of activity tends to draw more activity. In short, the closer the verdict, the more money piles in.
Musk gave about $38 million to OpenAI before he left the board in 2019. The suit asks whether that cash was used in ways that broke the firm's nonprofit mission.
OpenAI is still a nonprofit. But it has a controlling stake in its for-profit arm.
Musk and Altman started OpenAI together in 2015. Musk says he provided the early money, the name, and the team that got the firm off the ground.
The fight a decade later is over what each side agreed to back then. It is also over what counts as a breach of that early deal.
The case is being closely watched in Silicon Valley. A win for Musk would likely shake up how OpenAI runs its for-profit arm.
A win for OpenAI would clear the firm to keep raising and spending at a record pace. The firm has called the case "baseless" on X.
The judge will decide whose story holds up. The price on Kalshi says traders aren't betting on Musk.
