Tesla boss Elon Musk saw more than three-quarters of a billion dollars wiped off his fortune after a botched launch of his latest electric vehicle.
Shares in the firm slid following the bungled unveiling of the pickup truck, which had its supposedly unbreakable window glass shatter twice during a demonstration.
The failed stunt came after Mr Musk had bragged about the strength of the glass on the futuristic, stainless steel-skinned Cybertruck, brought on stage amid lasers and flames.
He told the audience in California: “You want a truck that’s really tough, not fake tough.
“You want a truck you can take a sledgehammer to, a truck that won’t scratch, doesn’t dent.”
To prove it he then directed a Tesla designer to strike the door with a sledgehammer, resulting in no damage.
But when they threw a metal ball at the driver’s side window and it splintered, Mr Musk said: “Oh my f****** God.”
“Maybe that was a little too hard,” he added.
The passenger window also cracked when the test was repeated.
Mr Musk said: “At least it didn’t go through. That’s a plus side.
“We’ll fix it in post.”
The failure overshadowed the truck’s launch, with some analysts also critical of its radical wedge-shaped design.
In response Tesla stocks fell by more than 6%, cutting Mr Musk’s net worth by $768m (£598m) in a single day, to $23.6bn (£18.4bn), according to Forbes magazine.
It ranks the 48-year-old entrepreneur as the 41st-richest person in the world.
While the pickup opens up a profitable new market to Tesla, it faces stiff competition from the dominant motor giant Ford.
The electric vehicle pioneer has also struggled to meet delivery targets for its existing cars, and some fear the Cybetruck will shift the company’s attention away from the aim of more consistently meeting its targets.
The electric pickup truck will be in production in 2021, Mr Musk said.
Cowen Investment Research analyst Jeffrey Osborne wrote in a note to investors: “Tesla’s Cybertruck reveal will likely disappoint current pickup truck owners, and we see the vehicle remaining a niche and not a mainstream product.”
He went on to add that “we do not see this vehicle in its current form being a success”.
Tesla is not the only company to have their slick launches end in embarrassment.
At Detroit’s motor show earlier this year, an Infiniti concept electric SUV failed to start and the company could not get it onto the stage.
One of the most infamous fiasco’s happened in Detroit in 2008 when Chrysler showed off the new pickup truck with a cattle drive outside the convention centre.
But some of the livestock started mating, distracting attention away from the vehicle.
Bud Liebler, who was marketing chief at Chrysler from 1980 until 2001, said: “You can rehearse it 100 times, and the 101st is the time you do it before the public and it fails.”