The company which became well known for its idea of shooting people hundreds of miles an hour through a vacuum has shut down.
The aim of Hyperloop One, based on an idea by Elon Musk, was to dramatically cut journey times.
It has previously received backing from Virgin founder Richard Branson, but he pulled out last year.
The firm will lay off its remaining staff by the end of the year, according to Bloomberg.
The company had promised a new era of high speed travel, using magnetic levitation (maglev) technology – which is already used in some transport systems – within a vacuum tube.
This would reduce friction and air resistance, allowing the train to travel at speeds of 700mph (1,127km/h).
It was also meant to be greener than current high-speed transport.
However, while Hyperloop One did build some prototypes in the Nevada desert, the project stalled with some experts expressing doubts about its engineering challenges.
It would have required the construction of giant tubes across the countryside and within towns.
It also had a problem with corners – so all the tubes would have to be in a straight line.
A trial of the system took place with two company employees in 2020 – the first successful passenger ride using hyperloop technology.